Contents 1
Introduction ...................................................................................................................................................................13 1.1
The Track .................................................................................................................................................................13
1.2 The Sub-Structure.....................................................................................................................................................13 1.2.1 Ballasted vs. Non-Ballasted (Slab) Track..............................................................................................................15 1.3 Sleepers (Ties) ...........................................................................................................................................................17 1.3.1 Wooden sleepers ................................................................................................................................................17 1.3.2 Concrete Sleepers...............................................................................................................................................18 1.3.3 Plastic sleepers...................................................................................................................................................19 1.3.4 Twin-Block Sleepers ..........................................................................................................................................19 1.3.5 Other sleeper variants .........................................................................................................................................20 2
Design............................................................................................................................................................................20 2.1 Track Alignment .......................................................................................................................................................20 2.1.1 Curves...............................................................................................................................................................24 2.1.1.1 Track Transition Curve ..............................................................................................................................24 2.1.1.2 Cant .........................................................................................................................................................25 2.1.1.3 Side Wear .................................................................................................................................................30 2.1.1.4 Twist ........................................................................................................................................................30 2.1.1.5 Warp ........................................................................................................................................................30 2.2
Structure Gauge and Kinematic Envelope .................................................................................................................31
2.3
Monuments and Datum Plates...................................................................................................................................31
2.4
U.S. track classes .......................................................................................................................................................31
2.5 Route Selection..........................................................................................................................................................31 2.5.1 Route Optimising Criteria ...................................................................................................................................31 2.5.2 System Design as a Function of Train Performance, Train Resistance.....................................................................32 2.5.2.1 Choosing best route for a freight line...........................................................................................................32 2.5.2.2 Grade Resistance .......................................................................................................................................36 2.5.2.3 Curve Resistance: ......................................................................................................................................36 2.5.2.4 Choosing the Preferred Route .....................................................................................................................38 2.6 Tools .........................................................................................................................................................................39 2.6.1 Bentley Rail Track .............................................................................................................................................39 2.6.1.1 Track Design Solutions for Railways...........................................................................................................40 2.6.1.2 Existing Track Analysis .............................................................................................................................43 2.6.1.3 Regression Analysis...................................................................................................................................44 2.6.1.4 Horizontal Alignment Design .....................................................................................................................44 2.6.1.5 Turnouts ...................................................................................................................................................45 2.6.1.6 Switches and Crossings ..............................................................................................................................46 2.6.1.7 Vertical Design .........................................................................................................................................47 2.6.2 Novapoint Railway.............................................................................................................................................48 2.6.2.1 Creating the Geometry ...............................................................................................................................48 2.6.2.2 Modelling the project .................................................................................................................................49 2.6.2.3 Analysing the project .................................................................................................................................50 2.6.2.4 Presenting the project.................................................................................................................................50 2.6.2.5 Visualising the project ...............................................................................................................................50 3
4
Rail Profile.....................................................................................................................................................................51 3.1
History ......................................................................................................................................................................51
3.2
Tramway track .........................................................................................................................................................51
3.3
Bullhead Rail ............................................................................................................................................................54
3.4
Flanged T-Rail ..........................................................................................................................................................55
3.5
Vignoles Rail .............................................................................................................................................................55
Construction...................................................................................................................................................................57 4.1
Fastening rails to sleepers/ties....................................................................................................................................57
4.2
Joining the Rails........................................................................................................................................................58
Page 1 of 259
4.2.1 Jointed track ......................................................................................................................................................59 4.2.1.1 Rail Movement Joints ................................................................................................................................60 4.2.2 Insulated joints...................................................................................................................................................62 4.2.2.1 Continuous insulated joints.........................................................................................................................63 4.2.2.2 Non-Continuous insulated joints .................................................................................................................63 4.2.2.3 Bonded insulated joints ..............................................................................................................................63 4.2.3 Continuous Welded Rail (CWR) Track ................................................................................................................64 5
Railway Track Layouts ...................................................................................................................................................65 5.1 Railroad Switch/Point/Turnout .................................................................................................................................65 5.1.1 History..............................................................................................................................................................65 5.1.2 Overview ..........................................................................................................................................................65 5.1.3 Turnout Components .......................................................................................................................................81 5.1.3.1 Basic Parts ................................................................................................................................................81 5.1.3.2 Points (point blades) ..................................................................................................................................82 5.1.3.3 Frog (Common Crossing) ...........................................................................................................................83 5.1.3.4 Guard Rail (Check Rail).............................................................................................................................89 5.1.3.5 Joints........................................................................................................................................................92 5.1.3.6 Throwing a Switch - Switch Stands and Targets ...........................................................................................93 5.1.3.7 Switch Motor / Point Machine ..................................................................................................................110 5.1.4 Operation .......................................................................................................................................................119 5.1.4.1 Facing and Trailing..................................................................................................................................119 5.1.4.2 Operation in cold conditions .....................................................................................................................125 5.1.5 Types of Turnouts..........................................................................................................................................129 5.1.5.1 Overview ................................................................................................................................................129 5.1.5.2 Simple Turnout .......................................................................................................................................129 5.1.5.3 Standard and Special Turnouts..................................................................................................................129 5.1.5.4 Crossovers ..............................................................................................................................................132 5.1.5.5 Double slip .............................................................................................................................................138 5.1.5.6 Single slip ...............................................................................................................................................144 5.1.5.7 Outside slip .............................................................................................................................................145 5.1.5.8 Stub switch .............................................................................................................................................146 5.1.5.9 Plate switch.............................................................................................................................................147 5.1.5.10 Three-way switch ....................................................................................................................................147 5.1.5.11 Interlaced turnout ....................................................................................................................................149 5.1.5.12 Gantlet (Gauntlet) Track ..........................................................................................................................149 5.1.5.13 Wye switch .............................................................................................................................................152 5.1.5.14 Run-off points .........................................................................................................................................153 5.1.5.15 Trap points..............................................................................................................................................153 5.1.5.16 Types of trap points .................................................................................................................................155 5.1.5.17 Catch points ............................................................................................................................................157 5.1.5.18 Track Circuit Interrupter ..........................................................................................................................159 5.1.5.19 Sand drag................................................................................................................................................161 5.1.5.20 Arrestor bed ............................................................................................................................................162 5.1.5.21 Derailers .................................................................................................................................................162 5.1.5.22 Dual gauge switches ................................................................................................................................163 5.1.6 Turnout System Solutions..............................................................................................................................164 5.1.6.1 High Speed Turnouts ...............................................................................................................................164 5.1.6.2 Metro and Tram Turnouts.........................................................................................................................164 5.1.6.3 Roller coaster switches.............................................................................................................................165 5.1.6.4 Heavy Haul Turnouts ...............................................................................................................................165 5.1.7 Classification of Switches ..............................................................................................................................170 5.1.8 Layout of Switches.........................................................................................................................................170 5.1.9 Safety Aspect of Switches .............................................................................................................................172 5.1.10 Using Turnouts ..........................................................................................................................................172 5.1.11 Sabotage: The sad story of malicious tampering on America's railroads .................................................173 5.1.12 Mechanical Interlocking in a Freight Yard .................................................................................................175 5.1.13 Accidents ...................................................................................................................................................181 5.1.13.1 Grayrigg Crash - Train crash points not inspected.......................................................................................181 5.1.13.2 Potters Bar crash - Several Potters Bar points 'were faulty' ..........................................................................183 5.1.13.3 Derailment of train EC 107 (Prague-Warsaw) ............................................................................................184 5.1.13.4 Abergele train disaster..............................................................................................................................185 5.2 Junctions.................................................................................................................................................................187 5.2.1 What is! ..........................................................................................................................................................188
Page 2 of 259
5.2.1.1 Measures to improve junction capacity ......................................................................................................188 5.2.2 Flying Junction ...............................................................................................................................................188 5.2.3 Level Junction ................................................................................................................................................189 5.2.3.1 Examples ................................................................................................................................................196 5.2.3.2 Drawbridge crossing ................................................................................................................................196 5.2.4 Double junction ..............................................................................................................................................196 5.2.4.1 Diamond.................................................................................................................................................197 5.2.4.2 Switched diamond ...................................................................................................................................197 5.2.4.3 Ladder ....................................................................................................................................................198 5.2.4.4 Single lead ..............................................................................................................................................198 5.2.4.5 Diamond and wide centres........................................................................................................................198 5.2.4.6 Flyovers..................................................................................................................................................199 5.2.5 Grand Union ..................................................................................................................................................199 5.3 Running Lines .........................................................................................................................................................200 5.3.1 Mainline or Main line......................................................................................................................................200 5.3.2 Branch line .....................................................................................................................................................200 5.3.3 Single Track...................................................................................................................................................200 5.3.4 Double Track .................................................................................................................................................201 5.3.4.1 Overview ................................................................................................................................................201 5.3.4.2 Operation................................................................................................................................................201 5.3.4.3 Construction............................................................................................................................................202 5.3.4.4 Oddities ..................................................................................................................................................203 5.4 Rail Siding ..............................................................................................................................................................204 5.4.1 Crossing Loop / Passing Siding or Loop .......................................................................................................204 5.4.1.1 System of working...................................................................................................................................205 5.4.2 Balloon Loop ..................................................................................................................................................207 5.4.2.1 Use.........................................................................................................................................................207 5.4.2.2 Examples ................................................................................................................................................207 5.4.2.3 History ...................................................................................................................................................209 5.4.2.4 Disadvantages .........................................................................................................................................209 5.4.2.5 Advantages .............................................................................................................................................209 5.4.2.6 Other Olympic stations ............................................................................................................................209 5.4.3 Headshunt (Escape Track) ............................................................................................................................209 5.4.3.1 Terminal Headshunts ...............................................................................................................................209 5.4.3.2 Shunting neck .........................................................................................................................................210 5.4.3.3 Run-round...............................................................................................................................................210 5.5 Yards ......................................................................................................................................................................210 5.5.1 Marshalling Yard (Classification Yard) ..........................................................................................................214 5.5.1.1 Flat-shunted yards ...................................................................................................................................214 5.5.1.2 Hump yards ............................................................................................................................................214 5.5.1.3 Gravity yards ..........................................................................................................................................216 5.6 Stations ...................................................................................................................................................................216 5.6.1 Station Design ...............................................................................................................................................216 5.6.2 Platform..........................................................................................................................................................216 5.6.3 Side platform..................................................................................................................................................216 5.6.3.1 Elevated Station with Side Platforms.........................................................................................................217 5.6.3.2 Elevated Station with Ticket Hall Below Platforms ....................................................................................218 5.6.4 Island (Centre) Platform.................................................................................................................................218 5.6.4.1 Advantages and tradeoffs .........................................................................................................................220 5.6.5 Bay platform...................................................................................................................................................220 5.6.5.1 Overview ................................................................................................................................................220 5.6.5.2 Dock platforms........................................................................................................................................220 5.6.6 Terminal Station Platform ..............................................................................................................................221 5.6.7 Spanish Solution (Barcelona Solution) ..........................................................................................................221 5.6.8 Cross-platform interchange ...........................................................................................................................222 5.6.8.1 Examples ................................................................................................................................................222 5.6.9 Platform Screen Doors ..................................................................................................................................223 5.6.10 Passenger Information Displays ...............................................................................................................224 5.7 Hill Climbing ..........................................................................................................................................................225 5.7.1 Horseshoe curve............................................................................................................................................225 5.7.1.1 Examples of horseshoe curves ..................................................................................................................225 5.7.2 Zigzags (Switchbacks)...................................................................................................................................225
Page 3 of 259
5.7.2.1 Advantages .............................................................................................................................................225 5.7.2.2 Disadvantages .........................................................................................................................................225 5.7.2.3 Locations of zigzags ................................................................................................................................226 5.7.3 Spiral..............................................................................................................................................................227 5.7.3.1 Calculations ............................................................................................................................................228 5.7.3.2 Examples of Spirals .................................................................................................................................228 5.8 Buffer Stop..............................................................................................................................................................229 5.8.1 What is! ..........................................................................................................................................................229 5.8.2 Energy-absorbing buffer stops ......................................................................................................................232 5.8.3 Warning lights ................................................................................................................................................233 5.8.4 Accidents .......................................................................................................................................................234 5.9 Level Crossing.........................................................................................................................................................235 5.9.1 What is! ..........................................................................................................................................................235 5.9.1.1 Safety .....................................................................................................................................................236 5.9.1.2 Crossings around the world ......................................................................................................................237 5.9.1.3 Crossbuck ...............................................................................................................................................241 5.9.1.4 International variants ...............................................................................................................................241 5.9.1.5 Multiple Tracks .......................................................................................................................................241 6
Rail Gauge ...................................................................................................................................................................242 6.1 Standard gauge .......................................................................................................................................................242 6.1.1 Origin .............................................................................................................................................................243 6.1.2 Ideal gauge ....................................................................................................................................................243 6.1.3 Piggyback operation ......................................................................................................................................244 6.1.4 Break of gauge ..............................................................................................................................................244 6.2 Broad gauge ............................................................................................................................................................244 6.2.1 Details ............................................................................................................................................................244 6.2.2 Broader gauges .............................................................................................................................................245 6.3 Scotch gauge ...........................................................................................................................................................247 6.3.1 End of Scotch gauge .....................................................................................................................................247 6.4 Narrow gauge..........................................................................................................................................................247 6.4.1 Overview ........................................................................................................................................................248 6.4.2 History of narrow gauge railways ..................................................................................................................248 6.4.3 Advantages of narrow gauge.........................................................................................................................248 6.4.4 Disadvantages of narrow gauge....................................................................................................................248 6.4.5 Exceptions to the rule ....................................................................................................................................249 6.4.6 Gauges used .................................................................................................................................................249 6.4.6.1 Medium gauge railways ...........................................................................................................................249 6.4.6.2 Two-foot gauge railways ..........................................................................................................................249 6.4.6.3 Minimum gauge railways .........................................................................................................................249 6.5 Dual gauge ..............................................................................................................................................................251 6.5.1 Configuration .................................................................................................................................................251 6.5.2 Gauge Conversion.........................................................................................................................................251 6.5.3 Cost of an example........................................................................................................................................252 6.5.4 Examples .......................................................................................................................................................252 6.5.5 Triple gauge ...................................................................................................................................................253 6.5.6 Accidents on dual-gauge railways .................................................................................................................253 6.5.7 Complexity of dual-gauge switches ...............................................................................................................253 6.5.7.1 Paradox ..................................................................................................................................................254 6.5.7.2 Gauge splitters ........................................................................................................................................254 6.5.8 Separate gauge .............................................................................................................................................254 6.5.9 Overlapping gauges.......................................................................................................................................254 6.5.10 Other methods of handling multiple gauges..............................................................................................254 6.5.11 Dual gauge dual voltage............................................................................................................................254 6.6
Variable (adjustable) gauge axles ............................................................................................................................256
6.7 Break-of-Gauge.......................................................................................................................................................256 6.7.1 Inconvenience................................................................................................................................................256 6.7.2 Overcoming a break of gauge .......................................................................................................................257 6.7.3 Major breaks of gauge ...................................................................................................................................257 6.7.4 Minor breaks of gauge ...................................................................................................................................258
Page 4 of 259
6.7.5
Other issues...................................................................................................................................................258
6.8 Future .....................................................................................................................................................................259 6.8.1 High speed.....................................................................................................................................................259 6.8.2 Mining ............................................................................................................................................................259 6.8.3 Kenya-Uganda-Sudan proposal ....................................................................................................................259 6.9 6.10
Rail sizes .................................................................................................................................................................259 Track maintenance .............................................................................................................................................259
Page 5 of 259
Table of Figures Figure 1: Rail Track Components................................................................................................................................................................. 13 Figure 2: The Sub-Structure......................................................................................................................................................................... 14 Figure 3: The main parts of an electrified double-track line. ............................................................................................................................ 14 Figure 4: Cuttings....................................................................................................................................................................................... 15 Figure 5: Embankments .............................................................................................................................................................................. 15 Figure 6: Slab Track System ........................................................................................................................................................................ 17 Figure 7: Wooden Sleepers.......................................................................................................................................................................... 18 Figure 8: Concrete Sleepers ......................................................................................................................................................................... 18 Figure 9: Twin Block Sleepers ..................................................................................................................................................................... 19 Figure 10: Mixed concrete and wooden sleepers ............................................................................................................................................ 19 Figure 11: Steel Sleepers ............................................................................................................................................................................. 20 Figure 12: Iron & Brick Sleepers.................................................................................................................................................................. 20 Figure 13: Sleeper-less track for the high speed route Nürnberg–Ingolstadt ...................................................................................................... 20 Figure 14: Vertical Alignment ..................................................................................................................................................................... 21 Figure 15: New Mexico: Rail Runner Route to Santa Fe................................................................................................................................. 21 Figure 16: New Mexico: Portion of the new alignment extending along the existing track east of I-25................................................................. 22 Figure 17: New Mexico: Portion of the new alignment entering the I-25 median near the rest area...................................................................... 22 Figure 18: New Mexico: The Santa Fe Southern alignment extending from I-25 to the Santa Fe Railyards .......................................................... 23 Figure 19: Parabolic transition curve as used with the Belgian Railways. This sign aside a railroad (between Ghent and Bruges) indicates the start of the transition curve. A parabolic curve (POB) is used. .......................................................................................................................... 24 Figure 20: Effects of Centrifugal Force ......................................................................................................................................................... 25 Figure 21: Overbalanced, Equilibrium and Under-balanced............................................................................................................................. 25 Figure 22: Cant or Superelevation ................................................................................................................................................................ 26 Figure 23: Cant or Superelevation ................................................................................................................................................................ 26 Figure 24: Cant .......................................................................................................................................................................................... 26 Figure 25: Circular Curve............................................................................................................................................................................ 27 Figure 26: Definition of Degree of Curve D .................................................................................................................................................. 27 Figure 27: Cant Deficiency.......................................................................................................................................................................... 28 Figure 28: Forces bearing on a vehicle.......................................................................................................................................................... 29 Figure 29: Rail head side wear ..................................................................................................................................................................... 30 Figure 30: Twist ......................................................................................................................................................................................... 30 Figure 31: Warp ......................................................................................................................................................................................... 30 Figure 32: System design as a function of train performance, train resistance.................................................................................................... 32 Figure 33: Three Ways to ‘H’ With Coal....................................................................................................................................................... 33 Figure 34: How Much Energy It Takes to Move a Car.................................................................................................................................... 34 Figure 35: Train Resistance ......................................................................................................................................................................... 35 Figure 36: Energy needed to maintain speed, accelerate and curve................................................................................................................... 35 Figure 37: Derivation of Grade Resistance .................................................................................................................................................... 36 Figure 38: Rolling cylinder concept.............................................................................................................................................................. 36 Figure 39: Position of new wheel on new rail ................................................................................................................................................ 37 Figure 40: Possible car/truck attitudes to rail and lateral forces........................................................................................................................ 37 Figure 41: Lateral slippage across rail head ................................................................................................................................................... 38 Figure 42: Comparing the Energy It Takes to Deliver the Goods ..................................................................................................................... 38 Figure 43: Permanent way design flowchart .................................................................................................................................................. 39 Figure 44: Ballasted Section Template.......................................................................................................................................................... 40 Figure 45: Railway Model ........................................................................................................................................................................... 41 Figure 46: Creating tunnels.......................................................................................................................................................................... 41 Figure 47: Visualisation .............................................................................................................................................................................. 42 Figure 48: Driver’s Eye View ...................................................................................................................................................................... 42 Figure 49: Horizontal Regression Points ....................................................................................................................................................... 43 Figure 50: Existing Track Analysis – Display Curvature Cant Diagram and select points for analysis.................................................................. 43 Figure 51: Single Element Regression Analysis ............................................................................................................................................. 44 Figure 52: Design by Curve Set ................................................................................................................................................................... 45 Figure 53: Design by Elements .................................................................................................................................................................... 45 Figure 54: Turnout Schematic...................................................................................................................................................................... 45 Figure 55: Turnout Library .......................................................................................................................................................................... 46 Figure 56: Switch and Crossing behaving like turnout .................................................................................................................................... 46 Figure 57: Switch and Crossing Library ........................................................................................................................................................ 46 Figure 58: Vertical Design - Curves.............................................................................................................................................................. 47 Figure 59: Tools for fabrication and construction detailing.............................................................................................................................. 47 Figure 60: Software tools for track design ..................................................................................................................................................... 48 Figure 61: Alignment design........................................................................................................................................................................ 48 Figure 62: Switch design ............................................................................................................................................................................. 49 Figure 63: Alignment design from surveyed data ........................................................................................................................................... 49 Figure 64: Cross-section design ................................................................................................................................................................... 49 Figure 65: Sub-structure and terrain design ................................................................................................................................................... 50 Figure 66: Presenting .................................................................................................................................................................................. 50 Figure 67: Visualisation .............................................................................................................................................................................. 50
Page 6 of 259
Figure 68: Light rail tracks with concrete railroad ties (sleepers)...................................................................................................................... 51 Figure 69: Shape of Tram Rail ..................................................................................................................................................................... 51 Figure 70: LR55 Section ............................................................................................................................................................................. 52 Figure 71: Rail in Rotherham Bus Station ..................................................................................................................................................... 52 Figure 72: Rail Pressure Graph .................................................................................................................................................................... 53 Figure 73: Grassed Track ............................................................................................................................................................................ 53 Figure 74: Grooved rail gauntlet track on a street tramway in Mannheim, Germany .......................................................................................... 53 Figure 75: Cross-section of the now obsolete bullhead rail.............................................................................................................................. 54 Figure 76: Track using the UK Bullhead rail profile. ...................................................................................................................................... 54 Figure 77: Cross-section of flat-bottomed Vignoles rail .................................................................................................................................. 55 Figure 78: Pandrol clip holding rail to concrete sleeper................................................................................................................................... 56 Figure 79: Trackwork in Jalandhar, India – notice the baseplate and the Pandrol clips ....................................................................................... 56 Figure 80: Pandrol Clip ............................................................................................................................................................................... 57 Figure 81: Spring clip & spike with baseplates on adjacent sleepers at welded joint........................................................................................... 57 Figure 82: Screwed rail attachment............................................................................................................................................................... 57 Figure 83: Traditional British practice at Cardiff Bay railway station shows a fishplate between two sections of jointed bullhead rail with a rail chair screwed into a wooden sleeper. The keys are on the opposite side of the rail (not visible). ........................................................................ 57 Figure 84: BNSF Railway spiker in operation in Prairie du Chien, Wisconsin. The machine is driving spikes on both sides of the rails after the ties were replaced. .................................................................................................................................................................................. 58 Figure 85: Expansion joints are provided in running rails to allow for temperature changes. The additional rails in the centre of the track are bolted to the sleepers to prevent the sleepers being shifted by rail expansion......................................................................................................... 59 Figure 86: Track Joint ................................................................................................................................................................................. 60 Figure 87: Alternative view of track joints..................................................................................................................................................... 60 Figure 88: Rail movement joints with longitudinally moveable stock rails ........................................................................................................ 60 Figure 89: Rail movement joints with longitudinally moveable stock rails ........................................................................................................ 61 Figure 90: Rail Movement Joints "Scarf Type" .............................................................................................................................................. 62 Figure 91: Insulated Joints........................................................................................................................................................................... 62 Figure 92: Continuous Insulated Joint........................................................................................................................................................... 63 Figure 93: Insulated joint with square rail cut ................................................................................................................................................ 63 Figure 94: Insulated joint with angular rail cut............................................................................................................................................... 64 Figure 95: Welded rail joint ......................................................................................................................................................................... 65 Figure 96: GNER_HST_and_Northern_156479_2005-10-08 .......................................................................................................................... 66 Figure 97: Railroad track in Birkenau (Auschwitz II) concentration camp in 2001............................................................................................. 66 Figure 98: Turnout...................................................................................................................................................................................... 67 Figure 99: West_India_Quay_DLR_station_from_Canary_Wharf_DLR_station_2005-12-10............................................................................. 68 Figure 100: Docklands Light Railway junction north of West India Quay......................................................................................................... 68 Figure 101: Left: GNER Intercity 125 HST from Newcastle to Edinburgh via the Tyne Valley Line to Carlisle. Right: Northbound Class 221 Virgin Voyager DEMU heading for Newcaslte. Both trains are crossing the River Tyne on the King Edward VII bridge ....................................... 69 Figure 102: LU-1996ts-Wembley_Park_Siding_2005-12-10 ........................................................................................................................... 69 Figure 103: Netley Railroad......................................................................................................................................................................... 70 Figure 104: Northern_Rail_DMU_156463_at_Sunderland_2005-10-10_03...................................................................................................... 70 Figure 105: Sign of point............................................................................................................................................................................. 71 Figure 106: Silverlink_313123_at_Kensington_Olympia_01 .......................................................................................................................... 71 Figure 107: Taipei MRT railroad point in Damshui Station............................................................................................................................. 72 Figure 108: Welsh Marches Line north of Craven Arms station ....................................................................................................................... 72 Figure 109: "Serna" junction station turnout (Salamanca) ............................................................................................................................... 73 Figure 110: "Serna" junction station – symmetrical turnout............................................................................................................................. 73 Figure 111: "Serna" junction station: Convergent switch................................................................................................................................. 74 Figure 112: Castle Cary railway station – view west from footbridge ............................................................................................................... 74 Figure 113: Castle Cary railway station - view west from footbridge................................................................................................................ 75 Figure 114: View west from Castle Cary railway station................................................................................................................................. 75 Figure 115: Castle_Cary_railway_station_viewed_from_car_park_-_02 .......................................................................................................... 76 Figure 116: Carlisle_railway_station_2005-10-08_01..................................................................................................................................... 76 Figure 117: Bristol-Birmingham-Derby Line north of Filton Abbey Wood ....................................................................................................... 77 Figure 118: Which way? ............................................................................................................................................................................. 77 Figure 119: Westbound freight train at Bristol Parkway.................................................................................................................................. 78 Figure 120: Boldon West Junction................................................................................................................................................................ 78 Figure 121: Variety of railroad turnouts ........................................................................................................................................................ 79 Figure 122: A scene from Indian Railways .................................................................................................................................................... 79 Figure 123: Compensate to maintain tension in the cables that work the switches.............................................................................................. 80 Figure 124: Typical track plan of a turnout.................................................................................................................................................... 80 Figure 125: Typical Vossloh Turnout Components......................................................................................................................................... 81 Figure 126: Turnout Zones .......................................................................................................................................................................... 81 Figure 127: Simple turnout with names of principal parts ............................................................................................................................... 82 Figure 128: This detail of a switch shows the pair of tapered moveable rails known as the switch points (switch rails or point blades).................... 82 Figure 129: Mathematical Representation of a Frog ....................................................................................................................................... 83 Figure 130: Frog Crossing ........................................................................................................................................................................... 83 Figure 131: A flangeway ............................................................................................................................................................................. 83 Figure 132: Frog......................................................................................................................................................................................... 84 Figure 133: Frog in abandoned station in Spain ............................................................................................................................................. 85 Figure 134: Cast frog .................................................................................................................................................................................. 86
Page 7 of 259
Figure 135: Old mounted frog with cast middle ............................................................................................................................................. 86 Figure 136: Mounted frog............................................................................................................................................................................ 87 Figure 137: A cast manganese crossing/frog in a standard UK turnout. Special baseplates have to be provided at turnouts for switch blades, check rails and crossing work. ..................................................................................................................................................................... 87 Figure 138: mounted frog with welded point ................................................................................................................................................. 88 Figure 139: Functioning of Guard / Check Rail.............................................................................................................................................. 89 Figure 140: Check gauge............................................................................................................................................................................. 89 Figure 141: Check / Guard Rail.................................................................................................................................................................... 89 Figure 142: Guard Rail................................................................................................................................................................................ 90 Figure 143: The frog (left) and guard rail (right) can be seen in this detail of a switch. ....................................................................................... 91 Figure 144: Extended wing rail as the check rail ............................................................................................................................................ 91 Figure 145: Double frog with check rail........................................................................................................................................................ 92 Figure 146: The railroad switch with joints, designed for manual operation. The enlarged part (right bottom corner) show the joint construction. Military railway near Dubendorf, Switzerland...................................................................................................................................... 92 Figure 147: This rigid, ground-throw switch machine on the Horovitz's Ogden Botanical Railway is designed to hold the points against one rail or the other, so that trains can pass smoothly through. The machine is rigidly attached to the throw bar to firmly set the points against the stock rails. ....................................................................................................................................................................................................... 93 Figure 148: Railway turnout with electric throw ............................................................................................................................................ 93 Figure 149: dovetail-shaped locking of the switch blades in opened position .................................................................................................... 94 Figure 150: Hand-Throw Switch Stands........................................................................................................................................................ 94 Figure 151: Turnout Indicators..................................................................................................................................................................... 95 Figure 152: High-Switch Targets ................................................................................................................................................................. 96 Figure 153: Switch Targets.......................................................................................................................................................................... 96 Figure 154: Targets used by the Denver & Rio Grande Western ...................................................................................................................... 97 Figure 155: Positive “closed” aspect............................................................................................................................................................. 97 Figure 156: Michigan Central Switch Targets................................................................................................................................................ 98 Figure 157: Grafik_weichensignal................................................................................................................................................................ 98 Figure 158: Switch Stand ............................................................................................................................................................................ 99 Figure 159: Switch Stand ............................................................................................................................................................................ 99 Figure 160: Switch Stand .......................................................................................................................................................................... 100 Figure 161: Switch Stand .......................................................................................................................................................................... 100 Figure 162: Switch Stand .......................................................................................................................................................................... 101 Figure 163: The mechanism used in a switch stand. The two points are locked together with a bar between them. This bar continues to the lever on the near side of the tracks which is used to throw the switch (North American usage). This is an example of a low switch stand, used at locations where there is not sufficient clearance for a tall switch stand. This particular stand is designed to be trailed through by rolling stock, which will cause the points to become lined for the route that the wheels have passed through. It has a reflectorised target. ....................... 102 Figure 164: A manual lock (type HV73) of a point at the railway station of Kinding, Nürnberg–Ingolstadt high-speed railway line...................... 102 Figure 165: A ground-frame with a few hand-operated point levers for manually operating nearby points at Bristol Temple Meads. .................... 103 Figure 166: Hand-operated crank-type points-machine at Sukeva, Finland ..................................................................................................... 103 Figure 167: Hand-operated point levers at the now defunct Wakayanagi station, Japan .................................................................................... 104 Figure 168: Switch Reversing Lever........................................................................................................................................................... 104 Figure 169: Switch Reversing Lever........................................................................................................................................................... 105 Figure 170: Retired old switches of the station of The Palms, after their remodelling. ...................................................................................... 105 Figure 171: Switch Reversing Lever........................................................................................................................................................... 106 Figure 172: Typical Spanish switches with switch reversing levers and switchpoint lamps on sidetracks ........................................................... 106 Figure 173: Typical Spanish switches with switch reversing levers and switchpoint lamps on sidetracks ........................................................... 107 Figure 174: Switch Reversing Lever........................................................................................................................................................... 107 Figure 175: Davle, the Czech Republic ....................................................................................................................................................... 108 Figure 176: Manual point lever .................................................................................................................................................................. 108 Figure 177: Onda Point Machine................................................................................................................................................................ 109 Figure 178: Switch Reversing Lever........................................................................................................................................................... 109 Figure 179: Switch Reversing Lever........................................................................................................................................................... 110 Figure 180: Railway turnout with electric point machine .............................................................................................................................. 111 Figure 181: An electric switch motor and associated mechanism used to operate this switch. A closeup of the converging points immediately north of w:Filton Abbey Wood railway station. In this configuration the track is set for trains from Bristol Parkway. ............................................ 111 Figure 182: An electric switch motor and associated mechanism used to operate this switch. A closeup of the converging points immediately north of w:Filton Abbey Wood railway station. In this configuration the track is set for trains from w:South Wales or Avonmouth via Brentry........ 112 Figure 183: RENFE Motor Points in VIGO Station ...................................................................................................................................... 112 Figure 184: An electric point machine located adjacent to the switch blades it operates. Most point machines are electrically operated though London Underground still has a large number of air operated machines. ........................................................................................................... 113 Figure 185: Automatic Switch Drive .......................................................................................................................................................... 113 Figure 186: Automatic Switch Drive .......................................................................................................................................................... 114 Figure 187: Switch Reversing Lever........................................................................................................................................................... 115 Figure 188: Switch Reversing Lever........................................................................................................................................................... 115 Figure 189: US turnout showing the electro-pneumatic motor to operate the switchblades and the point heater tube alongside the stock rail. Heaters are invaluable in cold weather conditions and are widely used. Turnout motors are usually electric but electro-pneumatic motors are seen in the US and are standard equipment for London Underground.................................................................................................................... 116 Figure 190: "Serna" junction station turnout (Salamanca) ............................................................................................................................. 116 Figure 191: "Serna" junction station turnout (Salamanca) ............................................................................................................................. 117 Figure 192: AZP Praha EP 600 electronic point machine .............................................................................................................................. 117 Figure 193: EP 600 electronic point machine hollow sleeper ......................................................................................................................... 118
Page 8 of 259
Figure 194: Fixing the point machine in the hollow sleeper........................................................................................................................... 118 Figure 195: Facing & Trailing.................................................................................................................................................................... 119 Figure 196: Animated diagram of a right-hand railroad switch, rail track A divides into two: track B (the straight track) and track C (the diverging track) ............................................................................................................................................................................................. 119 Figure 197: The operation of a railroad switch. ............................................................................................................................................ 120 Figure 198: Switch Right........................................................................................................................................................................... 121 Figure 199: Switch Left............................................................................................................................................................................. 121 Figure 200: Switch Right........................................................................................................................................................................... 121 Figure 201: Switch Left............................................................................................................................................................................. 121 Figure 202: Switch Right – Check Rail ....................................................................................................................................................... 122 Figure 203: Switch Left – Check Rail ......................................................................................................................................................... 122 Figure 204: Switch Right........................................................................................................................................................................... 122 Figure 205: Switch Left............................................................................................................................................................................. 122 Figure 206: Switch Right........................................................................................................................................................................... 122 Figure 207: Switch Right........................................................................................................................................................................... 122 Figure 208: Switch Left............................................................................................................................................................................. 122 Figure 209: Switch Left............................................................................................................................................................................. 122 Figure 210: A right-hand railroad switch in Oulu, Finland. The facing points are set to divert. From the opposite direction they would be trailing points............................................................................................................................................................................................. 123 Figure 211: A left-hand railroad switch....................................................................................................................................................... 123 Figure 212: Trailing Point Movement ......................................................................................................................................................... 124 Figure 213: A left-hand railroad switch....................................................................................................................................................... 124 Figure 214: Self-Regulating Switchpoint Rail Heaters .................................................................................................................................. 125 Figure 215: Gas heating keeps a switch free from snow and ice. .................................................................................................................... 125 Figure 216: Benicassim's station, works to install a leak in the exit towards Castellon...................................................................................... 126 Figure 217: Benicassim's station, leak already installed in the exit towards Castellon....................................................................................... 127 Figure 218: Benicassim's station, leak already installed in the exit towards Castellon....................................................................................... 128 Figure 219: Applications of turnouts........................................................................................................................................................... 130 Figure 220: Single slip switch .................................................................................................................................................................... 130 Figure 221: Double slip switch................................................................................................................................................................... 130 Figure 222: On prototype and model railroads alike, curved switches are built where space is at a premium. This dual-gauge (0 and 1 gauge) curved switch is on Marc Horovitz’s Ogden Botanical Railway. Dual-gauge switches are considerably more complex than single-gauge switches, but their operation is identical. ............................................................................................................................................................... 131 Figure 223: A three-way switch allows trains to go either to the left, right, or straight. Notice there are two sets of points imbedded in this example from Jim Strong’s Woodland Railway............................................................................................................................................... 131 Figure 224: A double-slip switch is perhaps the most complex switch there is. Operationally, it’s four switches in one, each crossing over the other, so that trains can run onto any track. ................................................................................................................................................. 131 Figure 225: Scissors crossover in CMS (Indian Railways) ............................................................................................................................ 132 Figure 226: Scissors or Diamond Crossover ................................................................................................................................................ 132 Figure 227: A scissors crossover: two pairs of switches linking two tracks to each other in both directions ........................................................ 133 Figure 228: Carlisle railway station ............................................................................................................................................................ 133 Figure 229: Crossrails at Leeds .................................................................................................................................................................. 134 Figure 230: Cambridge-longplatform-north-04 ............................................................................................................................................ 134 Figure 231: Level Junction with Scissors (Diamond) Crossover .................................................................................................................... 135 Figure 232: Stockport Edgeley with awkward (scissors) crossover in foreground. ........................................................................................... 135 Figure 233: Crossrails at Leeds .................................................................................................................................................................. 136 Figure 234: Scissors crossover – fully welded construction ........................................................................................................................... 137 Figure 235: A double slip switch at Munich Central ..................................................................................................................................... 138 Figure 236: A double slip switch ................................................................................................................................................................ 139 Figure 237: A double slip switch – “English” Connection............................................................................................................................. 139 Figure 238: Double slip switch with Cauer Indicator .................................................................................................................................... 140 Figure 239: Slip switch ............................................................................................................................................................................. 140 Figure 240: Junction south of Wilkinson Street tram stop ............................................................................................................................. 141 Figure 241: Double slip switch operation .................................................................................................................................................... 141 Figure 242: Double slip switches................................................................................................................................................................ 142 Figure 243: A double slip switch at a factory ............................................................................................................................................... 142 Figure 244: A double slip switch at a factory ............................................................................................................................................... 143 Figure 245: A single slip switch ................................................................................................................................................................. 144 Figure 246: A single slip switch ................................................................................................................................................................. 145 Figure 247: A double, outside slip in Heidelberg main station ....................................................................................................................... 145 Figure 248: A Narrow Gauge Stub-Switch .................................................................................................................................................. 146 Figure 249: Stub Switch ............................................................................................................................................................................ 146 Figure 250: A Narrow Gauge Plate Switch .................................................................................................................................................. 147 Figure 251: A three-way stub switch at Sheepscot station on the Wiscasset, Waterville and Farmington Railway ............................................... 147 Figure 252: A three-way switch formerly at Brisbane's Light Street tram depot now on display at the Brisbane Tramway Museum...................... 148 Figure 253: Three-way Stub Switch............................................................................................................................................................ 148 Figure 254: Interlaced Turnout................................................................................................................................................................... 149 Figure 255: Gantlet Track.......................................................................................................................................................................... 149 Figure 256: Gantlet Track.......................................................................................................................................................................... 150 Figure 257: Passing Track ......................................................................................................................................................................... 151 Figure 258: Wye Switch............................................................................................................................................................................ 152
Page 9 of 259
Figure 259: Sefton Station: Double track triangle, drawn in one-rail style....................................................................................................... 152 Figure 260: A Wye.One approach to this wye has been abandoned, but it and the two remaining legs are still visible. ........................................ 152 Figure 261: Wye Switch – Symmetrically diverging..................................................................................................................................... 152 Figure 262: Diagram showing the use of trap points to protect the main line at the exit of a siding .................................................................... 153 Figure 263: Trap Point .............................................................................................................................................................................. 154 Figure 264: Trap Points located to protect a main line track from vehicles moving past the shunt limit board and causing an obstruction. Note the mix of concrete and wooden sleepers....................................................................................................................................................... 155 Figure 265: A trap point with buffer stops at the train station of Allersberg, Nuremberg-Munich high-speed railway line. This is a safety device that would lead a train to the buffer at the right, in the unlikely event that the engineer passes by the red signal before the switch. Such trap point railway switches are obligatory for high-speed railway lines (v_max > 160 km/h) in Germany................................................................ 155 Figure 266: Double trap points with much longer rails, at Castle Cary railway station. See the two-level baseplates under the rising turnout rail, and also the inner rail stops short of an extended check rail ....................................................................................................................... 156 Figure 267: Double trap points protecting the South Wales Main Line at the exit of Stoke Gifford Rail Yard near Bristol Parkway railway station 156 Figure 268: Catch Point............................................................................................................................................................................. 157 Figure 269: Catch points operation ............................................................................................................................................................. 158 Figure 270: Catch point at Springwell......................................................................................................................................................... 158 Figure 271: Another catch point at Springwell ............................................................................................................................................. 159 Figure 272: An insulated track circuit interrupter fitted to trap points. ............................................................................................................ 159 Figure 273: Interrupter drawn as two filled triangles. Assume train has overrun 53 signal and 52A trap points and interrupter shows DBT T.C. on Down Line as blocked (twin red lights) ............................................................................................................................................. 160 Figure 274: Trap points and a sand drag protect the exit of a station passing loop (left), while catch points stop vehicles from running away down a steep slope (right) ........................................................................................................................................................................... 161 Figure 275: Derailer.................................................................................................................................................................................. 162 Figure 276: Derailer.................................................................................................................................................................................. 163 Figure 277: Dual-Gauge Switch ................................................................................................................................................................. 163 Figure 278: High Speed Turnout ................................................................................................................................................................ 164 Figure 279: Rotary switch in operation at summit station of Pilatus Railway................................................................................................... 164 Figure 280: Voest Alpine Metro and Tram Turnouts .................................................................................................................................... 164 Figure 281: Substitution track switch for rail at Chester Zoo - Switching Section on the Monorail ride.............................................................. 165 Figure 282: Heavy Haul turnouts................................................................................................................................................................ 165 Figure 283: A one-piece cast frog. The shiny line crosses the rusty line. This is an example of North American "self-guarding cast manganese" frog, where guard-rails are not used, the raised flanges on the frog bearing on the face of the wheel as it passes through the frog. ...................... 166 Figure 284: VAE crossing with moveable point and manganese base plate ..................................................................................................... 167 Figure 285: A switched crossing ................................................................................................................................................................ 167 Figure 286: A moveable point frog (swingnose crossing).............................................................................................................................. 167 Figure 287: Swingnose crossing operation .................................................................................................................................................. 168 Figure 288: Thick Web Switches................................................................................................................................................................ 168 Figure 289: Trailable turnout with clamp lock and recoiling cylinder ............................................................................................................. 169 Figure 290: Self-regulating clamp lock ....................................................................................................................................................... 169 Figure 291: Turnout.................................................................................................................................................................................. 171 Figure 292: Curve Beyond Frog ................................................................................................................................................................. 172 Figure 293: Mechanical Interlocking 1 of 12 ............................................................................................................................................... 175 Figure 294: Mechanical Interlocking 2 of 12 ............................................................................................................................................... 176 Figure 295: Mechanical Interlocking 3 of 12 ............................................................................................................................................... 176 Figure 296: Mechanical Interlocking 4 of 12 ............................................................................................................................................... 177 Figure 297: Mechanical Interlocking 5 of 12 ............................................................................................................................................... 177 Figure 298: Mechanical Interlocking 6 of 12 ............................................................................................................................................... 178 Figure 299: Mechanical Interlocking 7 of 12 ............................................................................................................................................... 178 Figure 300: Mechanical Interlocking 8 of 12 ............................................................................................................................................... 179 Figure 301: Mechanical Interlocking 9 of 12 ............................................................................................................................................... 179 Figure 302: Mechanical Interlocking 10 of 12.............................................................................................................................................. 180 Figure 303: Mechanical Interlocking 11 of 12.............................................................................................................................................. 180 Figure 304: Mechanical Interlocking 12 of 12.............................................................................................................................................. 181 Figure 305: This is how points work........................................................................................................................................................... 182 Figure 306: This is what happened ............................................................................................................................................................. 182 Figure 307: This is what happened ............................................................................................................................................................. 183 Figure 308: The crash site.......................................................................................................................................................................... 183 Figure 309: Derailment of train EC 107 (Prague-Warsaw) in Prague on 17th Feb 07. Broken switch tongue was reason of derailment.................. 184 Figure 310: Derailment of train EC 107 (Prague-Warsaw) in Prague on 17th Feb 07. Broken switch tongue was reason of derailment.................. 185 Figure 311: Abergele Train Disaster ........................................................................................................................................................... 185 Figure 312: Junction ................................................................................................................................................................................. 187 Figure 313: World's most complicated railway crossing – Frankfurt Germany ................................................................................................ 187 Figure 314: Flying junction: with a bridge, trains do not block each other....................................................................................................... 188 Figure 315: Fretin triangle, France: Each side is over 3 km (2 mi) long. TGVs and Eurostars cross it at 300 km/h (186 mph) .............................. 188 Figure 316: Flat junction: trains have to wait to cross the 'diamond' at the centre ............................................................................................. 189 Figure 317: A schematic diagram of a dual-gauge diamond crossing.............................................................................................................. 189 Figure 318: Central Trains diesel multiple unit on a Nottingham-Derby-Stoke train arrives across London Road Junction, Derby 21st Sept 2005. The junction pointwork is still quite complex with several diamond crossings.............................................................................................. 189 Figure 319: This 'rotten' diamond crossing has recently been reduced from 50 kph to 30 kph, any wonder !!!! ................................................... 190 Figure 320: Unusual prefab 2 ft gauge diamond crossing .............................................................................................................................. 190 Figure 321: Railroad crossing at grade, also known as a diamond crossing or level junction. This example is located in Mulberry, Florida. .......... 191
Page 10 of 259
Figure 322: Components of an abandoned level junction assembly ................................................................................................................ 191 Figure 323: A temporary level junction. This allows Sacramento Southern Railroad trains to pass over the Union Pacific tracks in Sacramento, California. The components must be installed, railroad cars moved, and the assembly dismantled in less than 30 minutes so as not to impede UPRR freight and Amtrak passenger train movement along the main line. ............................................................................................ 192 Figure 324: Diamond (level) crossing in Ratlam, India ................................................................................................................................. 192 Figure 325: A fully assembled level junction in the foreground. .................................................................................................................... 193 Figure 326: The Brickworks at Ledo, Assam. The narrow gauge line crosses our road and then the broad gauge tracks too. Note the diamond crossing of the BG and NG lines in the foreground. the line beyond into the brickwork complex seems to have been ripped off, and the gate walled up. ..................................................................................................................................................................................................... 194 Figure 327: Lap Beam Manganese Diamond Crossings AMS (Austenitic Manganese Steel) ............................................................................ 195 Figure 328: Diamond crossing with cast manganese frogs............................................................................................................................. 195 Figure 329: Train crossing a diamond crossing ............................................................................................................................................ 196 Figure 330: Double junction at Bedford ...................................................................................................................................................... 196 Figure 331: Double Junction with Diamond ................................................................................................................................................ 197 Figure 332: A switched diamond with two swingnose crossings at a UK junction............................................................................................ 197 Figure 333: Double Junction with Switched Diamond .................................................................................................................................. 197 Figure 334: Double Junction with Ladders .................................................................................................................................................. 198 Figure 335: Double Junction with Single Lead............................................................................................................................................. 198 Figure 336: Double Junction with Diamond & Wide Centres ........................................................................................................................ 198 Figure 337: Double Junction with Flyover................................................................................................................................................... 199 Figure 338: Chatswood Junction ................................................................................................................................................................ 199 Figure 339: Grand Union........................................................................................................................................................................... 199 Figure 340: The '0 kilometre peg' marks the start of a branch line in Western Australia.................................................................................... 200 Figure 341 Platform 1 is for trains north and east bound, platform 2 is for trains south and west bound ............................................................. 201 Figure 342: Rail Siding ............................................................................................................................................................................. 204 Figure 343: Passing Loop .......................................................................................................................................................................... 204 Figure 344: Funicular Passing Loop ........................................................................................................................................................... 205 Figure 345: Crossing Loop – Main & Loop Working ................................................................................................................................... 205 Figure 346: Crossing Loop – Platform & Through Working.......................................................................................................................... 205 Figure 347: Crossing Loop – Up and Down Working ................................................................................................................................... 206 Figure 348: Crossing Loop – Left Hand Working ........................................................................................................................................ 206 Figure 349: Double sided island platform on a balloon loop .......................................................................................................................... 207 Figure 350: South Ferry balloon loop.......................................................................................................................................................... 207 Figure 351: Brooklyn Bridge and City Hall stations in New York City........................................................................................................... 208 Figure 352: Platform track and run-round loop at Toyooka Station, Hyōgo, Japan, the terminus of the line from Miyazu .................................... 209 Figure 353: Eastleigh_rail_yard_1984 ........................................................................................................................................................ 210 Figure 354: Badarpur Yard, Assam, India ................................................................................................................................................... 211 Figure 355: Final approach over a massive rail yard immediately adjacent to O'Hare Airport, with downtown Chicago in the distance ................. 211 Figure 356: A Typical Yard (Depot) ........................................................................................................................................................... 212 Figure 357: Another Yard (Depot).............................................................................................................................................................. 213 Figure 358: A switch engine pushes a car over the hump .............................................................................................................................. 214 Figure 359: The retarders grip the sides of the wheels on passing cars to slow them down................................................................................ 215 Figure 360: Typical Side Platform Station Layout........................................................................................................................................ 216 Figure 361: Side platforms with overpass between them ............................................................................................................................... 216 Figure 362: Jordanhill railway station with two side platforms, and a footbridge connecting them..................................................................... 217 Figure 363: Typical Elevated Side Platform Station Layout .......................................................................................................................... 217 Figure 364: Elevated Station with Ticket Hall below platforms ..................................................................................................................... 218 Figure 365: Typical Island Platform Layout ................................................................................................................................................ 218 Figure 366: Schematic of Island Platform.................................................................................................................................................... 218 Figure 367: A station with island platform................................................................................................................................................... 219 Figure 368: Underground island platform: Clapham Common Tube Station north and south-bound platforms on the Northern Line, in London, England ......................................................................................................................................................................................... 219 Figure 369: A bay platform at Nottingham railway station ............................................................................................................................ 220 Figure 370: The Principle of the Spanish Solution........................................................................................................................................ 221 Figure 371: A diagram of how a paired cross-platform interchange works ...................................................................................................... 222 Figure 372: Passengers interchange (between the Central Line and 'one' train service at Stratford station in London, England.) ........................... 222 Figure 373: Platform screen (edge) doors are provided on the Jubilee Line stations. The operation of the doors is synchronised with those on the train. Here the driver aligns the train with the doors to within +/- 250 mm in order for the doors to open, though in most modern cases the doors are automatically aligned....................................................................................................................................................................... 223 Figure 374: Platform screen doors at Serangoon MRT Station in Singapore’s North East Line ......................................................................... 223 Figure 375: Satellite view of Horseshoe Curve, west of Altoona, Pennsylvania. Trains headed counterclockwise around the curve are going uphill. ..................................................................................................................................................................................................... 225 Figure 376: Panorama of the Pennsylvania Railroad's Horseshoe Curve ......................................................................................................... 225 Figure 377: A Spiral ................................................................................................................................................................................. 227 Figure 378: Loop (Agony Point) on the Darjeeling Himalayan Railway, India ................................................................................................ 227 Figure 379: A buffer stop .......................................................................................................................................................................... 229 Figure 380: This southerly view (10/8/06) shows the temporary buffer stop and loop at Traeth Mawr at the end of the 900m Extension from Pen-yMount. The point lever at this end remains to be fitted. ....................................................................................................................... 230 Figure 381: 47972 stands at the buffer stops at London St Pancras after arriving with a HST replacement service on 04/01/93, the train was the 1523 ex Sheffield..................................................................................................................................................................................... 230 Figure 382: At Queensland Railways maintenance yard at Banyo the siding comes to an end at the buffer stop. ................................................. 231
Page 11 of 259
Figure 383: Two views of a Hayes-built bumper at the Linden Railroad Museum, Linden, Indiana. .................................................................. 232 Figure 384: Energy-absorbing buffer stop in France ..................................................................................................................................... 232 Figure 385: Buffer stop at Zurich Main Station track 54. The buffer stop is designed to move up to 7 m to slow down a 850 t passenger train from 15 km/h without damaging the train or injuring passengers. ..................................................................................................................... 233 Figure 386: The aftermath of the Gare Montparnasse accident....................................................................................................................... 234 Figure 387: An automatic level crossing in France, with half-barriers, flashing lights and a bell........................................................................ 235 Figure 388: A fence or chicane may prevent pedestrians running across the track............................................................................................ 235 Figure 389: Flangeway timber road crossing ............................................................................................................................................... 236 Figure 390: A traditional mechanical crossing bell ....................................................................................................................................... 239 Figure 391: A level crossing sign on the Romney, Hythe and Dymchurch Railway at St Mary's Bay railway station, UK.................................... 240 Figure 392: A manually operated level crossing in Siliguri, India. ................................................................................................................. 240 Figure 393: Europe uses a St Andrew's Cross to warn road users ................................................................................................................... 240 Figure 394: Crossbuck with white background and black lettering ................................................................................................................. 241 Figure 395: International Variants of the Crossbuck ..................................................................................................................................... 241 Figure 396: Multiple tracks at a crossbuck .................................................................................................................................................. 241 Figure 397: Rail Gauge ............................................................................................................................................................................. 242 Figure 398: Railway gauges around the world ............................................................................................................................................. 242 Figure 399: Comparison of standard gauge (blue) and one common narrow gauge (red) width ......................................................................... 247 Figure 400: Switch - bifurcation of dual-gauge track near Jindřichův Hradec, Czech Republic.......................................................................... 253 Figure 401: Dual gauge dual voltage........................................................................................................................................................... 255 Figure 402: A dual-gauge track (Iberic: 1668mm-5ft6in; Standard: 1435mm-4ft8in) seen at Huesca station....................................................... 255 Figure 403: Bogies exchange operation in Ussurisk (near Vladivostok) at the Chinese–Russian border. ............................................................ 256 Figure 404: One solution to the break-of-gauge problem – the transporter car ................................................................................................. 257
Page 12 of 259
1
Introduction
1.1 The Track
Figure 1: Rail Track Components
Rail Tracks or Permanent Way means the physical elements of the railway line itself: generally the pairs of rails typically laid on sleepers ("crossties" or just "ties", in North America) embedded in ballast, intended to carry the ordinary trains of a railway. It is described as permanent way because in the earlier days of railway construction, contractors often laid a temporary track to transport spoil and materials about the site; when this work was substantially completed, the temporary track was taken up and the permanent way installed. The track is a fundamental part of the railway infrastructure and represents the primary distinction between this form of land transportation and all others in that it provides a fixed guidance system. It is the steering base for the train and has evolved from an ancient design of vehicle guidance with origins dating, some historians have suggested, from the Sumerian culture of 2000 BC. The modern railway version is based on hardened steel wheels running on a pair of hardened steel rails as the base. Other forms of guided vehicle technology - rubber-tyred trains, magnetic levitation and guided bus ways - also exist. Steel rails can carry heavier loads than any other material. The traditional form of Permanent Way consists of:
two parallel iron or steel rails, a fixed distance apart, on which the wheels of trains run, transverse beams called sleepers, set at a close spacing, that maintain the specified spacing of the rails and that distribute the concentrated loading of train wheels, fastenings to hold the rails and sleepers together, a layer of mineral ballast placed under and around the sleepers, to further distribute the train loading, and to resist lateral displacement
Parallel steel rails forming tracks together with railroad switches (or points) guide trains without the need for steering. Rails are laid upon sleepers (ties) embedded in ballast to form the railroad track. Railroad ties spread the load from the rails over the ground and serve to hold the rails a fixed distance apart called the gauge, always measured between the inner faces of the rails. The rail is fastened to the ties with rail spikes, lag screws or clips such as Pandrol clips. The type of fastener depends partly on the type of sleeper, with spikes being used on wooden sleepers, and clips being used more on concrete sleepers. Usually, a base plate (or fishplate, although a fishplate is also a bar used to join rails) is used between the rail and wooden sleepers to spread the load of the rail over a larger area of the sleeper. Sometimes spikes are driven through a hole in the base plate to hold the rail, while at other times the base plates are spiked or screwed to the sleeper and the rails clipped to the base plate.
1.2 The Sub-Structure
Page 13 of 259
Figure 2: The Sub-Structure
The track is the most obvious part of a railway route but there is a sub-structure supporting it which is very important in ensuring safe and comfortable rides for passengers or freight in a train. The total width across the two-track alignment could be 15 m (50 ft) for a modern formation. This part of the railroad consists of three main elements: the formation (sub-grade), the sub-ballast and the ballast. The formation is the ground upon which the track will be laid. It can be the natural ground level or "grade" or it can be an embankment or cutting. It is important that the formation is made of the right materials and is properly compacted to carry the loads of passing trains. The purpose of sub-ballast is to form a transition zone between the ballast and sub-grade to avoid migration of soil into the ballast and to reduce the stresses applied to the sub-grade. The formation under the track has a "camber" rather like that seen on a roadway. This is to ensure ease of water run-off to the drains provided on each side of the line. The track itself is supported on "ballast", made up of stones - usually granite or, in the US, basalt - below which is a layer of sand, which separates it from the formation. For new or renewed formations, the sand is normally laid over some sort of geotechnical screen or mesh to separate it from the foundation material below. In the past, asphalt or plastic sheeting has been used to prevent water seepage.
Figure 3: The main parts of an electrified double-track line.
Catenary masts (if the line is electrified on the overhead system) are located outside the drains and beyond them there is a walkway area. The "cess" shown each side of the alignment is the area available for a walkway or refuge for staff working on the track. This may just be a cleared path for staff to walk safely, avoiding passing trains or, on modernised routes, a properly constructed path. Next to this path will be a cable trough. These were originally concrete but are nowadays often made of plastic. A plastic tube, usually bright orange in the UK, protects cables crossing the track. Proper
Page 14 of 259
cable protection is essential to prevent damage by animals, track maintenance tools, weather and fire. Usually the edge of the railway property is outside the pathway or cable runs. Railroads do not always run on plains but would often experience combinations of high or low grounds to travel on. In order to keep a road or rail line straight and/or flat, and where the comparative cost or practicality of alternate solutions (such as diversion) is too prohibitive, a piece of a hill or mountain is cut out to make way for it. A cutting in construction is usually blasted out with carefully placed explosives. The cutting may only be on one side of a slope or directly through the middle or top of a hill. Generally, a cutting is open at the top (otherwise it is a tunnel). An embankment is (in a sense) the opposite of a cutting. In order to carry a railway over an area of low ground and to keep it straight and/or flat, and where the comparative cost or practicality of alternate solutions (such as diversion) is too prohibitive, a natural or artificial slope called an embankment is built up of earth, stones or bricks, or a combination of these over which the railway line will travel. An embankment is often constructed using material obtained from a cutting. If the line is built through an area requiring an embankment or cutting, the slopes will be carefully designed to ensure that the angle of slope will not take an excessive width of land and allow proper drainage but without risking an earth slip. The slope angle depends on the type of soil available, the exposure, the climate and the vegetation in the area. Drainage ditches are often added along the edges of cuttings and embankments. In the UK, fences are always provided along the boundary line of the railway to protect the public from wandering onto the track. Even so, there are a few accidents every year when trespassers are killed or injured by trains or electric conductor rails. Many countries around the world don't fence their railways, assuming people will treat them like roads and look both ways before crossing. They don't!
Figure 4: Cuttings
Figure 5: Embankments
1.2.1
Ballasted vs. Non-Ballasted (Slab) Track
Rail tracks are normally laid on a bed of coarse stone chippings known as ballast, which combines resilience, some amount of flexibility, and good drainage. Steel rails can also be laid onto a concrete slab (a slab track). Across bridges, track is often laid on ties across longitudinal timbers (referred to as "wheeltimbers" or "waybeams") or longitudinal steel girders. The basic argument for different track designs will be based on the bottom line - cost: cost of installation and cost of maintenance. There are however, other issues such as environment - noise, dust and vibration - or engineering issues such as space, location, climate and the type of service intended for the track. Rail tracks are normally laid on a bed of coarse stone chippings known as ballast, which combines resilience, some amount of flexibility, and good drainage. Steel rails can also be laid onto a concrete (slab) track. Across bridges, tracks are often laid on ties across longitudinal timbers or longitudinal steel girders. Track ballast forms the track bed upon which railway sleepers (ties) are laid. It is used to create an even running surface, provide support and hold tracks in place as trains move, transfer load and provide drainage thereby keeping water away from rails and sleepers. Ballast must support the weight of the track and the considerable cyclic loading of passing trains (Individual loads on rails can be as high as 50 tonnes (55 US or short tons) and around 80 short tons on a heavy haul freight line.)
Page 15 of 259
Ballast is made up of heavy crushed stones of granite or similar material rough in shape to improve the locking of stones and better resist movement, since ballast stones with smooth edges do not work so well. However, on lines with lower speeds and weight, gravel, sand and even ash (cinders) from the fires of coal-fired steam locomotives have been used. In the early days of railroads in the United States, much material for ballast came from rock found in the local area. In the Midwest much use was made of quartzite, while states in the southeast, such as Florida, made use of limestone. One specific type of quartzite used there earned the name "Pink Lady" due to its colour; in other areas, the ballast can be a mix of light and dark colours called "Salt and Pepper". Ballast is laid up to a depth of 9 to 12 inches (up to 300 mm on a high speed track) and weighs about 1,600 to 1,800 kg/cu/m. There are a wide variety of track forms and systems incorporating some form of concrete base or support, which doesn't need ballast. Almost all of these require less depth of construction than ballasted track. However, the accuracy of installation must be higher than that needed for ballasted track. Slab track will not be adjusted after installation but ballast can be packed to align track as required. There is now a range of modern track forms using concrete base. They are generally used in special locations such as tunnels, viaducts or bridges where a rigid base is required to ensure track stability in relation to the surrounding structures. An important alternative to the standard track type described above is slab track, sometimes referred to as ballast-less track. In this variant the sleepers and ballast are replaced by a concrete (or asphalt) slab. A number of alternative types have been adopted, including
Ladder track, in which the rails are supported on pre-cast concrete longitudinal bearers with concrete transoms to keep gauge; A continuously placed in-situ slab in which the fastening inserts are formed before the slab concrete cures (known as the PACT system). Cast-in sleeper track, in which concrete sleepers are fixed in an in-situ concrete slab. The sleepers in this system usually have protruding reinforcing bars extending into the in-situ concrete to provide a shear key.
Installing slab track is generally more expensive than ballasted track and it requires lengthy track possessions to install it properly (some skimped installations have failed in service and they proved very difficult and expensive to rectify), but maintenance costs are reduced drastically and the life time of the structure is significantly larger. In consequence slab track has not found widespread adoption in Britain, and the relatively few examples are installed in special-case situations.
The ability of ballast to allow track realignment is one of its most serious weaknesses. The lateral movement caused by passing trains on curved track is one of the major causes of maintenance costs added to which is the crushing caused by axle weight and damage due to weather and water. Ballast damage leads to tracks "pumping" as a train passes and, eventually, rail or sleeper damage will occur, to say nothing of the reduced comfort inside the train and the additional wear on rolling stock. Apart from regular repacking or "tamping", ballast will have to be cleaned or replaced every few years. Another aspect to the ballasted track design, is the dust which is caused during installation and as it wears or gets crushed. It does however offer a useful sound deadening quality. Fixed track formations using slab track or a concrete base of some sort do not suffer from such problems. However, the installation of slab track is reported to cost about 20% more than ballasted track. To balance this cost, the maintenance costs have been quoted as reduced by 3 to 5 times that of ballasted track on a high-speed line in Japan. If low levels of use are foreseen, or if low capital cost is a more important requirement, ballasted track would be the choice. For a heavily used railway, particularly one in a structurally restricted area like a tunnel or viaduct, non-ballasted track must be the best option on grounds of low maintenance cost and reduced space requirements. However, care must be taken during design and installation to ensure the best out of the system. The earth mat is a steel mesh screen provided on electrified railways to try to keep stray return currents from connecting to utilities pipes and nearby steel structures. Earthing must be strictly controlled otherwise serious and expensive problems will occur, made more serious and expensive because they involve other people's property. Some slab track systems have the sleepers resting on rubber or similar pads so that they become "floating slab track". Floating track is used as a way of reducing vibration. Hong Kong Mass Transit Railway is fond of it, since its lines run through very densely populated areas. Following is a diagram of a modern slab track system showing the prefabricated track suspended in the tunnel (or viaduct structure) while concrete is poured around it.
Page 16 of 259
Figure 6: Slab Track System
1.3 Sleepers (Ties) In the early years of railways, there was much experimentation with rails and sleepers and fixtures, before the better designs emerged. Wooden rails with a metal strap on top was tried to save costs, but the straps had a tendency to come loose and penetrate the carriages going over them. Barlow rail had a wide cross section to spread the load, but the rail itself tended to spread and go out of gauge. Brunel's Great Western Railway used longitudinal sleepers, with piles to hold the track down, but as the earthworks settled, the piles came to hold the track up. A railroad tie, crosstie, or sleeper is a rectangular object used as a base for railroad tracks. Sleepers are members generally laid transverse to the rails and on which rails are supported and fixed to transfer the loads from rails to the ballast and sub grade below and to hold the rails to the correct gauge. Traditionally, ties have been made of wood but concrete is now widely used, though steel has been used and plastic has been tried. In the US most ties are made of oak soaked in creosote and last up to 20 years. Most Class 1 Railroads replace them after 5-10 years and then sell them. Concrete ties are popular in western US and on passenger lines in the east. Steel rails are secured on sleepers to keep them at the correct distance apart (the gauge) and capable of supporting the weight of trains. There are various types of sleepers and methods of securing the rails to them. Sleepers are normally spaced at 650 mm (25 ins) to 760 mm (30 ins) intervals, depending on the particular railway's requirement.
1.3.1
Wooden sleepers
Timber sleepers are usually of a variety of hardwoods, and are often heavily creosoted or, less often, treated with other preservatives. The problems with wood are the tendency to rot, particularly around the fastenings used to hold the rails to them. Traditionally, sleepers (known as cross-ties or simply ties in the US) are wooden. They can be softwood or hardwood. Most sleepers in the UK are softwood, although London Underground uses a hardwood called Jarrah wood. Sleepers normally impregnated with preservative will last up to 25 years under good conditions. They are easy to cut and drill, and used to be cheap and plentiful. Nowadays, they are becoming more expensive and other types of materials have appeared, notably concrete and steel.
Page 17 of 259
Figure 7: Wooden Sleepers
1.3.2
Concrete Sleepers
Figure 8: Concrete Sleepers
Concrete is the most popular of the new types of sleepers. Concrete sleepers are much heavier than wooden ones, so they resist movement better. They work well under most conditions but there are some railways, which have found that they do not perform well under the loads of heavy haul freight trains. They offer less flexibility and it has been alleged that they crack more easily under heavy loads with stiff ballast. They also have the disadvantage that they cannot be cut to size for turnouts and special track work. A concrete sleeper weighs up to 320 kg (700 lbs) compared with a wooden sleeper, which weighs about 100 kg or 225 lbs. The spacing of concrete sleepers is about 25% greater than that of wooden sleepers. Typical concrete sleepers are shown in the photo above.
Page 18 of 259
Concrete sleepers have become more common mainly due to their greater economy and better support of the track under heavy traffic. In the early period of history of railways, wood was the only material used for making sleepers in Europe. Even in those days, occasional shortages of wood and the increasing price of wood posed problems. This induced engineers to find an alternative to wooden sleepers. With the development of concrete technology in the 19th century, concrete had established its place as a versatile building material and could be adopted to meet the requirements of railway sleepers. In 1877 Joseph Monnier a French gardener and inventor of reinforced concrete suggested that cement concrete could be used for making sleepers for the railway track. Monnier in fact designed a sleeper and obtained a patent for it, but it did not work successfully. The designs were further developed and the railways of Austria and Italy produced the first concrete sleepers around the turn of the 20th century. Other European railways closely followed this. Much progress, however, could not be achieved till 2nd World War, when wooden sleepers practically disappeared from the markets and their prices greatly increased. Almost at the same time, as a result of extensive research carried out by the French railways and other European railways, the modern concrete sleeper was developed. Heavier rail sections and long welded rails were also being produced. This necessitated the need for a better type of sleeper, which could fit in the modern track. These conditions gave a spur to the development of concrete sleepers and countries such as France, Germany and Britain went in a big way for development of these concrete sleepers to perfection.
1.3.3
Plastic sleepers
Recently, composite ties have come on the market. They are made of something like old tires and recycled plastic. They can be used and spiked like regular ties, cost about 50% less and save on trees. A number of companies are selling railroad ties manufactured of recycled plastic materials. These ties are said to outlast the classical wooden tie, be practically impervious to the seasons, but otherwise exhibit the same properties as their wooden counterparts with respect to damping of impact loads, lateral stability, and sound absorption. These products have gained limited acceptance.
1.3.4
Twin-Block Sleepers
Another type of concrete sleeper as shown in the drawing below is the twin-block sleeper. The design consists of two cast concrete blocks held to gauge by a steel bar that is normally covered by ballast. It is popular in France and is also known by the names Sonneville block or Stedef block. A twin-block sleeper is lighter by 30% compared to a regular concrete sleeper thus allowing it to be manually moved and the four faces of the two blocks resist movement better. These are excellent for some lighter track forms like those used for tramway systems.
Figure 9: Twin Block Sleepers
The example in the Sheffield Supertram LRT below shows concrete twin block sleepers supplemented with wooden sleepers in the same track at the crossover, because it is easier to cut timber to the correct size. Sleepers at crossovers and turnouts vary in size according to their position in the layout. Steel sleepers are also now used on more lightly used railroads, but they are regarded as suitable only where speeds are 100 mi/h (160 km/h) or less.
Figure 10: Mixed concrete and wooden sleepers
Page 19 of 259
1.3.5
Other sleeper variants
Figure 11: Steel Sleepers
Figure 12: Iron & Brick Sleepers
Figure 13: Sleeper-less track for the high speed route Nürnberg–Ingolstadt
2
Design
Track design is a complex and multi-disciplinary engineering science involving earthworks, steelworks, timber and suspension systems. Many different systems exist throughout the world and there are many variations in their performance and maintenance.
2.1 Track Alignment The route upon which a train travels and the track is constructed is defined as an alignment. To give a train a good ride, the alignment must be set to within a millimetre of the design. An alignment is defined in two fashions. First, the horizontal alignment defines physically where the route or track goes (mathematically the XY plane). The second component is a vertical alignment, which defines the elevation, rise and fall (the Z component).
Page 20 of 259
Vertical alignment is the degree to which the track undulates in the vertical plane. Vertical alignment must be measured to predict interaction and possible resonance with rolling stock at certain speeds and with characteristic suspension/damping properties. Wavelengths greater than 200m may be ignored as being natural hills and valleys. Wavelengths under 1m are normally called corrugation. Wavelengths that pose particular problems are:
5 to 15m (Cyclic Top) - This presents a derailment danger to stiffly sprung freight. 40 to 100m - This will affect the passenger comfort of high speed trains.
Alignment considerations weigh more heavily on railway design versus highway design for several reasons:
First, unlike most other transportation modes, the operator of a train has no control over horizontal movements (i.e. steering). The guidance mechanism for railway vehicles is defined almost exclusively by track location and thus the track alignment. The operator only has direct control over longitudinal aspects of train movement over an alignment defined by the track, such as speed and forward/reverse direction. Secondly, the relative power available for locomotion relative to the mass to be moved is significantly less than for other forms of transportation, such as air or highway vehicles. Finally, the physical dimension of the vehicular unit (the train) is extremely long and thin, sometimes approaching two miles in length. This compares, for example, with a barge tow, which may encompass 2-3 full trains, but may only be 1200 feet in length.
These factors result in much more limited constraints to the designer when considering alignments of small terminal and yard facilities as well as new routes between distant locations. The designer MUST take into account the type of train traffic (freight, passenger, light rail, length, etc.), volume of traffic (number of vehicles per day, week, year, life cycle) and speed when establishing alignments. The design criteria for a new coal route across the prairie handling 15,000 ton coal trains a mile and a half long ten times per day will be significantly different than the extension of a light rail (trolley) line in downtown San Francisco.
Figure 14: Vertical Alignment
Figure 15: New Mexico: Rail Runner Route to Santa Fe
Page 21 of 259
Figure 16: New Mexico: Portion of the new alignment extending along the existing track east of I-25
Figure 17: New Mexico: Portion of the new alignment entering the I-25 median near the rest area
Page 22 of 259
Figure 18: New Mexico: The Santa Fe Southern alignment extending from I-25 to the Santa Fe Railyards
Page 23 of 259
2.1.1
Curves
Curves in the track are almost a science on their own. Careful calculations are required to ensure that curves are designed and maintained properly and that train speeds are allowed to reach a reasonable level without causing too much lateral stress on the track or inducing a derailment. There are both vertical curves and horizontal curves. There is also a section of track on either side of a curve known as the transition, where the track is changing from straight to a curve or from a curve of one radius to one of another radius.
2.1.1.1
Track Transition Curve
A Track transition curve, or spiral easement, is a mathematically calculated curve on a section of highway, or railroad track, where a straight section changes into a curve. It is designed to reduce the centripetal force needed to change the direction of the vehicle and the centrifugal force experienced by users. In plan (i.e., the horizontal curve) the start of the transition is at infinite radius and at the end of the transition it has the same radius as the curve itself, thus forming a very broad spiral. At the same time, in the vertical plane, the outside of the curve is gradually raised until the correct degree of bank is reached. If such easement were not applied the centripetal force would be applied instantly at one point: the tangent point where the straight track meets the curve, with undesirable results. With a road vehicle the driver naturally applies the steering alteration in a gradual manner and the curve is designed to permit this, using these principles.
History On early railroads, because of the low speeds and wide-radius curves employed, the surveyors were able to ignore any form of easement but in 1835 Charles Vignoles published an exact, although complex, equation for the vertical component. In 1837 the vertical and horizontal components were combined in William Froude’s curve of adjustment (a cubic parabola), based on the theoretical calculations of William Gravatt. In the UK, only from 1845 when legislation and land costs began to constrain the laying out of rail routes and tighter curves were necessary, did the principles start to be applied in practice
Figure 19: Parabolic transition curve as used with the Belgian Railways. This sign aside a railroad (between Ghent and Bruges) indicates the start of the transition curve. A parabolic curve (POB) is used.
Geometry While railroad track geometry is intrinsically three-dimensional, for practical purposes the vertical and horizontal components of track geometry are usually treated separately. The overall design pattern for the vertical geometry is typically a sequence of constant grade segments connected by vertical transition curves in which the local grade varies linearly with distance and in which the elevation therefore varies quadratically with distance. Here grade refers to the tangent of the angle of rise of the track. The design pattern for horizontal geometry is typically a sequence of straight line (i.e., a tangent) and curve (i.e. a circular arc) segments connected by transition curves. In a tangent segment the track bed roll angle is typically zero. In the case of railroad track the track roll angle (cant or camber) is typically expressed as the difference in elevation of the two rails, a quantity referred to as the superelevation. A track segment with constant non-zero curvature will typically be superelevated in order to have the component of gravity in the plane of the track provide a majority of the centripetal acceleration inherent in the motion of a vehicle along the curved path so that only a small part of that acceleration needs to be accomplished by lateral force applied to vehicles and passengers or lading. The change of superelevation from zero in a tangent segment to the value selected for the body of a following curve occurs over the length of a transition curve that connects the tangent and the curve proper. Over the length of the transition the curvature of the track will also vary from zero at the end abutting the tangent segment to the value of curvature of the curve body, which is numerically equal to one over the radius of the curve body. The simplest and most commonly used form of transition curve is that in which the superelevation and horizontal curvature both vary linearly with distance along the track. Cartesian coordinates of points along this spiral are given by the Fresnel sine and cosine integrals. The resulting shape matches a portion of a Cornu spiral and is also referred to as a clothoid. However, as it causes the horizontal (centripetal) acceleration to ramp up linearly from zero to the value associated with the circular motion in the body of the curve, in a transportation context it may best be referred to as the linear spiral.
Page 24 of 259
A transition curve can connect a track segment of constant non-zero curvature to another segment with constant curvature that is zero or non-zero of either sign. Successive curves in the same direction are sometimes called progressive curves and successive curves in opposite directions are called reverse curves. The linear spiral has two advantages. One is that it is easy for surveyors because the coordinates can be looked up in Fresnel integral tables. The other is that it provides the shortest transition subject to a given limit on the rate of change of the track superelevation (i.e. the twist of the track). However, as has been recognized for a long time, it has undesirable dynamic characteristics due to the large (conceptually infinite) roll acceleration and rate of change of centripetal acceleration at each end. Because of the capabilities of personal computers it is now practical to employ spirals that have dynamics better than those of the linear spiral.
2.1.1.2
Cant
Cant or superelevation are terms used to indicate the difference in elevation of the two edges of a curved track by raising of the outer rail or to allow faster speeds than if the two rails were level. Cant compensates for the centrifugal force arising from a train traversing a curve. It is the desired and designed inclination of the track and is calculated from track curvature, speed limits, axle weights etc.
Figure 20: Effects of Centrifugal Force
Figure 21: Overbalanced, Equilibrium and Under-balanced
Page 25 of 259
Figure 22: Cant or Superelevation
Figure 23: Cant or Superelevation
In the USA maximum track speed is subject to specific regulatory restrictions known as rules. For example, the rules restrict speeds within recognized rail yards to 10 mph. The rule governing the maximum permissible speed of a train operating on curved track is determined by the following formula:
where, Ea is the amount in inches that the outside rail is super-elevated above the inside rail on a curve and d is the degree of curvature in degrees per 100 feet. Vmax is given in miles per hour. Track super-elevation in the U.S. is restricted to 3 inches, though 4 inches is permissible by waiver. There is no hard maximum set for European railways, some of which have curves with over 11 inches of super-elevation to permit high-speed transportation.
Figure 24: Cant
Page 26 of 259
A cant which is not equal to zero results in a banked turn, allowing vehicles travelling through the turn to go at higher speeds than would normally be possible. It is the name used to describe the cross level angle of track on a curve, which is used to compensate for lateral forces generated by the train as it passes through the curve. In effect, the sleepers are laid at an angle so that the outer rail on the curve is at a higher level than the inner rail. The cant helps a train steer around a curve keeping the inside wheel edges i.e. the wheel flanges from touching the rails, minimizing friction and wear. Of course, there will usually be trains of different types with permitted speeds at different levels that travel the same curve. In addition, there will be occasions when trains stop on the curve. The amount of cant has to be chosen for a given speed, so if trains travel through the turn at different speeds the cant will cease to serve its purpose and will actually lead to damage to the wheels when going both above and below the original design speed. Hence, a compromise value of cant must be chosen when turns are designed to allow the safety of stopped trains and the best speeds for all trains moving on the curve. Cant is measured either in degrees or in linear dimensions. On standard gauge track (1435 mm or 4ft. 8½ins.) 150 mm or 6 ins. of cant is equal to 6 degrees. This is the normal maximum in the UK. Ideally, the track should have railroad ties (sleepers) at an increased rate per mile i.e. at closer spacing, and a greater depth of ballast to accommodate the increased forces exerted by the moving train. At the ends of a curve, the amount of cant cannot change from zero to its maximum immediately. Rather, the cant must change (ramp) gradually in a track transition curve. The length of the transition curve depends on the maximum speed on the line. The higher the speed, the greater is the length that is required. The main functions of cant are:
To better distribute the load across both rails To reduce the wear of rails and rolling stock To neutralize the effect of lateral forces To provide comfort to passengers
In Australia, ARTC is increasing speed around curves sharper than 800 m radius by replacing wooden sleepers with heavier, concrete ones so that the cant can be increased.
Degree of Curvature This describes an American practice that was a great convenience to the transitman.
Figure 25: Circular Curve
A circular curve is often specified by its radius. A small circle is easily laid out by using the radius. In a mathematical sense, the curvature is the reciprocal of the radius, so that a smaller curvature implies a large radius. A curve of large radius, as for a railway, cannot be laid out by using the radius directly. We will see how the problem of laying out a curve of large radius is solved. In American railway practice, the radius is not normally used for specifying a curve. Instead, a number called the degree of curvature is used. This is indeed a curvature, since a larger value means a smaller radius. The reason for this choice is to facilitate the computations necessary to lay out a curve with surveying instruments, a transit and a 100-ft engineer's tape. It is more convenient to choose round values of the degree of curvature, rather than round values for the radius, for then the transit settings can often be calculated mentally. A curve begins at the P.C., or point of curvature, and extends to the P.T., or point of tangency. The important quantities in a circular curve are illustrated above. The degree of curvature is customarily defined in the United States as the central angle D subtended by a chord of 100 feet. The reason for the choice of the chord rather than the actual length of circumference is that the chord can be measured easily and directly simply by stretching the tape between its ends. A railway is laid out in lengths called stations of one tape length, or 100 feet. This continues through curves, so that the length is always the length of a series of straight lines that can be directly measured. The difference between this length, and the actual length following the curves, is inconsequential, while the use of the polygonal length simplifies the calculations and measurements greatly.
Figure 26: Definition of Degree of Curve D
Page 27 of 259
The relation between the central angle d and the length c of a chord is simply R sin(d/2) = c/2, or R = c/(2 sin d/2). When c = 100, this becomes R = 50/sin D/2, where D is the degree of curvature. Since sin D/2 is approximately D/2, when D is expressed in radians, we have approximately that R = 5729.65/D, or R = 5730/D. Accurate values of R should be calculated using the sine. For example, a 2° curve has R = 2864.93 (accurate), while 5730/D = 2865 ft. If some other value and length unit are chosen, simply replace 100 by the new value. In the metric system, 20 meters is generally used as the station interval instead of 100 ft, though stations are numbered as multiples of 10 m, and these equations are modified accordingly. With a 20 m chord, R = 1146/D m,or about 3760/D ft. Of course, a given curve has different degrees of curvature in the two systems. There are several methods of defining degree of curvature for metric curves. D may be the central angle for a chord of 10 m instead of 20 m. The deflection from the tangent for a chord of length c is half the central angle, or δ = d/2. This is a general rule, so additional 100 ft chords just increase the deflection angle by D/2. Therefore, it is very easy to find the deflection angles if a round value is chosen for D, and usually easy to set them off on the instrument. For example, if a curve begins at station 20+34.0 and ends at station 28+77.3, the first subchord is 100 - 34.0 = 66.0 ft to station 21, then 7 100 ft chords, and finally a subchord of 77.3 ft. The deflection angle from the P.C. to the P.T. for a 2° curve is 0.660 + 7 x 1.0 + 0.773 = 8.433 °, or 8° 26'. I have used the approximate relation δ = (c/100)(D/2) to find the deflection angles for the subchords. The long chord C from P.C. to P.T. is a valuable check, easily determined with modern distance-measuring equipment. It is C = 2R sin (I/2), where I the total central angle. For the example, C = 2(2864.93)sin(8.433) = 840.32 ft. The length of the curve, by stations, is 843.30 ft. This figure can be checked by actual measurements in the field. The actual arc length of the curve is (2864.93)(0.29437) = 843.34 ft. Note that this is the arc length on the centre line; for the rails, use R ± g/2, where g = 4.7083 ft = 56.5 in = 1435 mm for standard gauge. Before electronic calculators, small-angle approximations and tables of logarithms were used to carry out the computations for curves. Now, things are much easier, and I write the equations in a form suitable for scientific pocket calculators, instead of using the traditional forms that use tabular values and approximations. A 1° curve has a radius of 5729.65 feet. Curves of 1° or 2° are found on high-speed lines. A 6° curve, about the sharpest that would be generally found on a main line, has a radius of 955.37 feet. On early American railroads, some curves were as sharp as 400 ft radius, or 14.4°. Street railways have even sharper curves. The sharpest curve that can be negotiated by normal diesel locomotives is not less than 250 ft radius, or 23°. It is not difficult to apply spirals, in which the change of curvature is proportional to distance, to the ends of a circular curve. Circular curves are a good first approximation to an alignment. The centrifugal acceleration in a curve of radius R negotiated at speed v is a = v2/R. If v is in mph, a = 2.1511v2/R = 3.754 x 10-4Dv2 ft/s2, where D is degrees of curvature. This is normal to the gravitational acceleration of 32.16 ft/s2, and the total acceleration is the vector sum of these. For comfort, a maximum ratio of a to g may be taken as 0.1 (tan-1 5.71°). The overturning speed depends on the height of the centre of gravity, and occurs when a line drawn from the centre of gravity parallel to the resultant acceleration passes through one rail. The height of the centre of gravity of American railway equipment is 10 ft or less. Taking 10 ft as the height of the centre of gravity, a/g = 0.2354 (tan-1 13/25°). Therefore, the overturning speed vo can be estimated by Dvo2 = 20,000 and the comfort speed vc by Dvc2 = 8500. A curve may be superelevated by an amount s so that the resultant acceleration is more normal to the track. Exact compensation occurs only for one speed, of course. This angle of bank is given by tan θ = a/g = 1.167 x 10-5Dv2, and sin θ = s/gauge. Consider a 2° curve. For v = 60 mph, tan θ = 0.08404, sin θ = 0.08375 and s = 4.73 in. If the speed is greater than this, there will be an unbalanced acceleration, which will have a ratio of a/g of 0.1 at a speed v' given by 0.1 = 1.167 x 10-5D(v'2 - v2), or v' = 89 mph. The overturning speed on this curve is given by (0.2354 + 0.08404) = (1.167 x10-5)Dv2, or v = 117 mph. Note that a large superelevation will cause the flanges of a slow-moving train to grind the lower rail. Superelevation is generally limited to 6 to 8 in maximum.
Cant deficiency In practice, faster trains are allowed to travel round the curve at a speed greater than the equilibrium level offered by the cant setting. Passengers will therefore feel a lateral acceleration similar to what they would feel when there were no cant and the train were travelling at a lower speed round the curve. The difference between the equilibrium cant required by the higher speed and the actual cant is known as the cant deficiency. The maximum amount of cant deficiency allowed is 110 mm (4½ ins.). After a period of use, subsidence may lead to a super-elevation that is deficient in cant. This shortfall is equivalent to cross-level or cant deficiency. The difference between the equilibrium cant required by the higher speed, i.e. the desired cant and the actual cant is known as the cant deficiency or cross level or level transfer. It is the difference between the actual super-elevation and the desired cant. In both the examples below the right hand rail is low on cross level:
Figure 27: Cant Deficiency
Page 28 of 259
The term "cant deficiency" is defined in the context of travel of a rail vehicle at constant speed on a constant radius curve. Cant itself is a British synonym for the superelevation of the curve, that is, the elevation of the outside rail minus the elevation of the inside rail. Cant deficiency is present when a vehicle's speed on a curve is greater than the speed at which the components of wheel to rail force normal to the plane of the track would be the same in aggregate for the outside rails as for the inside rails. The forces that bear on the vehicle in this context are illustrated in the following figure:
Figure 28: Forces bearing on a vehicle
A vehicle's motion at speed v along a circular path embodies centripetal acceleration of magnitude v^2 / R toward the centre of the circle, the curvature of that path being 1 / R where R is the radius of the circle. This centripetal acceleration is produced by horizontal forces applied by the rails to the wheels of the vehicle, directed toward the centre, and having sum equal to M * v^2 / R where M is the mass of the vehicle. The net horizontal force producing the centripetal acceleration is generally separated into components that are respectively in the plane of the superelevated (i.e., banked) track and normal thereto. The component normal to the track acts together with the much larger component of gravitational force normal to the track and is generally neglected. It can slightly increase the vertical load seen by the vehicle suspension but it does not create lateral acceleration as perceived by passengers or and does not cause lateral deflection of the vehicle suspension. The track is superelevated so that the component of the acceleration of gravity in the plane of the track will provide some fraction of the horizontal acceleration in the plane of the track due to the circular motion. Referring to the figure above, it can be seen that the components of gravitational and centripetal acceleration in the plane of the track will be equal when the balance equation, (V2 / R) cos(bank_angle) = g x sin(bank_angle), is satisfied. For a given curve radius and bank angle (i.e., superelevation) the speed V that satisfies the balance equation is called the balancing speed and is given by Vbal =
( R x g x tan(bank_angle))1/2.
For reasons that will be mentioned below, passenger vehicles usually traverse a curve at a speed higher than the balance speed. The amount by which the actual speed exceeds the balance speed is conveniently expressed via the so-called cant deficiency, i.e., by the amount by which the superelevation would need to be increased to raise the balance speed to the speed at which the vehicles actually travel. Letting gauge_se denote the rail gauge from low rail gauge side corner to high rail field side corner, letting super_el denote the actual superelevation, and letting Vact denote the actual speed, it follows from the definition that the cant deficiency, CD, is given by the formula CD = gauge_se / ( 1 + R2 x g2 / Vact4)1/2 - super_el. Taking an example, a curve with curvature 1.0 degree per 100 ft chord (radius 5,729.65 ft = 1,746.40 m), gauge_se = 59.5 inches (1511.3 mm), and superelevation 6.0 inches (152.4 mm) will have Vbal =
(1746.4 x 9.80665 x tan(asin(152.4 /1511.3)))1/2
= 41.6638 meters/s = 149.99 km/h = 93.20 miles/h. If a vehicle traverses that curve at a speed of 125 mph = 201.17 km/h = 55.880 meters/s, then the cant deficiency will be CD = 4.67 inches = 118.7 mm. On routes that carry freight traffic in cars with the maximum allowed axle loads it will be desirable to set superelevations so that the balancing speed of each curve is close to the speed at which most such traffic runs. This is to lessen the tendency of heavy wheel loads to crush the head of either rail.
Page 29 of 259
For passenger traffic superelevations and authorized speeds can be set so that trains run with as much cant deficiency as is allowed based on safety, on relevant regulations, and on passenger comfort. As of 2007 the FRA regulations limit CD to 7.0 inches for tilting passenger vehicles, but work is underway to see if this limit can be safely increased to 9.0 inches. (In England, where axle loads are typically lower than those in the USA, tilting trains are allowed to operate with 12.0 inches CD in some cases. Russia, as an example, could allow greater CD in light of its wider track gauge.) Allowed CD could be set below the value that would be allowed based on safety in order to reduce wheel and rail wear and to reduce the rate of degradation of geometry of ballasted track. Choice of design CD will be less constrained by passenger comfort in the case of vehicles that have socalled tilting capability. One historical approach to determining safe cant deficiency was the requirement that the projection to the plane of the track of the resultant of the centrifugal and gravitational forces acting on a vehicle fall within the middle third of the track gauge. Contemporary engineering studies would likely use vehicle motion simulation including cross wind conditions to determine margins relative to derailment and rollover. If the superelevation determined for a dedicated passenger route curve on regulatory and safety bases is below 6.0 inches (152.4 mm) it may be desirable to increase the superelevation and reduced the cant deficiency. However, if on such a curve some trains regularly travel at low speeds, then raising the superelevation may be inadvisable for passenger comfort reasons. On a mixed traffic route owned by a freight rail company, freight considerations are likely to prevail. On a mixed traffic route owned by a passenger rail company some kind of compromise may be needed. Cant deficiency is generally looked at with respect to ideal track geometry. As geometry of real track is never perfect it may be desirable to supplement the static considerations laid out above with simulations of vehicle motion over measured geometries of actual tracks. Simulations are also desirable for understanding vehicle behaviour traversing spirals, turnouts, and other track segments where curvature changes with distance by design. Where simulations or measurements show non-ideal behaviour traversing traditional linear spirals, results can be improved by using advanced spirals. Good track geometry including advanced spirals is likely to foster passenger acceptance of higher CD values.
2.1.1.3
Side Wear
Due to the centrifugal force of traffic in a curve, the side of a rail will become worn down. The measurement of side wear is given as the reduction in width of the rail from the nominal new rail size. This is measured at a specific point below the rail head (P-point).
Figure 29: Rail head side wear
2.1.1.4
Twist
Twist is the rate of change of super-elevation. A degree of twist must occur during the transition between tangential and curved track. Twist becomes a danger if it exceeds the suspension travel in a bogie, i.e. a wheel will lift free. Hence twist is usually measured over the wheelbase of the most common rolling stock bogie.
Figure 30: Twist
2.1.1.5
Warp
Warp, not to be confused with twist, is the greatest difference in super-elevation anywhere within a given length. It is usually measured over the rolling stock wheelbase or centres of bogies.
Figure 31: Warp
Page 30 of 259
2.2 Structure Gauge and Kinematic Envelope To ensure that the path required for the passage of trains is kept clear along the route of a railway, a "structure gauge" is imposed. This has the effect of forming a limit of building inside which no structures may intrude. The limit includes not only things like walls, bridges and columns but also pipes, cables, brackets and signal posts. The structure gauge will vary with curvature of the line and maximum speeds allowed along the section in question. Just as the civil engineer is prevented from allowing his structure to intrude into the train path, the rolling stock engineer also has limits imposed on the space his train may occupy. This space is referred to as the "kinematic envelope". The area designates the limits within which the train can move laterally and vertically along the route. Speed and features of train design such as bogie suspension and special systems such as tilting that it may have will affect the kinematic envelope. The line route has to be checked from time to time to ensure that the structures are not interfering with the gauge. A line is always gauged when a new type of rolling stock is to be introduced. It is important to see that small variations in track position, platform edge, cable duct location and signal equipment haven’t been allowed to creep inwards during maintenance and renewal programmes. Gauging used to be done by hand locally (and still is from time to time in special circumstances) but nowadays it is mostly done with a special train. The train used consist of a special car with a wooden frame built almost to the gauge limits. The edges of the frame were fitted with lead fingers so that, if they hit anything as the train moved along, they would bend to indicate the location and depth of intrusion. Modern gauging trains are fitted with optical or laser equipment. The optical system uses lights to spread beams of light out from the train as it runs along the line. Suitably mounted cameras record breaks in the light beams to provide the gauging information. The train can run at up to 50 mi/h (80 km/h) but, of course, the runs have to be done at night. Laser beams are also used but, as they rotate round the train and form a "spiral" of light, the method suffers from gaps that can allow intrusions to be missed.
2.3 Monuments and Datum Plates Along the line of route, various locations are marked by a fixed post in the track or a plate on a nearby structure to indicate the correct level or position of the track. These are called monuments or datum plates. Measurements are taken from these to confirm the correct position of the track.
2.4 U.S. track classes In the United States, the Federal Railroad Administration has developed a system of classification for track quality. The class a track is placed in determines speed limits and the ability to run passenger trains. The lowest class is referred to as excepted track. Only freight trains are allowed to operate on this type of trackage and they may run at speeds up to 10 mph (16 km/h). Also, no more than five cars loaded with hazardous material may be operated within any single train. Passenger trains of any kind are prohibited, including chartered excursions or fan-trips.
Class 1 track is the lowest class allowing the operation of passenger trains. Freight train speeds are still limited to 10 mph (16 km/h, and passenger trains are restricted to 15 mph (24 km/h). Class 2 track limits freight trains to 25 mph (40 km/h) and passenger trains to 30 mph (48 km/h). Class 3 track limits freight trains to 40 mph (64 km/h) and passenger trains to 60 mph (96 km/h). There is currently a legal battle between Amtrak and the Guilford Rail System over its trackage from Haverhill, MA, to Portland, ME. Amtrak is fighting for the Class 3 trackage to be used to operate its Down-easter at 79 mph (126 km/h). Class 4 track limits freight trains to 60 mph (96 km/h) and passenger trains to 80 mph (128 km/h). Most track especially that owned by major railroads the Union Pacific, BNSF, CSX, and Norfolk Southern is class 4 track. Due to a technicality in law, Amtrak trains are limited to 79 mph (126 km/h) on this track, unless cab signalling or automatic train stop are employed. Class 5 track limits freight trains to 80 mph (128 km/h) and passenger trains to 90 mph (144 km/h). The most significant portion of Class 5 track is part of the Burlington Northern Santa Fe's Chicago–Los Angeles mainline, the old Santa Fe main, upon which Amtrak's Southwest Chief can operate at up to 90 mph (144 km/h). This is notable as the only area outside Amtrak-owned trackage or trackage upgraded through state funds where Amtrak trains can operate above 79 mph (126 km/h). Class 6 limits freight trains and passenger trains to 110 mph (176 km/h). Amtrak is currently working with the Iowa Interstate Railroad and the state of Illinois to upgrade a portion of its Chicago, Illinois–Kansas City, Missouri line to Class 6. Class 7 limits all trains to 125 mph (200 km/h). Most of Amtrak's Northeast Corridor is Class 7 trackage. Class 8 limits all trains to 160 mph (256 km/h). A few small lengths of the Northeast Corridor are the only Class 8 trackage in North America. Class 9 trackage limits all trains to 200 mph (320 km/h). There is currently no Class 9 trackage.
2.5 Route Selection 2.5.1
Route Optimising Criteria
Hardened steel wheels on hardened steel rails have very low rolling resistance. With low rail rolling resistance combined with low-friction wheel bearings it becomes possible to move relatively large masses with low motive power provided that grade or slope and other resistances are minimized. Relatively low-speed long close-coupled trains have relatively low air resistance in the direction of travel. The success of a rail system depends on managing the extra resistances or accelerations resulting from the slopes of the route. A powered wheeled vehicle generally has to
Page 31 of 259
overcome acceleration, rolling, slope and air resistance. The motive power that can be utilized depends on the number and characteristics of the drive wheels. Railway trains tend to have relatively low power to mass ratios compared with road vehicles. The criteria for railway main line route location are standardized for the class of rail service. The American Railway Engineering Manufacturers Association (AREMA) has been the major standardising agency in America. Each major rail organization has it's own versions of these standards. Some representative values are shown below: a. b. c.
d.
Maximum grades up and down, i.e. slopes of ideally less than 0.005 (0.5percent), but below 0.015 (1.5percent). Curve radius so that side acceleration is low (preferably approaching zero) on super elevated curves with cross slope of 0.06 or less. Curves translate into a form of slope resistance, so it is desirable to have changes in direction at low slope locations. Design speeds up to 200 km/h for passenger trains and 140 km/h for freight trains. Generally freight trains are more concerned with moving mass with infrequent stops. Passenger trains require speed to reduce travel time and more rapid acceleration and braking to minimize productivity loss due to stops. Local service passenger trains such as those used in urbanized areas have frequent stops so that they are usually accelerating or decelerating. Favourable adjacent terrain free from slides, major stream crossings, adjacent land improvements, and grade crossings with other modes.
2.5.2 2.5.2.1
System Design as a Function of Train Performance, Train Resistance Choosing best route for a freight line
Figure 32: System design as a function of train performance, train resistance
Page 32 of 259
In the picture below, a freight train laden with coal could have three ways to reach point H. One objective might be to minimize the total energy used (HP-hours) while another might be to minimize travel time.
Figure 33: Three Ways to ‘H’ With Coal
Train Resistance comprises two forces of resistance, (a) inherent or level tangent resistance and (b) incidental resistance (a) Inherent or level tangent resistance = ƒ(speed, cross-sectional area, axle load, journal type, winds, temperature, and track condition). Using a Davis equation variation (from Hay, pg. 76),
where:
Ru = unit resistance in pounds per ton of train weight w = weight per axle in tones - weight on rails in tons (W) divided by the number of axles (n) b = an experimental coefficient based on flange friction, shock, sway, and concussion A = cross-sectional area in square feet of the car or locomotive C = drag coefficient based on the shape of the front end of the car or locomotive and the overall configuration, including turbulence from car trucks, air-brake fittings under the cars, space between cars, skin friction and eddy currents, and the turbulence and partial vacuum at the rear end
(b) Incidental resistance = f (curvature, grades)
Page 33 of 259
For a 100 car container train, 200,000 lbs/per car, 50 mph, 0.5% grade, 4° curve:
weight of locomotives = 300 tons/each weight of train = 100x200,000 lbs. = 20,000,000 lbs = 10,000 tons weight of single freight car (in tons) = 200,000/2,000 = 100 tons/car inherent force = 50,850 lbs. (about 5.1 lbs. per ton) w = 100 tons/4 axles = 25 tons/axle b = 0.03 for locomotives and 0.045 for freight cars (let’s use 0.045) A = 85 - 90 sq. ft. for freight cars (let’s use 90) C = 0.0017 for locomotives and 0.0005 for freight cars (let’s use 0.0005)
Inherent force = 1.3 + (29/25) + (0.03*50) + [(0.0005*90*502)/(25*4)] = 1.3 + 1.16 + 1.5 + (112.5/100) = 5.085 lbs/ton for the freight car = 5.085 lbs/ton * 10,000 tons = 50,850 lbs
Figure 34: How Much Energy It Takes to Move a Car
Page 34 of 259
Figure 35: Train Resistance
Figure 36: Energy needed to maintain speed, accelerate and curve
Page 35 of 259
2.5.2.2
Grade Resistance
Figure 37: Derivation of Grade Resistance
F = (W X CB) / AB = 20 lbs/ton for each percent of grade –
For our example: –
2.5.2.3
where: W = weight of car CB = distance between C and B AB = distance between A and B
Grade Resistance = 20 * 0.5 = 10 lbs/ton = 10 lbs/ton * 10,000 tons = 100,000 lbs
Curve Resistance:
Slippage of wheels along curved track contributes to curve resistance. See the following figures to visualize curve resistance.
Figure 38: Rolling cylinder concept
Page 36 of 259
Figure 39: Position of new wheel on new rail
Figure 40: Possible car/truck attitudes to rail and lateral forces
Page 37 of 259
Figure 41: Lateral slippage across rail head
Unit curve resistance values are determined by test and experiment. Conservative values are suitable for a wide range of conditions: 0.8 - 1.0 lbs/ton/degree of curve. Equivalent grade resistance:- divide curve resistance by unit grade resistance. For our example:
Equivalent grade resistance = 0.8/20 = 0.04 of the resistance offered by a 1% grade Curve resistance = (4 * 0.04) * 20 = 3.2 lbs/ton ; 3.2 lbs/ton * 10,000 tons = 32,000 lbs
THUS:
2.5.2.4
Total Resistance = 50,850 lbs + 100,000 lbs + 32,000 lbs = 182,850 lbs (or 18.3 lbs/ton), Car Resistance = 182,850 lbs/100 cars = 1829 lbs/car, and 182,850 lbs/80,000 lbs = 2.29 => 3 locomotives (assuming 80,000 lbs of pull/locomotive) would be needed to pull the train.
Choosing the Preferred Route
From Figure 33, resistance calculations would be done for each route and compared, as below:
Figure 42: Comparing the Energy It Takes to Deliver the Goods
Page 38 of 259
2.6 Tools Steps in design of permanent way may include sophisticated software programs for rail based infrastructure projects covering aspects from feasibility studies to detailed design, with user-friendly and easy to learn user interfaces. Combining powerful geometry and modelling tools with the knowledge of railway design, highly efficient and user-friendly design concepts have been developed over the years. There are professional tools available for high and normal speed railway lines, metro, light rail and also tramway design, that provide an advantage of combining and sharing data between civil engineering fields, such as having crossing roads, bridges, stations and parking areas in the same model, combined with noise calculation and visualisation of the entire system. Two well known tools are described in the following sections.
2.6.1
Bentley Rail Track
Following system activities may be covered under permanent way design:
Track design solution for railways Existing track analysis Regression analysis Alignments Turnouts Ballast, formation and earthworks Manufacturing details
Figure 43: Permanent way design flowchart
Page 39 of 259
2.6.1.1
Track Design Solutions for Railways
Scope of Bentley solutions includes:
Light and heavy rail International standards Configurable for design standards Configurable for drawing presentation Configurable for report formats Task and workflow driven
Tools available from Bentley include those for:
Survey Evaluation Modeller o Modelling Requirements Utilizes cant Utilizes cant rotation point (i.e. inside low rail) Enabling sub-grade widening (i.e. high side ballast) o Separate quantities for sub-ballast and ballast as well as the typical excavation / embankment o Ballast and earthworks
Figure 44: Ballasted Section Template
Page 40 of 259
o o o o
User defined templates Parametric and rules Creates feature lines in 3D Calculates layer volumes
Figure 45: Railway Model
Figure 46: Creating tunnels
Page 41 of 259
Figure 47: Visualisation
Figure 48: Driver’s Eye View
Drafting Surface analysis o Load survey data Survey Data Sources such as EDM, Aerial, Trolley, GPS Cloud scanning tools such as Cloudworx Data Import Tools such as: LandXML o Geometry and surface models Vendor Specific o Trimble Upload Add In Geometry and surface models
Page 42 of 259
Lieca Upload Add In Geometry and surface models o Display and view surfaces as contours, triangles, feature lines o Shade according to aspects, elevations and slopes o Triangulate surfaces o Design and edit surfaces Geometry design o Display Geometry Horizontal alignments Vertical alignments Elements in different styles Text and annotation Chainage Curve annotation Rails as 3D model elements Switch height plan o Regression analysis o Design by IP and Element methods, concurrently o Design Cant, integrated with horizontal alignment process o Place turnouts and diamonds o Co-ordinate geometry analysis o Design checking tools o
2.6.1.2
Existing Track Analysis Join rails – order points
Figure 49: Horizontal Regression Points
Convert rails to centreline from survey rails o Horizontal alignment o Cant alignment o Vertical alignment Validate regression data Display curvature and cant diagram Select points for analysis
Figure 50: Existing Track Analysis – Display Curvature Cant Diagram and select points for analysis
Page 43 of 259
2.6.1.3
Regression Analysis Single element analysis Dynamic regression analysis Dynamic display of slew o Straight – start and end o Curve – start, mid-point and end Single Element Regression Enhancement
Figure 51: Single Element Regression Analysis
2.6.1.4
Multi-element regression Horizontal and Vertical Least squares methodology Creates alignment elements o Straights o Transitions o Curves Check design quality Display design curvature diagram Display slew diagram o Horizontal o Vertical
Horizontal Alignment Design Design by curve set
Page 44 of 259
Figure 52: Design by Curve Set
Design by elements o Fixed o Float o Free o Straights, Transitions, Curves
Figure 53: Design by Elements
2.6.1.5
Turnouts Turnouts based on axis geometry for flexing
Figure 54: Turnout Schematic
Turnout Library
User definable libraries o Single branch o Double branch o Single slip o Double slip o Diamond crossing
Page 45 of 259
Figure 55: Turnout Library
2.6.1.6
Switches and Crossings Switch and Crossings based on rail geometry and lead rail distance and offset for flexing Switches and Crossings behave like turnouts in the system A Connection Editor joins switch and crossing and turnouts using plain line elements and resolves multi-element solutions A Cant Alignment Editor does automatic analysis of cant by design speed, uses editable values and allows virtual transitions
Figure 56: Switch and Crossing behaving like turnout
Figure 57: Switch and Crossing Library
Page 46 of 259
2.6.1.7
Vertical Design Design by curve set or elements Curves defined as parabolic or circular
Figure 58: Vertical Design - Curves
Review vertical alignment and slews Check design Carry out Profile Annotation o Includes existing from regression points o Includes horizontal slews o Includes vertical slews (lifts & lowers) o Includes rail elevations Tools for fabrication and construction detailing
Figure 59: Tools for fabrication and construction detailing
Modeller o o o o o
Ballast and earthworks User defined templates Parametric and rules Creates feature lines in 3D Calculates layer volumes
Page 47 of 259
A typical flowchart of railway track design is given below:
2.6.2
Novapoint Railway
Tools may include:
Advanced 3D railway alignment design Switch and Platform edge design tools Flexible and open user-specification of cross-sections tools for rehabilitation and optimisation of existing tracks Drawing presentation with customised layouts Data communication between a wide range of data sources Visualisation made easy with integrated and user-friendly 3D tools
Figure 60: Software tools for track design
Some aspects of Novapoint software-based railway design are explained below:
2.6.2.1
Creating the Geometry Horizontal and vertical alignment design is using cant (superstructure), element speed and element length as input parameters. Parameters for insufficient cant (I), ramp gradient (dh/l), variation of insufficient cant (dI/dt), and ramp gradient speed (dh/dt) are used as design guidelines. Horizontal transitions use clothoids; vertical curves can be defined with circular and parabolic curves, and k-values.
Figure 61: Alignment design
Page 48 of 259
Switch design is a tool for horizontal alignment design of selected standard or user-defined switches.
Figure 62: Switch design
Platform edge design calculates and presents the edge of platforms. This tool considers curves, with or without cant, transitions and switches in the platform area. Alignment design from surveyed data is a powerful tool for optimisation and rehabilitation of existing tracks based on surveyed rails or rail centre lines.
Figure 63: Alignment design from surveyed data
2.6.2.2
Modelling the project Track data identifies reference track settings in the cross-section, including cant values and design speed descriptions. Standard Cross-section Wizard simplifies the specification of the typical cross-sections, with predefined or user-defined rails, sleepers, ballast and substructure details.
Figure 64: Cross-section design
Railway Design is a flexible and advanced tool for detailed cross-section modelling. All substructure elements, ditch and drainage elements, side-areas and terrain adjustments can be optimised here. Using the in-built 3D-presentation and cross-section viewer makes it easy to optimise your project. Tools for quantity calculations, reports and setting out data to a number of formats (e.g. LandXML, Leica and Trimple) are also included.
Page 49 of 259
Figure 65: Sub-structure and terrain design
2.6.2.3 2.6.2.4
Analysing the project Vertical information along an alignment makes it easy to read information from connecting tracks. Distance between two alignments controls and verifies the track distances.
Presenting the project Novapoint Railway includes a number of tools to make the presentation and production of drawings more efficient. Plan drawing details as alignments, railway model, elevations, railway drawing symbols or frames. Longitudinal and cross-section drawings with a number of styles. Quantity/Mass haul diagrams.
Figure 66: Presenting
2.6.2.5
Setting out reports for export of selected data to all common formats, as alignment reports, switch data, cross-section data from the railway model and also tamping data. Novapoint can import and export data to a number of international formats, which makes communication with other tools easy.
Visualising the project A 3D visualisation of your project is just one click away. Presentation of the complete railway project, including roads, bridges, tunnels and station areas will improve the common understanding of complex projects. Paper drawings will never have the same appeal after introducing 3D models in the working process.
Figure 67: Visualisation
Page 50 of 259
3
Rail Profile
A Rail profile is a hot rolled steel profile of a specific shape or cross section (an asymmetrical I-beam). Unlike some other uses of iron and steel, railway rails are subject to very high stresses and have to be made of very high quality steel. It took many decades to improve the quality of the materials, including the change from iron to steel. Minor flaws in the steel that pose no problems in reinforcing rods for buildings, can, however, lead to broken rails and dangerous derailments when used on railway tracks. By and large the heavier the rails and the rest of the trackwork the heavier and faster the trains these tracks can carry. The rails represent a substantial fraction of the cost of a railway line. Only a small number of rail sizes are made by the steelworks at the one time, so a railway must choose the nearest suitable size. Worn, heavy rail from a mainline is often cascaded down to branch line, siding or yard use.
3.1 History Early rails were used on horse drawn wagon-ways. In the early days the rails were flanged (i.e. 'L' shaped) with the wagon wheels being flat. Over time it was realised that flanged wheels with flat rails worked better. These were sometimes strap-iron rails consisting of thin strips of iron strapped onto wooden rails. These rails were too fragile to carry heavy loads, but because the initial construction cost was less, this method was sometimes used to quickly build an inexpensive rail line. Strap rails sometimes separated from the wooden base and speared into the floor of the carriages above, creating what was referred to as a "snake head." However, the long-term expense involved in frequent maintenance outweighed any savings. The earliest in general use were the so-called cast iron "fish belly" rails from their shape. In time it became possible to roll longer lengths in wrought iron. The cross-sections varied widely from one line to another, but were of three basic types as shown in the diagram. The parallel cross-section, which developed in later years, was referred to as Bullhead. In May 1831, the first flanged T rail (also called T-section) arrived in America from Britain and was laid into the Pennsylvania Railroad by Camden and Amboy Railroad. Early fish belly metal rails made from cast iron were brittle and broke easily. They could only be made in short lengths that would soon become uneven. By 1840, wrought iron in longer lengths replaced cast iron as rolling techniques improved. The first steel rails were made in 1857 by Robert Forester Mushet, who laid them at Derby station in England. Steel was a much stronger material, which steadily replaced iron for use on railway rail and allowed much longer lengths of rails to be rolled. The use of welded rather than jointed track began in around the 1940s and had become widespread by the 1960s.
3.2 Tramway track
Figure 68: Light rail tracks with concrete railroad ties (sleepers).
Figure 69: Shape of Tram Rail
Tramway track is used on tramways or light rail operations, which, together with points guide trams, streetcars or light rail vehicles without the need for steering. Grooved rails (or girder rails) are often used in order to make street running feasible. Like standard rail tracks, tram tracks consist of two parallel steel rails. Tram rails can be placed in several surfaces. For example, they can be laid with standard rails on sleepers like railway tracks, or with grooved rails on concrete sleepers into street surfaces (pavement) for street running. Another environmentally friendly or ecologically friendly alternative is to lay tracks into grass turf surfaces; this is known as grassed track (or track in a lawn), first invented in Liverpool in 1924.
Page 51 of 259
The first tramways were laid in 1832 in New York by John Stephenson, to assist horses pulling buses through dirt roads, especially in wet weather when muddy. By laying rails, a horse could easily pull a load of 10 tonnes, rather than 1 tonne on a dirt road. The evolution of street tramway tracks paralleled the development from horsepower to mechanical, especially electric power. In a dirt road, the rails needed a foundation, usually a mass concrete raft. Highway authorities often made tramway companies pave the rest of the road, usually with granite or similar stone blocks, at extra cost. The first tramways had a rail projecting above the road surface, or a step set into the road, both of which were apt to catch the narrow tyres of horse drawn carriages. The invention by Alphonse Loubat in 1852, of the grooved rail enabled tramways to be laid without causing a nuisance to other road users, except unsuspecting cyclists, who could get their wheels caught in the groove. Electrification needed other developments, most notably heavier rails to cope with electric tramcars weighing 12 tonnes rather than the 4 tonne horse drawn variety, switching points, as electric trams could not be pulled onto the right track by horses, and the need for electrical connections, to provide the return path for the electric current, which was supplied through an overhead wire. Prior to the universal introduction of electric power, many tramways were cable hauled, with a continuous cable carried in a conduit under the road, and with a slot in the road surface through which the tram could clasp the cable for motion. This system can still be seen in San Francisco in California and the Great Orme in Wales. This needed a rather more substantial track formation. In some cities where overhead electric cables were deemed intrusive, underground conduits with electrical conductors were used. Examples of this were New York, Washington, Paris, London, Brussels, and Budapest etc. The conduit system of electrical power was however very expensive to install and maintain, although Washington DC did not close until 1962. Attempts were made with alternative systems not needing overhead wires. There were many systems of “surface” contact, where studs were set in the road surface, and energised by a passing tram, either mechanically or magnetically to supply power through a skate carried under the tram. Unfortunately these systems all failed due to the problem of reliability and not always turning off after the tram had passed, resulting in the occasional electrocution of horses and dogs. In the last few years a new system of surface contact has been installed in the Bordeaux tramway by ALSTOM. A Grooved rail or Girder rail, is a special rail designed for tramway or railway track in pavement or grassed surfaces (grassed/lawn track). The grooved girder rail has been the main system for street tracks but where new systems or extension are planned the volume of under-street utility plant, cables, pipes, ducts drains etc, means that a concrete raft foundation increases installation costs, since the utilities are inaccessible, and normally need to be relocated. In the years since the first tramway, highway pavement design has progressed around the world. Flexible and rigid pavements are capable of carrying 80 tonne goods vehicles with 15 tonne axle loads at 100 km/h. Using a 19th century tram track system, which destroys a robust pavement, and then requires reinstatement adds costs to tramway track installation and maintenance. To work with strong highway pavements, the LR55 system was developed, which can be simplified into ”glue” into the road rail. A comprehensive battery of laboratory testing was completed, with up to 80 tonne axle loading, and cyclic testing for 200 million cycles at 25 tonne axle loading. A test section was installed in Rotherham Bus station in 1993, where some 1 million bus movements a year passed over it. In 30 months it experienced the same heavy road vehicle impacts as 30 years in a typical radial or arterial road. A section of LR55 was installed in the Sheffield Super-tramway in March 1996, to replace a section of conventional track that had failed after just one year of operation. This has been maintenancefree, shown little sign of wear and has been predicted to last at least 30 years. Being a mass/spring/mass/spring system, the LR55 offers noise and vibration reduction of some 30 dB. It is also electrically isolated from the ground with a track resistivity of greater than 1000 Ωkm. This means that any stray currents will be in the micro amp range. Finally as a fully sprung track form, the LR55 significantly reduces track corrugations and uneven wear, thereby extending the life of the rails without the need for regular grinding to maintain an acceptable ride quality.
Figure 70: LR55 Section
Figure 71: Rail in Rotherham Bus Station
Page 52 of 259
Figure 72: Rail Pressure Graph
The LR55 track does not need a concrete raft foundation, so under-street utilities are still accessible and therefore do not need relocation. The LR55 is also quicker to lay, and can be laid one rail at a time to minimise traffic management problems.
Figure 73: Grassed Track
Figure 74: Grooved rail gauntlet track on a street tramway in Mannheim, Germany
Page 53 of 259
3.3 Bullhead Rail The United Kingdom introduced a type of rail, which was not used elsewhere - apart from a few UK designed railways. This was known as "Bullhead" rail that sit in chairs. These were somewhat figure-8 in cross-section — wider at top and bottom (known as the head and foot respectively) and smaller in the middle (the web).
Figure 75: Cross-section of the now obsolete bullhead rail
In late 1830s, railway lines in England had a vast range of different patterns. One of the earliest lines to use double-headed rail was the London and Birmingham Railway, which had offered a prize for the best design. If it were true that the rail could be turned over when the running surface became worn, the argument lost its validity as it evolved into the bullhead rail, with a heavier profile to the top edge. The lower edge also wore in patches where it was borne on the chairs. Although it became the standard for the British railway system until the mid-20th century, there seems to be nothing in the literature about any other advantages it may have had. Bullhead rail was originally designed with reuse in mind. It was intended that it would be turned over when the top had worn but this proved impossible because the underside also wore where it had been secured to the sleeper. This idea behind bullhead rails that because both the top and bottom of the rails were the same shape, when one side of the rail became worn, the rail could be turned over to the unused side thus extending the rail's lifespan turned out wrong simply because the bottom head turned out to get dented, rendering the original idea useless. Since now the turning over requirement was no longer needed, bullhead rails came to have a flat base (narrower than flat-bottomed rail), and the top part has curved edges that fit the profile of the train wheels. The standard design was an elastic spike with a sprung curved top, which secures the rail. Bullhead rail has to be mounted on a special cast iron "chair" and secured by a spring steel clip called a "key" wedged between the rail web and the chair. In traditional British practice using bullhead rail, cast metal chairs were screwed to the sleepers. Keys (wedges of wood or sprung steel) were then driven in between chair and rail to hold it in place. The chairs are secured to the sleepers by "coach screws". This was common practice on British railways until the 1950s, but is now largely obsolete.
Figure 76: Track using the UK Bullhead rail profile.
Page 54 of 259
3.4 Flanged T-Rail Iron-strapped wooden rails were used on all American railways until 1831. Col. Stevens conceived the idea that an all-iron rail would be better suited for building a railroad. He sailed to England, the only place where his flanged T rail (also called T-section) could be rolled. Railways in England had been using a similar rail that the ironmasters had produced. In May, 1831, the first 500 rails, each 15 feet long and weighing 36 pounds per yard, reached Philadelphia and were placed in the track, marking the first use of the flanged T rail. Afterwards, the flanged T rail became employed by all railroads in the United States. The modern version is made of an alloy of steel that is much heavier and stronger than the original rail. Col. Stevens also invented the hooked spike for attaching the rail and the sill plate (tie plate) to the crosstie (or sleeper). Presently, the screw spike is being used widely in place of the hooked spike, perhaps because it is possible to install the screw spike by using a labour-saving machine that replaces salaried workers. At the present time, crossties or sleepers constructed of concrete are in use in some places. The use of creosote as a treatment for wooden crossties has been declared to be detrimental to the health of people and plants. The crossties or sleepers are embedded in ballast in order to provide stability and drainage.
3.5 Vignoles Rail Vignoles rail is the popular name of the flat-bottomed rail used internationally for railway track, recognising engineer Charles Vignoles who established it in Britain. Col. Robert L. Stevens, the President of the Camden and Amboy Railroad, first introduced flat-bottomed rail in America in 1830. There were no steel mills in America capable of rolling long lengths, so it was manufactured in Britain. Charles Vignoles observed that wear was occurring with steel rails and steel chairs upon stone blocks, the normal system at that time. In 1836 he recommended flat-bottomed rail to the London and Croydon Railway for which he was consulting engineer. His rail had a smaller cross-section to the Stevens rail, with a wider base than modern rail, fastened with screws through the base. Other lines that adopted it were the Hull and Selby, the Newcastle and North Shields, and the Manchester and Bolton. When it became possible to preserve wooden sleepers with mercuric chloride (a process called "Kyanising") and creosote, they gave a much quieter ride and it was possible to fasten the rails directly using clips or rail spikes. Their use spread worldwide and acquired Vignoles' name. The standard form of rail used around the world is the "flat bottom" rail. It has a narrower top or "head" and a wide base or "foot" that can rest directly on sleepers. It has a flat base and can stand upright without support.
Figure 77: Cross-section of flat-bottomed Vignoles rail
The photo below shows a flat-bottomed rail secured by a Pandrol clip to a baseplate under the rail on a concrete sleeper. Flat bottom rails can also be "spiked" directly to the sleepers. A wide-headed nail is driven into the sleeper on each side of the rail so that the heads of the spikes hold the foot of the rail. Long stretches of track were laid in record times across the US in the pioneering days of railroad development using this method of securing rails to "ties". Nowadays, heavier loads and faster trains require more sophisticated systems.
Page 55 of 259
Figure 78: Pandrol clip holding rail to concrete sleeper
Figure 79: Trackwork in Jalandhar, India – notice the baseplate and the Pandrol clips
Page 56 of 259
4
Construction
4.1 Fastening rails to sleepers/ties There are several methods used to fasten rail to sleepers. First sleepers are laid across the grade at regular intervals with the rails then laid atop and perpendicular to them. If the ties are of wood, then there are several methods used to fasten rails to them. A flat-bottomed rail is usually held to the sleeper with a baseplate, a metal (cast-steel) plate screwed or bolted to the sleeper, with either spikes or bolts driven through them into the ties to clamp down the rails. For lower cost of construction, flat-bottomed rails are directly laid onto sleepers. Historically, railroads with American-inspired technology have used driven rail spikes, which are very large nails with overhanging heads to clasp the flat-bottomed rail and to hold the rail to the sleeper. These are cheaper and simpler to install but can loosen if the tie rots, much more easily than the British chair does. Using very large and solid creosoted ties or using another rot-proofing preservative mitigates this. European railways favour square-headed bolts that are screwed into the wood. Besides spikes and bolts used for wood, a variety of different types of heavy-duty clips are used to fasten the rails to the underlying baseplate, one common one being the Pandrol fastener (Pandrol clip) named after its maker and shaped like a sturdy, stubby paperclip. This is commonly used in the case of reinforced concrete and pressed-steel ties. A resilient rubber pad is inserted between the rail and the base plate and around the securing clip. This is done for two reasons: to give a smoother ride and where required to provide insulation for the track circuits where installed and prevent the sleeper from shorting the track circuit; a low voltage passes through the rails for signalling purposes. This is different from a "traction current," which powers electric trains. Following this, additional ballast is added to fill the spaces between and around the ties to anchor them in place. The ties act as anchors and spacers for the rails while providing a slight amount of give to accommodate weather and settling. The ties are said to be “floating” at the top of the ballast. Failure of a single tie is generally insignificant to the usability and safety of rails. Some railroads used a “date-nail” coded to identify the age of the railroad tie (that was usually laid down in sections) by hammering it into the railroad tie after installation for maintenance purposes. Another method of fastening is the Vossloh Tension Clamp. In recent years, methods have been developed to put tracks on concrete without using conventional sleepers or track ballast. While this method's construction cost is high, this system is expected to have significantly lower maintenance costs than conventional tracks. It is mainly used on high-speed lines and in tunnels with difficult maintenance access. Pictures below shows a traditional British practice at Cardiff Bay railway station using a fishplate between two sections of jointed bullhead rail with a rail chair screwed into a wooden sleeper. The keys are on the opposite side of the rail (not visible).
Figure 81: Spring clip & spike with baseplates on adjacent sleepers at welded joint
Figure 80: Pandrol Clip
Figure 83: Traditional British practice at Cardiff Bay railway station shows a fishplate between two sections of jointed bullhead rail with a rail chair screwed into a wooden sleeper. The keys are on the opposite side of the rail (not visible).
Figure 82: Screwed rail attachment
Page 57 of 259
Figure 84: BNSF Railway spiker in operation in Prairie du Chien, Wisconsin. The machine is driving spikes on both sides of the rails after the ties were replaced.
4.2 Joining the Rails Much of the work of maintaining the track was at the joints, especially as the stiff rails became dipped, and the joint sleepers took a hammering. Prewar experiments with long welded rail lengths were built upon, and in the years from 1960 long rail lengths were installed, at first on hardwood sleepers but soon on concrete sleepers. In this pioneering stage some catastrophic mistakes in detailed design were made, but from about 1968 continuous welded rail became a reliable standard for universal installation on main and secondary routes. The form adopted used pre-stressed concrete sleepers and a 110A rail section – a slight improvement on the 109 rails previously used – the A was to distinguish it from the British Standard 110 lb/yd rail section, which was unsuitable. Rail fastenings eventually converged onto a proprietary spring clip made by the Pandrol Company which was the exclusive form of fastening in Britain for about 30 years. The welded track was to be laid on six to twelve inches of crushed stone ballast, although this was not always achieved, and the bearing capacity of the formation was not always taken into account, leading to some spectacular formation failures. A further enhancement to the rail profile produced the 113A section which was the universal standard until about 1998; detail improvements to the sleepers and ballast profile completed the picture and the general form of the track had stabilised. This format is now in place over 99% of first-class main lines in Britain. Nowadays, rail is welded into long lengths, which can be up to several hundred metres long. Expansion is minimised by installing and securing the rails in tension. Provided the tension is adjusted to the correct level, equivalent to a suitable rail temperature level, expansion joints are not normally needed. Special joints to allow rail adjustment are provided at suitable locations as shown in the photo below. Adjustment switches are also provided to protect turnouts and at locations where changes in rail design or size occur. Rail tends to creep in the main direction of travel so "rail anchors" (US: "anti-creepers") are installed at intervals along the track. They are fitted under the rail against a base plate to act as a stop against movement.
Page 58 of 259
Figure 85: Expansion joints are provided in running rails to allow for temperature changes. The additional rails in the centre of the track are bolted to the sleepers to prevent the sleepers being shifted by rail expansion.
There are different ways of combining rails together to form tracks, as described in the sections below.
4.2.1
Jointed track
A jointed track is made up of two joint bars (more commonly called angle bars) or fishplates bolted through the web of the rail. The joint bars prevent lateral or vertical movement of the rail ends and permit the longitudinal movement of the rails for expanding or contracting. The purpose is to hold the two facings ends of consecutive rails in place and act as a bridge or girder between them. In this form of track, lengths of rail, usually around 20 metres (60 feet) long, are laid, fixed to sleepers and joined to other lengths of rail with steel plates known as fishplates (UK) or joint bars (N.A.). Fishplates or joint bars are usually 60 centimetres (2 feet) long, and are bolted through each side of the rail ends with bolts (usually four, but sometimes up to six.) Small gaps known as expansion joints are deliberately left between the rails to allow for expansion of the rails in hot weather. The holes through which the fishplate bolts pass, are oval to allow for expansion. Joint bars are matched to the appropriate rail section. Each rail section has a designated drilling pattern (spacing of holes from the end of the rail as well as dimension above the base) that must be matched by the joint bars. Although many sections utilize the same hole spacing and are even close with regard to web height, it is essential that the right bars are used so that fishing angles and radii are matched. Failure to do so will result in an inadequately supported joint and will promote rail defects such as head and web separations and bolthole breaks. Most of the older tracks are jointed. In the UK, about 35% of track is still jointed, although this is continuously falling as new rail is installed. Rails were normally laid in standard lengths bolted together by what are called fishplates in the UK or splices in the US. The joints allowed sufficient space for expansion as they were provided at 60-foot intervals in the UK and 39 foot in the US, allowing them to be carried in a standard 40 ft flat wagon. The joints were always staggered in the US whereas the UK placed them side-by-side. The result of the US staggered joints can be seen in the curious rolling motion of freight cars running on poorly maintained track. The reason for the staggering is that, in the US it was determined that after jointed rail has been in place for a time it starts to drop and creates a depression. When a wheel falls into the depression and begins to climb out again it exerts a force. If the two joints were in parallel this force would be much larger and the joints might snap. This is not considered a problem in the UK and Europe, probably because of the lighter axle loads. Historically, North American railroads until the mid to late 20th century used sections of rail 39 feet (11.9 m) long so they could be carried to and from a worksite in conventional gondolas, which often measured 40 feet (12.2 m) long; as car sizes increased, so did rail lengths. When trains pass over jointed tracks, they make a "clickety clack" sound because of the small gaps left between the rails. Unless it is well maintained, jointed track doesn't have the ride quality of welded rail, and is unsuitable for high-speed trains. A major problem is of cracking around the boltholes, which can lead to the railhead breaking. This was the cause of the Hither Green rail crash, which caused British Railways to begin converting much of its track to Continuous Welded Rail. However, jointed track is still extensively used in poor countries due to lower construction cost and lack of modernisation of their railway systems and is still used on lower-speed lines and on sidings. The joint is considered the weakest part of the track structure and are being slowly eliminated wherever possible. Stronger methods of joining two rails together have been developed. When sufficient metal is put into the rail joint, the joint is almost as strong as the rest of the rail length. This is achieved by welding the rail sections together forming a continuous rail can eliminate the noise generated by trains passing over the rail joint described as the “clickety clack” of the railroad track. There are two kinds of welding processes in use: thermite welding and flash-butt welding.
Page 59 of 259
Figure 87: Alternative view of track joints
Figure 86: Track Joint
4.2.1.1
Rail Movement Joints
Rail movement joints are required when tracks are layed across engineering structures such as bridges and viaducts. These structures are exposed to changes in lengths due to ambient influences like traffic load, temperature and wind. These influences sometimes lead to angular rotations of the end spans in the abutment. Rail movement joints are installed to bridge such length variations and - if required - to accommodate angular rotations of the end spans. VAE have developed many types of rail movement joints, as follows:
Rail movement joints with longitudinally moveable stock rails
Figure 88: Rail movement joints with longitudinally moveable stock rails
Page 60 of 259
Special rail movement joints for large bridges have been developed with corresponding longitudinal and rotational movements of the end span. Compared to conventional products of this type, the VAE developed product has the following features:
The stock rails move longitudinally in two symmetrically arranged cast troughs with integrated switches Wheel transition like that in a switch device of a turnout No gauge widening No check rails required For large bridges the rail movement joint is attached to the supporting structure of the bridge with large rotations of the end span by means of a flexible spline girder. Arising angular deviations are elastically accommodated in vertical and horizontal directions and thus the sensible area of the length modifications in the rails is kept free of deformations. Use of sledges between abutment and the bridge for expansion lengths of
up to ± 600 mm 1 sledge up to ± 900 mm 2 sledges from ± 900 mm min. 3 sledges
Levers below the sledges make sure that the lengths of the gaps is evenly spread. At the same time, small rotations of the end span are accommodated. The advantages offered are:
State-of-the-art solution for large movements High wear allowance Extremely low maintenance
Rail movement joints with longitudinally moveable asymmetrical switches
Figure 89: Rail movement joints with longitudinally moveable stock rails
Page 61 of 259
The advantages offered are:
Proven and economical solution for medium-length movements Suitable for standard fastening systems Overrunning in both directions at track speed possible High wear allowance
Rail movement joints “Scarf type”
Figure 90: Rail Movement Joints "Scarf Type"
The expansion rails for small and medium range of movements are made from halved flat-bottom rails or full-head rails. Some railways use this type of rail movement joint for securing the end of a continuously welded track. For securing the gap in the running edge (dependent on design) a check rail is required for medium expansion lengths. The advantages offered are:
4.2.2
Short length Economical solution for short movements Depending on design, no welded joint
Insulated joints
Figure 91: Insulated Joints
Where track circuits exist for signalling purposes, insulated block joints are required. Track circuits indicate the presence of trains on a section of track and are a key component of the signalling system. Insulated block joints are essential to break up the electrical sections of track circuits in the rails. They prevent the electric current from flowing between the ends of two adjoining rails thereby creating track circuit sections. Insulated joints use an insulated end post between rail ends to prevent the rail ends from shorting out. Insulated joints compound the weakness of ordinary block joints. Using specially made glued joints with all the gaps filled with epoxy resin increases the strength again. There are three types of insulated joints – continuous, non-continuous and bonded.
Page 62 of 259
4.2.2.1
Continuous insulated joints
Continuous insulated joints support the rail base continuously. No metal contact exists between the joint bars and the rails. Insulated fibre bushings and washer plates are used to isolate the bolts from the bars. The joint bars are shaped to fit over the base of the rail. This type of insulated joint sometimes requires a special tie plate called an “abrasion plate” to properly support the joint in case of concrete sleepers that are prone to wear. It is a thin metal plate or seat situated between the rail sleeper and the elastomeric rail pad that insulates the rail from the sleeper. The plate may be bonded to the rail sleeper or a resilient gasket can be interposed between the rail tie and the plate.
Figure 92: Continuous Insulated Joint
4.2.2.2
Non-Continuous insulated joints
Non-continuous insulated rail joints don’t continuously support the rail base. A special insulating tie plate is required on the centre tie of a supported, non-continuous insulated joint. Metal washer plates are placed on the outside of the joint bar to prevent the bolts from damaging the bar. The two common kinds of non-continuous insulated joints are Glass fibre and Polyurethane encapsulated bar.
4.2.2.3
Bonded insulated joints
Figure 93: Insulated joint with square rail cut
Page 63 of 259
Bonded insulated joints in rails separate electric circuits in tracks and turnouts. As they are used in Continuously Welded Rail (CWR), they must be able to transfer longitudinal forces arising in the track. Insulated joints are available with square and angular cut. Generally they are supplied as prefabricated joints glued into short rail pieces. Insulated joints with square cut can also be made in the track. If bonded insulated joints are used the track must meet certain requirements regarding stability, good tamping and sleeper quality. A non-bonded insulated joint is a disturbing factor in the continuously welded rail, therefore bonded insulated joints are used with four or six bolts. All insulated joints are checked for their electrical resistance. If a high number of joints is supplied, even destructive tests like tensile test and fatigue tests are conducted. The insulated joint consists of two separated rail pieces, two steel fishplates, the corresponding number of high-tensile bolts, insulating pads, insulating bushes and end posts made from synthetic material and glass fibre mats. These can be used with either wooden or concrete sleepers and with all common rail sections. The joints are heat treated, in that they are hardened or preferably made from head-hardened rails. The bonding is carried out with appropriate bonding and hardening agents. The ideal manufacture is carried out in the factory to ensure ideal conditions of cleanliness, temperature and manufacture procedure because the rail ends and the surface of the steel parts to be bonded must be spotlessly clean. However upon clear instructions of the supplier manufacture can also be done at site if need be. As an alternative to the insulated joint, audio frequency track circuits can be employed using a tuned loop formed in approximately 20 m of the rail as part of the blocking circuit. Another alternative is the axle counter, which can reduce the number of track circuits and thus the number of insulated rail joints required.
Figure 94: Insulated joint with angular rail cut
4.2.3
Continuous Welded Rail (CWR) Track
Most modern railways use continuous welded rail (CWR). Because there are few joints, this form of track is very strong, gives a smooth ride, reduces wear, reduces damage to trains, eliminates noise associated with rail joints and needs less maintenance. Welded track has become common on main lines since the 1950s. Because of the increased strength of welded track, trains can travel on it at higher speeds and with less friction. Welded rails are more expensive to lay than jointed tracks, but have much lower maintenance costs. The rails are welded together by utilising either of the two methods, the thermite reaction method or flash butt welding method to form one continuous rail that may be several kilometres long. Rails expand in hot weather and shrink in cold weather. Because welded track has very few expansion joints, if no special measures are taken it could become distorted in hot weather and cause a derailment (a condition known in America as sun kink, referred in Britain as "buckling"). To avoid this, welded rails are very often laid on concrete or steel sleepers, which are so heavy they hold the rails firmly in place. After new segments of rail are laid, or defective rails replaced (welded in), the rails are artificially stressed while being welded. Defective rails are removed and the need for re-stressing is calculated. The amount of stress put into the rail is dependent upon the temperature at the time and is calculated such that the rail will become stress-free when the temperature is 27oC. These rams can work at over 5000 psi and gaps in the rail of over 12 inches (300 mm) can be closed in certain circumstances. The stressing process involves either heating the rails causing them to expand or stretching the rails with hydraulic rams, which hold the rail whilst it is being welded. They are then fastened (clipped) to the sleepers in their expanded form. This process ensures that the rail will not expand much further in subsequent hot weather. In cold weather, the rails try to contract but because they are firmly fastened, they cannot do so. In effect, stressed rails are a bit like a piece of stretched elastic firmly fastened down. Great attention is paid to effectively compacting the ballast, particularly the shoulder over the ends of the sleepers, to prevent them from moving. Even so, in extreme weather, foot patrols monitor sections of track known to be problematic. Engineers try to heat the rail to a temperature roughly midway between the average extremes of hot and cold (this is known as the 'rail neutral temperature'). If temperatures reach outside normal ranges however, welded rail can buckle in a hotter than usual summer or can actually break in a colder than anticipated winter. Joints are used in continuously welded rail when necessary; instead of a joint that passes straight across the rail, producing a loud noise and shock when the wheels pass over it, two sections of rail are sometimes cut at a steep angle and put together with a gap between them - a breather switch (referred to in Britain as an expansion joint). This gives a much smoother transition yet still provides some expansion room.
Page 64 of 259
Figure 95: Welded rail joint
5
Railway Track Layouts
5.1 Railroad Switch/Point/Turnout 5.1.1
History
On early lines, vehicles were moved between tracks by means of sliding rails. The switch as we know it, was patented by Charles Fox in 1832. Prior to the widespread availability of electricity, switches at heavily travelled junctions were operated from a switch tower (signal box) constructed near the tracks through an elaborate system of rods and levers. The levers were also used to control semaphore railway signals to control the movement of trains over the points. Eventually, mechanical systems known as interlocking were introduced to make sure that a signal could only be set to allow a train to proceed over points when it was safe to do so. On some low-traffic branch lines, in self-contained marshalling yards, or on heritage railways, switches may still be operated in this way.
5.1.2
Overview
When two vehicles encounter one another on a narrow road, one needs to turn out of the road to let the other pass. Similarly, in railway engineering, an appliance is necessary to allow a train to move out from one track to another. A railroad switch, turnout or [set of] points is a mechanical installation, enabling railway trains to be guided from one set of rail or tramway tracks to another at a railway junction. By analogy, in America this appliance came to be known technically as a turnout although it is popularly called a switch, in the same vein. In Germany, what wagons did when they met was weichen, so the railway appliance became known as a Weiche. In Britain, however, attention was focussed on the movable, pointed rails that were known from their shape as points, and this became the name of the appliance, though really there is no actual term for the complete appliance there. In France, the points were “les aiguilles”, the "needles," and this was the word that was adopted there. Most people will talk of "switches" or "points," while only an engineer will refer to a "turnout." Also, the points themselves are technically switch rails, of which the point is just one end. Switches are a vital part of railroading. Without them, we’d be confined to running trains in simple loops. They are necessary any time one wants to send a train in an alternate direction. They make it possible to store one train on a siding and run another around it, or any other basic operation. They're essential if trains need to more than just run around in circles. Unfortunately, they're also the leading cause of derailments and accidents. To understand what makes a switch function and malfunction one needs to know how a switch works and the many kinds of switches there are.
Page 65 of 259
Figure 96: GNER_HST_and_Northern_156479_2005-10-08
Figure 97: Railroad track in Birkenau (Auschwitz II) concentration camp in 2001
Page 66 of 259
Figure 98: Turnout
Page 67 of 259
Figure 99: West_India_Quay_DLR_station_from_Canary_Wharf_DLR_station_2005-12-10
Figure 100: Docklands Light Railway junction north of West India Quay
Page 68 of 259
Figure 101: Left: GNER Intercity 125 HST from Newcastle to Edinburgh via the Tyne Valley Line to Carlisle. Right: Northbound Class 221 Virgin Voyager DEMU heading for Newcaslte. Both trains are crossing the River Tyne on the King Edward VII bridge
Figure 102: LU-1996ts-Wembley_Park_Siding_2005-12-10
Page 69 of 259
Figure 103: Netley Railroad
Figure 104: Northern_Rail_DMU_156463_at_Sunderland_2005-10-10_03
Page 70 of 259
Figure 105: Sign of point
Figure 106: Silverlink_313123_at_Kensington_Olympia_01
Page 71 of 259
Figure 107: Taipei MRT railroad point in Damshui Station
Figure 108: Welsh Marches Line north of Craven Arms station
Page 72 of 259
Figure 109: "Serna" junction station turnout (Salamanca) (separation point of railway lines to Fuentes de oñoro and Plasencia.)
Figure 110: "Serna" junction station – symmetrical turnout
Page 73 of 259
Figure 111: "Serna" junction station: Convergent switch
Figure 112: Castle Cary railway station – view west from footbridge
Page 74 of 259
Figure 113: Castle Cary railway station - view west from footbridge
Figure 114: View west from Castle Cary railway station
Page 75 of 259
Figure 115: Castle_Cary_railway_station_viewed_from_car_park_-_02
Figure 116: Carlisle_railway_station_2005-10-08_01
Page 76 of 259
Figure 117: Bristol-Birmingham-Derby Line north of Filton Abbey Wood
Figure 118: Which way?
Page 77 of 259
Figure 119: Westbound freight train at Bristol Parkway
Figure 120: Boldon West Junction
Page 78 of 259
Figure 121: Variety of railroad turnouts
Figure 122: A scene from Indian Railways
Page 79 of 259
Figure 123: Compensate to maintain tension in the cables that work the switches
Figure 124: Typical track plan of a turnout
Page 80 of 259
5.1.3
Turnout Components
In the railway trade, turnouts are referred to as "switch and crossing work". The word "turnout" is therefore safer to use in order to avoid "points" (UK) or "switches" (US). In the UK and Commonwealth countries, the term “point” refers to the entire mechanism, whereas in North America the term refers only to the movable rails. In any case a turnout is used to describe a junction in tracks where lines diverge or converge, or more accurately an arrangement of a pair of switches and crossing by means of which rolling stock may be diverted from one track to another.
Figure 125: Typical Vossloh Turnout Components
5.1.3.1
Basic Parts
A turnout can be seen to have three distinct zones as below:
Figure 126: Turnout Zones
Page 81 of 259
The principal parts of a turnout are shown in the picture below:
Figure 127: Simple turnout with names of principal parts
The long, continuous rails that form the outside edges of the switch are called the stock rails. The movable parts that route the trains one way or the other are called the points or point blades. The throw bar or tie bar ties the points together and controls their movement from side to side. The crossing in the middle where the rails meet is called the frog. The rails between the points and the frog are called the closure rails. The small lengths of rail along the stock rails (opposite the frog) are called checkrails or guard rails. These keep the wheels from "picking the frog" and heading the wrong way, leading to a derailment. On a typical switch, the straight path is called the main route, and the path that curves away is called the diverging route. In a railroad, the sharpness of this divergent route is identified in one of two ways: either in terms of the radius, or by a number. The larger the frog angle, the wider is the switch.
5.1.3.2
Points (point blades)
The points (point blades) are the linked, tapering and movable rails lying between the diverging outer rails (stock rails), which guide the wheels towards either the straight or the diverging track. They are tapered on most switches but on stub switches, where they have square ends. The moving part of the turnout is the switch "blade" or "point", one for each route. The two blades are fixed to each other by a tie bar to ensure that when one is against its stock rail, the other is fully clear thus providing room for the wheel flange to pass through cleanly.
Figure 128: This detail of a switch shows the pair of tapered moveable rails known as the switch points (switch rails or point blades)
Page 82 of 259
On either side of the crossing, wing rails and checkrails are provided to assist the guidance of the wheelsets through the crossing. The moveable tongues of a set of points consist of two rails that are fixed in place at one end at what is called the frog and that can slide sideways at the other end. The tongues are not hinged, but bend along their length. Switching of points is done using a points actuator that uses two rods to simultaneously pull the two tongues to one side. The tongues move about 12 centimetres from side to side.
5.1.3.3
Frog (Common Crossing)
Figure 129: Mathematical Representation of a Frog
Figure 130: Frog Crossing
Figure 131: A flangeway
Let us consider a turnout from a straight track to a track diverging to the left for concreteness. The straight track supports and guides the wheels with the help of the wheel flanges. Somehow, at the turnout, the flanges must cross the left-hand rail, while the wheels are continuously supported and guided. The device that allows the left-hand flange to pass is the first encountered, and is called the switch. The right-hand flange later reaches the crossing or frog and crosses and then crosses it. The American term "frog" comes from the supposed appearance of early cast-iron crossings with their four splayed legs.
Page 83 of 259
The frog (common crossing) refers to the crossing point of two rails. This can be assembled out of several appropriately cut and bent pieces of rail or can be a single casting. A frog forms part of a railroad switch, and is also used in a level junction. The frog is a point of weakness because the wheels are unsupported for a short distance and can inflict wear and damage. There is also a small risk that the wheels may go the wrong way. The crossing can be cast or fabricated. Rails are usually made of steel with a large iron content but a little manganese is added to crossings and some heavily used rails to increase resistance to wear. Below is a photo of an example of a cast manganese crossing.
Figure 132: Frog
Page 84 of 259
The use of the word "frog" derives from the appearance of the triangular assemblage of rails which recalls the frog of a horse's hoof. Another origin of the term “frog” gives its name to the frog war, a conflict that occurs when a railroad company attempts to cross the tracks of another. Another reason given for the use of the word “Frog” to describe this device that it is where the wheel “jumps” over the rail, like a frog jumping. In French, this device is also known as a “bifurcle”—the location where the rails bifurcate in a turnout. The frog occurs in all kinds of turnouts, consisting of rails making an angle F, the frog angle, with grooves cut in the heads of the rails to allow the flanges to pass. The wheel treads are wider than the flangeways, and so the wheel is more or less supported at all times. The flangeway gap is the space between the inner edge of a rail and the crossing surface. The gap must be of sufficient width to permit a locomotive or rail car wheel to pass through. If there is inadequate space, a derailment will occur. From the perspective of rail safety, the flangeway gap must be at least three inches (narrower gaps are permissible for rights-of-way used exclusively by light-rail equipment). Through experience, the railroads expect that if a crossing with a three inch flangeway gap is constructed, wear will result in the gap widening by as much as an additional inch. The toe of the frog is on the side of the switch, while the heel is the other end. The rails from the switch side form the wings on each side of the tongue of the frog. The mouth is the space between the rails approaching the frog, while the throat is the point of closest approach. The point of the frog is generally rounded off to a width of 1/2" at the actual point of the frog. The point where the flange edges of the two rails meet when extended is the theoretical point. In America, the frog angle is specified by the frog number, which is the ratio of the length to the width, n = PH/AB. This is the ratio of the length to the sum of heel and toe spreads. The frog angle F is easily seen to be related to n by tan(F/2) = PH/2AB = n/2, or F = 2 tan-1(1/2n). Practical frog numbers range from 5 to 20, but yard frogs are seldom less than number 8, and mainline frogs seldom less than 12. Frogs have standard dimensions that are given in Reference 2. In the diagram above, k and h are the toe and heel distances measured to the theoretical point. Brittle cast-iron frogs were very early replaced by built-up frogs made of rail, bolted together with spacers. These were hard to inspect, and could fail from cracking, but were much safer than cast iron. Later, cast steel frogs were introduced and proved very satisfactory. Most frogs used now are cast steel. Manganese steel gives great wear resistance because of its extraordinary work hardening.
Figure 133: Frog in abandoned station in Spain
Page 85 of 259
Figure 134: Cast frog
Figure 135: Old mounted frog with cast middle
Page 86 of 259
Figure 136: Mounted frog
Figure 137: A cast manganese crossing/frog in a standard UK turnout. Special baseplates have to be provided at turnouts for switch blades, check rails and crossing work.
Page 87 of 259
Figure 138: mounted frog with welded point
Page 88 of 259
5.1.3.4
Guard Rail (Check Rail)
A necessary accessory to the frog is a device to ensure that the flange of a wheel does not strike the point of the frog, but is carefully guided to one side. This is most usually done by guard rails, which keep the backs of the opposite wheels far enough away, as shown in the figure. A guard rail (check rail) is a short piece of rail placed alongside the main (stock) rail opposite the frog. These exist to ensure that the wheels follow the appropriate flangeway through the frog and that the train does not derail. Generally, there are two of these for each frog, one by each outer rail. Guardrails are not required with a "self-guarding cast manganese" frog, as the raised part of the casting serves the same purpose. These frogs are for low-speed use and are common in rail yards. The check rails are necessary to guide the wheels in the area of rigid crossings. Sometimes, check rails are also installed as guard rail on the inside of small-curved tracks in order to relieve the outside rail and to minimize wear. Check rails are used with or without superelevation relative to the top of the rail.
Figure 139: Functioning of Guard / Check Rail
Figure 140: Check gauge
The check gauge c measured from the back of the wheel must be maintained at a value that will ensure flange clearance. Raised edges on the frog itself may press on the outside of the wheel tread for the same purpose; this is called a self-guarded frog. Self-guided frogs are only used at low speeds, say 30 mph or less. If the frog angle is small, it may be necessary to use moving point frogs in which the unused flangeway is completely closed by moving a "knee" to one side. This is effective, but requires additional mechanism. A "spring frog" holds one flangeway closed by spring pressure on a movable wing rail. When a wheel goes this way, the wing rail is forced out of the way so the flange can pass. These are very commonly used on main lines, and are sprung for the straight-through movement. Diverging movements are made at low speed. Spring frogs are not used at junctions, of course.
Figure 141: Check / Guard Rail
Page 89 of 259
Figure 142: Guard Rail
Page 90 of 259
Figure 143: The frog (left) and guard rail (right) can be seen in this detail of a switch.
Figure 144: Extended wing rail as the check rail
Page 91 of 259
Figure 145: Double frog with check rail
5.1.3.5
Joints
Joints are used where the moving points meet the fixed rails of the switch, i.e. points are joined to the closure rails by bolts thorough a “joint bar” (North American usage) or “fish plates” (UK)). They allow the points to hinge easily between their positions. Originally the movable switch blades were connected to the fixed closure rails with loose joints, but since steel rails are somewhat flexible it is possible to make this join by thinning a short section of the rail itself. This can be called a heelless switch. Joints are not required for electrically operated switches, as they have enough power just to bend the rail.
Figure 146: The railroad switch with joints, designed for manual operation. The enlarged part (right bottom corner) show the joint construction. Military railway near Dubendorf, Switzerland
Page 92 of 259
5.1.3.6
Throwing a Switch - Switch Stands and Targets
That brings us to the most important aspect of the switch, the switch throw mechanism. This mechanical device holds the points against the stock rail causing the trains to travel in the intended direction. There are three basic kinds of switch throw: rigid, sprung, and rubber. The rigid throw moves the points against the rails and firmly holds them there. The points can't be opened or moved without moving the switch throw. A sprung throw holds the points against the rails, but allows them to be opened by a train travelling through the switch in the "wrong" direction. Once the train passes, the point springs back to their original position. The third kind of throw - the rubber throw - is a variation of the spring switch. With this kind of throw, if a train comes through the switch with the points against it, it will merely push the points open to the opposite direction, where they will stay once the train has cleared.
Figure 147: This rigid, ground-throw switch machine on the Horovitz's Ogden Botanical Railway is designed to hold the points against one rail or the other, so that trains can pass smoothly through. The machine is rigidly attached to the throw bar to firmly set the points against the stock rails.
Figure 148: Railway turnout with electric throw
Page 93 of 259
Figure 149: dovetail-shaped locking of the switch blades in opened position
A points lever, ground throw, or switch-stand is a lever and accompanying linkages that are used to align the points of a switch manually. This lever and its accompanying hardware is usually mounted to a pair of long sleepers that extend from the switch at the points. They are often used in a place of a switch motor on infrequently used switches. In some places, infrequently used points may be operated from a ground frame. To prevent the tampering with of these switches by outside means, these switches are locked up when not in use.
Figure 150: Hand-Throw Switch Stands
Page 94 of 259
The mechanism for the hand operation of turnouts is usually called a switch stand in America. It usually converts a rotary motion about a horizontal or vertical axis to a linear motion, moving the switch rails by means of the operating rod, and usually includes some sort of switch target to make its position evident to an approaching train or a switchman [we'll assme this includes the switch lamp as well]. The distance moved by the switch rails is the throw of the switch, around 4-3/4 in or 120 mm. Some examples of switch stands are shown at the right. If the handle moves a distance D while the throw is d, the ratio of the forces is the ideal mechanical advantage D/d. The harp switch stand was an early type, often used with stub switches, and is a simple lever of the first class. It can easily be applied to a three-throw switch. A pin was inserted to hold the lever in the desired position. The simple ground throw, called a parallel throw, operates through a 180° angle, and is held in position by the weight of the handle (but may be latched in each position as well). The more elaborate kinds may be "safety stands" (see below) and may have a vertical target rod. The "high" switch stand has a vertical axis that rotates through 90°. A popular model was known as the "High Star" switch stand, and there was a similar "Low Star" model. The operating handle folds down into a notch in the top plate, and can be padlocked there. In other types, the handle rotates a shaft driving the main shaft through gears, for a greater mechanical advantage. If d is the crank length, then √2d is the throw. Double cranks made connections easier. The connecting rod from stand to points was generally 6 ft long. When a vertical axis rotates through 90°, targets can be attached to indicate the position of the switch. A simple circular target is shown, which displays a red disc (or other shape) when the switch is set for divergence, and shows its edge when the switch is set for the straight. For the night indication, a lamp with four 4-1/8" lenses is placed on the top of the axis. The target rod tip is rectangular (1-1/8" x 13/16") so the lamp will go on only with the correct orientation. The long side is parallel to the rail for a closed switch. Such switch stands are used on main tracks, where the target and lamp must be high enough for visibility at a distance. When two switch stands come close together, one is high, the other low. The eccentric was used by the London & Birmingham Railway in the 1830's to control stub switches, which had been adopted as the safest choice. It gave a definite throw (twice the eccentricity) and a positive setting. The eccentric was rotated by a capstan-like device, the handle rotating through 180°. This mechanism was exported along with early railways to Europe, especially to France, where the employees operating switches at stations became known as gardes excentriques. This name long survived the eccentrics and stub switches. The switch may be held in either position by a spring, so that it "toggles" between the two positions. A lever is provided to change the position by a sharp pull that moves the switch rails to the intermediate position where they snap over to the other setting. Such switch operating mechanisms are used in Britain in yard tracks, and are not equipped with targets. When run through in the trailing direction, they automatically take the correct position if it is not already set. Generally, these switch stands are called "automatic"; that is, if run through they change to the correct position. An example has been given above. Another was the Ramapo switch stand, operated by a vertical handle and camming the crank rod. It rotated in steps of 90°. The sketch labelled "Racor" is only a suggestion of what these very commonly used patent low switch stands are like, of which Racor was one manufacturer. The handle rotates through 180° parallel to the track, while the vertical axis rotates through 90°, driven by bevel gears. The operating lever is held in a latch on either side, which can be released by a foot pedal. The latch can be padlocked to prevent tampering with the switch. The switch target can be a lamp with four lenses, 4 to 5 in in diameter, each surrounded by a coloured circular target, supported on this axis. At times, only the red or yellow target was used, while the other one was omitted. Some usual colours are shown in the diagram below:
Figure 151: Turnout Indicators
Page 95 of 259
The colours (a) were originally chosen when green was the colour of caution, and white for clear (before 1895). For main line switches, red was often used in place of green, as at (c). When yellow replaced green for caution, (b) was the result. These were the colours later used by the Pennsylvania Railroad. If green also replaced white, (d) was the result. For main line switches, (e) was popular, and was often used for all switches. (f) might be used for yard switches, if green was considered inappropriate. Actually, yellow and green is probably the best choice for yard switches, since it does not use red to mean something other than stop. The C&EI used white and yellow, the SP&S white and red, for switch lamp targets. For main lines, green and red is probably the best choice of colours. The AT&SF used green for a closed switch, red for an open main track hand-thrown switch, yellow for interlocked and yard switches. The yard switches used small rectangular yellow targets. Lunar white (bluish-white) was sometimes used for lamps on yard switches set for the straight route, as by the Southern, who used regular white (clear) for main line switches. Some typical simple targets for high switch stands usually made of painted sheet steel are shown below:
Figure 152: High-Switch Targets
The company identifications are not certain, but seem to be valid. The same company may well have used different targets in different times and places. Except where shown otherwise, there is no target for a "closed" switch, one set for the main line, in these examples. Such a target was often called blind. The target is displayed when the switch is "open," set for the divergence. The "SS" target is for a spring switch lined for the main line. The simple red disc is by far the most common target, used not only by the UP, but by the AT&SF and many other companies. Red or yellow are the only colours found; red is often used for main line switches, and yellow for yard switches, but sometimes no distinction is made and one colour is used for both. In block signal territory, switch stands did not carry lamps, to avoid confusion with signals. These switches were, of course, protected by the nearby signals, which went to Stop when the switch was open. Outside block signal territory on main lines, lamps (or reflectors) were always used. Ideally, the lamp should be at the engineman's eye level, 10 to 11 ft above the rail, but were usually somewhat lower, 7 to 8 ft. This is high enough to avoid confusion with hand signal lamps. A low lamp was at a height of 4 to 5 ft. The disc target is typically 18" in diameter, which gives an idea of the usual size of targets. The operating handle is 22" long. The crank at the bottom is 3-11/16" long, giving a throw of 5-1/4", slightly greater than the point throw to provide extra pressure. Very often yard switches had at most a lamp, often without coloured targets, to show the state of the switches by night. By day, crews were expected to observe the points. Sometimes, small targets were provided on the lamp axis if the lamps did not have them surrounding the lights. Often, yard switches are found with no lamps or targets at all. Interlocked switches never had targets. The figure also shows the German switch indicators. They are black boxes illuminated from inside. The white areas are translucent. When approaching a switch from the facing direction, the arrow shows whether the divergence is to the right or left. When trailing into a switch, the disc is shown when the switch is set for divergence. If set for straight through, then the vertical rectangle is seen as in the facing direction. The discs with sickle-shaped black lines are used when both directions are divergences. In the facing direction, the inclined rectangles are used. Indicators of this type are very widely used in Europe. The same indicators may be found in Austria and Switzerland, while similar ones are used in Belgium and France. German-type indicators have the advantage that they cannot be confused with coloured signal lights.
Figure 153: Switch Targets
Page 96 of 259
Above are shown typical main line switch targets and lamps. These examples are from the Pennsylvania Railroad, the Southern Railway and the Louisville and Nashville, all of which use the original signal colours red and white, and which give a positive indication of a closed switch. (The PRR, SOU and C&EI used white and yellow targets for yard switches). The red pierced "spectacle" is a very early and familiar shape often found on switch targets. Note the green reflective disc. This red spectacle and white inclined bar is familiar, often without the green reflector. There has been a very great variety of target shapes and colours. It is good practice to make the two targets for the straight and diverging routes of different shapes, as is clearly done here, but very often only a single target is used. Different shapes are more easily recognized than the colours under bad illumination. The use of reflective surfaces is a very good idea. With bright headlights, reflective surfaces can replace active illumination with considerable economy, since no maintenance is required.
Figure 154: Targets used by the Denver & Rio Grande Western
Above are some targets used by the Denver & Rio Grande Western. The yellow targets, on high stands, were used in Salida Yard, for example. Yellow and green circular targets also were used on switch lamps. The D&SL targets were at Utah Junction in 1947, while the small red target was seen at Craig much later. Green (or blue) is a relatively bad colour for painting any sign or signal, since it is obscure and does not stand out against the usual backgrounds. When back-lighted, or in the shadows, it becomes black. White, red and yellow are excellent colours, and black makes a good contrast with yellow and white, as does white with red.
Figure 155: Positive “closed” aspect
Two sets of targets showing a positive "closed" aspect are shown above. The Milwaukee arrow-feather target was often used alone, without the green diamond, which seems to have been an afterthought. The feather target is 2' 9" high and 1' 0" wide, the top at a height of 6' 9". The white bar and red arrow is typical of many other targets, both high and low. There may well be alternative colours, such as a white bar and a yellow arrow, and a white disc substitute for the bar. The CB&Q also used small rectangular targets on low switch stands, green above and yellow below, as well as green and yellow lamp surrounds, and the red bar for high signals. The Michigan Central made typical choices for switch target colors, as shown below. A yard switch set for the lead (the track from which others diverge) shows a lunar white light.
Page 97 of 259
Figure 156: Michigan Central Switch Targets
The switch stand may be located on either side of the turnout, usually on two long (15 ft) crossties, called the headblock. The origin of the term "headblock" is probably interesting, but I do not know it. It probably comes from the days of bar rail wooden track, and refers to the base on which the switch rails moved. On a ladder track, the switch stands should be on the outside, across from the body tracks, so that the switch tender will not have to cross tracks to go from one turnout to another. In other cases, the switch stand is generally placed on the right-hand side as seen when approaching the points, if space is available. Oil lamps gave good service in switch lamps for many years, especially when mineral oils (kerosene) replaced organic oils. Their principal disadvantage was the cost of maintenance. The reservoir (fount) had to be filled, and the wicks trimmed or replaced, at regular intervals. Founts and burners could be exchanged as a unit without disturbing the whole lamp, so the maintenance could be performed in the lamp shed. The simple roundor flat-wick burners screwed or socketed into the tops of the founts. An American long-burning lamp could burn for 6 or 7 days, but was not very bright. A 4-day fount held 37.4 cu. in., while a 7-day fount held 63.9 cu. in. A quart of kerosene will burn for about six days in a long-time burner. At this burning rate, the lamps would do well to produce 1 cp. In Europe, propane lamps, using incandescent mantles, gave excellent service. Some could burn for six weeks before the gas tank had to be exchanged. Propane lights never were used in the United States. Electric lamps were excellent, of course, but involved the problem of electricity supply, which could involve a tangle of wires. Electric switch lamps are easily identified by the lack of a chimney and lamp handle. The reliability of oil lamps, and the absence of wires, were strong incentives for retaining them. The short focal length lenses were Fresnel lenses to reduce their thickness, and the glass was appropriately coloured. Optical systems were, in general, crude. Reflectorized surfaces ("Scotchlite") are also an excellent idea where headlights are bright, and should have been used more widely. A split switch may be run through safely in the trailing direction even if the points are set incorrectly. However, if the operating connection is rigid, this will in general break it and free the switch rails. Therefore, the switch rails must be spiked in position until repairs can be made. Also, the train must not be backed once any portion has run through the switch in this way. A spring may prevent breakage of the operating rod, but in general springs are avoided except for turnouts meant to be run through, called spring switches. In this case, a dashpot retards the switch rails from moving back rapidly once they have been forced aside by a wheel. It is very important not to make a partial movement through a spring switch. In general, an accompanying signal shows when the switch rails are in the correct position for a facing movement. Spring switches are very convenient at the exit end of sidings.
Figure 157: Grafik_weichensignal
Page 98 of 259
Figure 158: Switch Stand
Figure 159: Switch Stand
Page 99 of 259
Figure 160: Switch Stand
Figure 161: Switch Stand
Page 100 of 259
Figure 162: Switch Stand
Page 101 of 259
Figure 163: The mechanism used in a switch stand. The two points are locked together with a bar between them. This bar continues to the lever on the near side of the tracks which is used to throw the switch (North American usage). This is an example of a low switch stand, used at locations where there is not sufficient clearance for a tall switch stand. This particular stand is designed to be trailed through by rolling stock, which will cause the points to become lined for the route that the wheels have passed through. It has a reflectorised target.
Figure 164: A manual lock (type HV73) of a point at the railway station of Kinding, Nürnberg–Ingolstadt high-speed railway line.
Page 102 of 259
Figure 165: A ground-frame with a few hand-operated point levers for manually operating nearby points at Bristol Temple Meads.
Figure 166: Hand-operated crank-type points-machine at Sukeva, Finland
Page 103 of 259
Figure 167: Hand-operated point levers at the now defunct Wakayanagi station, Japan
Figure 168: Switch Reversing Lever
Page 104 of 259
Figure 169: Switch Reversing Lever
Figure 170: Retired old switches of the station of The Palms, after their remodelling.
Page 105 of 259
Figure 171: Switch Reversing Lever
Figure 172: Typical Spanish switches with switch reversing levers and switchpoint lamps on sidetracks
Page 106 of 259
Figure 173: Typical Spanish switches with switch reversing levers and switchpoint lamps on sidetracks
Figure 174: Switch Reversing Lever
Page 107 of 259
Figure 175: Davle, the Czech Republic
Figure 176: Manual point lever
Page 108 of 259
Figure 177: Onda Point Machine
Figure 178: Switch Reversing Lever
Page 109 of 259
Figure 179: Switch Reversing Lever
5.1.3.7
Switch Motor / Point Machine
A switch motor (also known as a switch machine or point machine) is an electric or hydraulic or pneumatic mechanism that aligns the points with one of the possible routes. The switch motor also includes electrical contacts to detect that the switch has completely set and locked. If the switch fails to do this, signals are kept at red. There is also usually some kind of manual handle for operating the switch in emergencies, such as power failures. The blades of a turnout are normally moved remotely using an electrically operated point machine. The machine contains the contacts, which confirm the points are moved and locked in the correct position for the route set. Point machines are normally located to one side of the track but a new generation of machines is now appearing where the mechanism is contained in a sleeper fitting between the rails. In some parts of the US, electro-pneumatic point machines are used. They are referred to as switch motors. The London Underground also used electro-pneumatic motors. They require an air main to be laid alongside the track and compressors to supply the air. They can also cause problems with condensation due to climatic changes. This photo shows a heater used to keep the turnout blades free of ice and snow during bad weather. The operations of one of the vital subsystems of Indian Railways (IR) signalling called a point-and-point machine, which guides a train in changing its direction of movement from one track to another, are affected by a number of problems in relation to its intensity of use, repair and maintenance, and environmental stress. A reliability analysis of a point-and-point machine of the Indian railway signalling system was recently carried out. In this analysis, the reliability modelling of a point-and-point machine was elaborately described taking into account the effect of the problems on its operational efficiency. It was observed that even when de-rating the system specifications (i.e. lowering the speed of the train), the reliability of the point-and-point machine system has been poor (0.44 after 1100 days of continuous operation) with existing preventive and corrective measures. Two graphical methods, namely, Nelson-Aalen and total-time-on-test plots, are used to analyse the trend of the failure time data for a set of representative point-and-point machines in the Kharagpur Division of IR. The parametric model as recommended for estimating the reliability of the point-and-point machine is capable of correctly predicting its failure rate probability. The analysis of data obtained from a homogeneous Poisson process of the point-and-point machine system also leads to a better assessment of the reliability pattern with which the problems as mentioned above may be adequately and properly addressed.
Page 110 of 259
Figure 180: Railway turnout with electric point machine
Figure 181: An electric switch motor and associated mechanism used to operate this switch. A closeup of the converging points immediately north of w:Filton Abbey Wood railway station. In this configuration the track is set for trains from Bristol Parkway. The machine itself is a HW type, fitted to the rails with relatively modern adjustable stretcher bars and supplementary detection.
Page 111 of 259
Figure 182: An electric switch motor and associated mechanism used to operate this switch. A closeup of the converging points immediately north of w:Filton Abbey Wood railway station. In this configuration the track is set for trains from w:South Wales or Avonmouth via Brentry
Figure 183: RENFE Motor Points in VIGO Station
Page 112 of 259
Figure 184: An electric point machine located adjacent to the switch blades it operates. Most point machines are electrically operated though London Underground still has a large number of air operated machines.
Figure 185: Automatic Switch Drive
Page 113 of 259
Figure 186: Automatic Switch Drive
Page 114 of 259
Figure 187: Switch Reversing Lever
Figure 188: Switch Reversing Lever
Page 115 of 259
Figure 189: US turnout showing the electro-pneumatic motor to operate the switchblades and the point heater tube alongside the stock rail. Heaters are invaluable in cold weather conditions and are widely used. Turnout motors are usually electric but electro-pneumatic motors are seen in the US and are standard equipment for London Underground.
Figure 190: "Serna" junction station turnout (Salamanca) (separation point of railway lines to Fuentes de oñoro and Plasencia. Salamanca)
Page 116 of 259
Figure 191: "Serna" junction station turnout (Salamanca) (separation point of railway lines to Fuentes de oñoro and Plasencia. Salamanca)
Figure 192: AZP Praha EP 600 electronic point machine
Page 117 of 259
Figure 193: EP 600 electronic point machine hollow sleeper
Figure 194: Fixing the point machine in the hollow sleeper
Page 118 of 259
5.1.4 5.1.4.1
Operation Facing and Trailing
Introduction A set of "facing" points is where, as viewed from the driver's window, there are two potential routes, one straight, the "main", and one curved, the "branch". They are used to divert the train to another track that it enters by means of a matching set of "trailing" points. A train approaching from the other direction on the opposite track encounters the other set of points in the pair, which to it is "facing". Switches are referred to as "facing" or "trailing". This refers to the direction the train travels over the switch. When an approaching train crosses the points first before the frog (i.e. diverging), the point is called a facing point because in this direction, the switch determines which direction the train goes. When a train passes over the frog first before it touches the points (merging), it’s called a trailing point. Travelling in this direction, the switch brings the train into a single track, the points merely allowing the transition. As we can see, whether a turnout is facing or trailing depends on the direction of the train. Facing and trailing are therefore terms used to describe railway turnouts (or 'points' in the UK) in respect to whether they are divergent or convergent. When a train traverses a turnout in a facing direction, it may diverge onto either of the two routes. When travelled in a trailing direction, the two routes converge onto each other. Fixed diamond crossings (with no moving parts) count as trailing points in both directions, although in very exceptional circumstances such as propelling a train in reverse they can derail wagons as they bunch up. Switch(ed) diamonds which contain two stub turnouts in disguise count as facing turnouts in both directions and are also known as moveable angles. Double junctions are now configurable in a number of different ways, whereby the number of facing and trailing turnouts vary.
Figure 195: Facing & Trailing
In the early history of railways in Britain, when signalling and interlocking were primitive, and staff were inexperienced, facing turnouts were a hazard, because they could switch a train travelling at high speed into a slow speed divergence or dead end. Facing turnouts were therefore banned, except when absolutely necessary. Facing turnouts cannot be avoided on single lines and their crossing loops. With the widespread availability of electrically interlocked signalling in modern times, the rule against facing turnouts has been relaxed.
Illustrated working
Figure 196: Animated diagram of a right-hand railroad switch, rail track A divides into two: track B (the straight track) and track C (the diverging track)
Page 119 of 259
In the illustration above, rail track A divides into two tracks: B (the straight track) and C (the diverging track). Each switch contains a pair of linked tapering rails known as points (point blades). These can be moved laterally into one of two positions, determining whether a train coming from A will be led towards B or C. This is known as a facing-point movement. A train coming from B or C will be led to A regardless of the position of the points, as the vehicle’s wheel will force the points to the proper position. Passage in this direction through a switch is known as a trailing-point movement. A switch can be described by the direction in which the diverging track leaves the straight track. A right-hand switch has track C to the right of a straight track formed by A and B. A left-hand switch has track C to the left. A switch can also be symmetrical, or have the two tracks curved at different radii in the same or different directions.
Operation A railroad car’s wheels are guided along the tracks by coning of the wheels. Only in extreme cases does it rely on the flanges located on the insides of the wheels. When the wheels reach the switch, they are guided along the route determined by which of the two points is connected to the track facing the switch. In the illustration below, if the right point is connected, the right wheel’s flange will be guided along the rail of that point, so the train will continue along the straight track (the red track is the track travelled by the wheels). If the left point is connected, the left wheel’s flange will be guided along the rail of that point, and the train will diverge to the right (the red track is the one travelled during a facing-point movement). Only one of the points may be connected to the facing track at any time; the two points are mechanically locked together to ensure that this is always the case. A mechanism is provided to move the points from one position to the other (change the points). Historically, this would require a lever / ground frame to be moved by a human operator, and some switches are still controlled in this way. However, most are now operated by a remotely controlled electric motor or by pneumatic or hydraulic actuation.
Figure 197: The operation of a railroad switch.
Facing turnouts Points can be moved laterally into one of two positions so as to determine whether a train coming from the narrow end will be led towards the straight path or towards the diverging path. A train moving from the narrow end towards the point blades is said to be executing a facing-point movement. A train approaching a facing turnout means it is travelling in a direction facing the points and is able to take either route, hence the facing direction is always the one in which the train has a choice of routes. However there is always a danger of a misplaced switch at a facing turnout, since the safe speed for a divergence is usually much lower than for the straight route. Facing points, if set to divert the train and if approached with speed, would lead to a derailment. The use of facing points should be avoided on a track carrying high-speed traffic. Facing turnouts are necessary at junctions, but have been strongly deprecated on double-tracked railways. Early railways avoided them altogether on main lines. Facing points were the first points of danger protected by fixed signals.
Trailing turnouts Unless the switch is locked, a train coming from either of the converging directs will pass through the points onto the narrow end, regardless of the position of the points, as the vehicle's wheels will force the points to move. Passage through a switch in this direction is known as a trailing-point movement. Trailing points are far safer - if they are left in the wrong position, the flanges on the wheels of the train push the point blades to their correct position and the train stays on the track. Trailing-point switches are less prone to cause derailments because the wheels never have to "choose" a path - they're simply guided through on one set of rails. But to use them to run on the opposite track when the normal track is closed for maintenance, trains have to stop and reverse which adds to the delays already present with single-line working.
Page 120 of 259
A trailing crossover permits a train to "shunt" by backing through the crossover onto a parallel track. With short trains, this is quite practical, but with today's long freight trains is impossibly inconvenient. In a trailing-point movement, the wheels will force the points to the proper position. This is sometimes known as running through the switch. If the points are rigidly connected to the switch control mechanism, the control mechanism’s linkages may be bent, requiring repair before the switch is again usable. For this reason, switches are normally set to the proper position before performing a trailing-point movement. An example of mechanism that would require repair after a run-through in the trailing direction is a clamp-lock. This mechanism is popular in the UK, but the damage caused is common to most types of switches. However, some switches are designed to be forced to the proper position without damage. Examples include variable switches, spring switches, and weighted switches.
Handedness A switch generally has a straight "through" track (such as the main-line) and a diverging route. The handedness of the installation is described by the side that the diverging track leaves. Right-hand switches have a diverging path to the right of the straight track, when coming from the narrow end and a left-handed switch has the diverging track leaving to the opposite side. A straight track is not always present; for example, both tracks may curve, one to the left and one to the right (see Wye switch, below) or both tracks may curve, with differing radii, in the same direction.
Open and Closed The position of a turnout is often described by the terms "open" and "closed." A closed turnout is set for the normal route usually the straight one (perhaps meaning that turning out of the normal main route is closed or prohibited), while an open turnout is set for the diverging route (perhaps meaning it is allowed to turn out from the main route onto the diverging route). Operating a switch to one position or the other is called "lining" it.
Figure 198: Switch Right
Figure 199: Switch Left
Figure 200: Switch Right
Figure 201: Switch Left
Page 121 of 259
Figure 202: Switch Right – Check Rail
Figure 203: Switch Left – Check Rail
Figure 204: Switch Right
Figure 205: Switch Left
Figure 206: Switch Right
Figure 207: Switch Right
Figure 208: Switch Left
Figure 209: Switch Left
Page 122 of 259
Figure 210: A right-hand railroad switch in Oulu, Finland. The facing points are set to divert. From the opposite direction they would be trailing points.
Figure 211: A left-hand railroad switch
Page 123 of 259
Figure 212: Trailing Point Movement
Figure 213: A left-hand railroad switch
Page 124 of 259
5.1.4.2
Operation in cold conditions
In cold conditions, snow and ice can prevent the correct operation of switches. In the past, people were employed by railway companies to keep the switches clear by sweeping the snow away. Some were provided with gas torches for melting ice. More recently, switches have had heaters installed in the vicinity of the points so that the temperature of the rails in these areas can be kept above freezing. The heaters may be powered by gas or electricity.
Figure 214: Self-Regulating Switchpoint Rail Heaters
Figure 215: Gas heating keeps a switch free from snow and ice.
Page 125 of 259
Figure 216: Benicassim's station, works to install a leak in the exit towards Castellon.
Page 126 of 259
Figure 217: Benicassim's station, leak already installed in the exit towards Castellon (still is not operative for the lack of the Catenary)
Page 127 of 259
Figure 218: Benicassim's station, leak already installed in the exit towards Castellon (still is not operative for the lack of the Catenary)
Page 128 of 259
5.1.5 5.1.5.1
Types of Turnouts Overview
The kind of switch used characterises most kinds of turnouts. A very effective switch, first developed for steam railways, was one in which the straight and diverging tracks were completely separate and side-by-side. A length of rail called the switch rail was not spiked down but slid transversely on support plates, so that it could register with one track or the other. The throw of the switch was about 5 inches, usually with stops on both sides to ensure proper registration. In America, this kind of switch was called a stub switch. It also offered the advantage of an easy way to make a three-way switch. Unlike other kinds of switches, ice and snow, odd stones or other extraneous materials cannot get in the way of a proper alignment. For this reason, it was adopted as a safety measure, for example on the London and Birmingham Railway, as well as on the Pennsylvania Railroad. It was exported to the Continent, to France in particular. An important part of a stub switch was the headshoes, malleable iron castings that received the two stock rails on one side, and had a flat table on the other side for the switch rail, with stops on either side. A stub switch had the disadvantage that a train approaching in the trailing direction on the wrong track would certainly be derailed. A serious accident of this type happened at Rio, Wisconsin on the Chicago, Milwaukee and St. Paul on 28 October 1886, with 17 fatalities (mostly due to the subsequent fire). The Milwaukee Road then removed all stub switches from its main lines. Before 1900 they had vanished from main lines everywhere. In the split switch the outer, or stock, rails are continuous; one remains with the undeviated track, while the other forms part of the deviated track. Switch rails, often called just points, connect one or the other closure rail to the outer rails as necessary, only one switch rail being used for each route. These points are planed down, and are supported laterally continuously by the stock rails, which are often braced outside for added strength against overturning. The switch rails are connected by tie rods, and move together to one side or the other on flat slide plates, by means of the operating rod. The operating rod must provide a means of making small adjustments in its length. At the heels, the switch rails are connected flexibly to the closure rails by joint bars. The standard throw of a split switch is 4-3/4". Despite the danger of some obstruction's getting between the point and its stock rail, presenting the danger of the flange's passing between them and derailing the train, this kind of switch proved the safest in practice and is now universally used. The main track was not continuous, but broken at the point of the switch rail which some engineers objected to. The Wharton switch overcame this objection by leaving the main tracks continuous and complete. To take the turnout, a ramp was brought beside the main track that raised a wheel enough by its tread so that the flange could move across the rail, when the wheel pair is guided to one side. Of course, this was not suitable at full speed, but at low speeds it was not objectionable. These turnouts were intended to be used at spurs, sidings and service tracks where the speed would have been restricted at any rate. Switch rails are usually straight, with AREA standard lengths of 11 ft to 33 ft. The point is planed down to a thickness of 1/4", and is rounded off at the top. The heel distance, the distance between the gauge sides of the switch rail and the stock rail at the heel, is 6.50 in. or 6.25 in. The stock rail is not notched to receive them, but the diverging stock rail is bent at the switch angle. The switch rails are supported by slide plates, and held apart by the head rod at the toe, and 3 or 4 back rods along the length. Rail braces support the stock rails against overturning. The switch angle is the angle between the direction of the straight track and the gauge side of the switch rail. Curved switch rails for high-speed turnouts must be carefully designed and well-supported laterally. A single-tongue switch consists of a switch rail opposite a frog in the other rail that will permit a wheel to pass either way. The wheel is guided by one side or the other of the switch rail. This is an early kind of switch, and was even used on steam railways in some cases, but only when speeds were low. It was much more commonly used on street railways. The curve in the closure rail cannot be super elevated, so it is necessary to restrict the speed to a comfortable level. At such a speed, the shock of the divergence at the switch rails will not be significant. Speed is generally restricted to 15 mph for a No. 8 switch, 20 mph for a No. 12, and 30 mph for a No. 15. No restriction is necessary for a straight-through movement, only for the divergence. No divergence is ever normally negotiated at a speed comparable to the overturning speed on the lead curve. Switch rails can be used without crossings in scale tracks, where the wheels are diverted to "live" rails connected with the scale when the switch is open. When closed, wheels pass on the ordinary track. Single switch rails can also be used in "point derails" to enforce a stop signal. Frogs can be used without switch rails in gauntlet tracks, where two tracks are superimposed without connections where the roadway is of restricted width, as on a narrow bridge.
5.1.5.2
Simple Turnout
A simple turnout is one that branches off one line to right or left from a straight main line. We have dealt with ample descriptions of this early on in the text, with explanations of right-handed and left-handed turnouts.
5.1.5.3
Standard and Special Turnouts
These can be found anywhere but the trend is to make layouts as simple as possible in order to reduce installation and maintenance costs. The more complex layouts are usually only used where space is limited. There are a number of standard and special types of turnouts, as discussed here. More details of such applications of special switches are discussed in the following pages.
Page 129 of 259
Figure 219: Applications of turnouts
Figure 220: Single slip switch
Figure 221: Double slip switch
Figure 180: Diamond Crossing
Figure 180: Y Turnout
Figure 180: Right Hand Turnout
Figure 180: Left Hand Turnout
Figure 180: Three-way switch (slip)
Figure 180: Three-way switch (slip)
The "slip switches" illustrated have their points and closure rails entirely within the crossing, which must be at a small angle (less than about 10°) typical of turnout frogs. They permit a transversal track to connect selectively with the tracks crossed, double slip switches acting as crossovers. They are not used in main tracks, but are common in terminals and yards, where space is at a premium. The obtuse crossings may have movable points, especially when the angle of crossing is small. A "wye" switch is not necessarily used in a wye track, but is so named because the routes diverge as in the letter Y. It can, of course, be used in a symmetrical wye track. The uses of turnouts are wide ranging and cover many variations. Details of a few examples are offered below to show the diversity available. In addition to these "standard" switches, there are special switches used where space is at a premium. A wye switch, as it's name implies, is shaped like the letter "Y." Instead of one leg diverging and the other staying straight, both legs diverge in opposite directions. A curved switch (first picture below) is a switch built on a curve. Typically these are identified in terms of the radii of both curves, such as 4'-6'-radius curved switch in a garden railway. That means the larger radius is 6', while the divergent route peels off at a 4' radius. A three-way switch is essentially a wye switch with a straight track going down the middle (middle photo below). The most confusing piece of switchwork is called a double-slip switch (third photo below). This is where two tracks cross at an angle, but trains are able to either go straight across or move onto the crossing track.
Page 130 of 259
One other kind of switch that's often mentioned-especially in terms of early railroading-is the stub switch. This early form of switch has no points. Instead, the rails leading to the switch are bent to line up with either the main or diverging track. This is where the term "bending the iron" comes from. Crews literally bent the iron rails to line up the switch. The advent of heavier trains and heavier rails brought an end to stub switches, though some examples do survive on preserved railroads, particularly narrow-gauge lines.
Figure 222: On prototype and model railroads alike, curved switches are built where space is at a premium. This dual-gauge (0 and 1 gauge) curved switch is on Marc Horovitz’s Ogden Botanical Railway. Dual-gauge switches are considerably more complex than single-gauge switches, but their operation is identical.
Figure 223: A three-way switch allows trains to go either to the left, right, or straight. Notice there are two sets of points imbedded in this example from Jim Strong’s Woodland Railway
Figure 224: A double-slip switch is perhaps the most complex switch there is. Operationally, it’s four switches in one, each crossing over the other, so that trains can run onto any track.
Page 131 of 259
5.1.5.4
Crossovers
A crossover is a pair of switches that connects two parallel rail tracks, allowing a train on one track to cross over to the other. Like the switches themselves, crossovers can be described as either facing or trailing. When two crossovers are present in opposite directions, one after the other, the four-switch configuration is called a double crossover. Occasionally, space considerations require crossovers for both directions at the same location, and these superimposed formations are termed scissors crossovers. If the crossovers overlap in the shape of the letter X, it is dubbed a ‘scissors crossover or diamond crossover’ in reference to the diamond crossing in the centre. This makes for a very compact track layout at the expense of using a level junction. In a setup where each of the two tracks normally carries trains of only one direction, a crossover can be used either to detour “wrong-rail” around an obstruction or to reverse direction. A crossover can also join two tracks of the same direction, possibly a pair of local and express tracks, and allow trains to switch from one to the other. Basically a scissors crossover consists of four (4) simple turnouts and one (1) diamond crossing. On a crowded system, routine use of crossovers (or switches in general) will reduce throughput, as the switches must be changed for each train. For this reason, on some high-capacity rapid transit systems, crossovers between local and express tracks are not used during normal rush hour service, and service patterns are planned around use of the usually flying junctions at each end of the local express line.
Figure 225: Scissors crossover in CMS (Indian Railways)
Figure 226: Scissors or Diamond Crossover
Page 132 of 259
Figure 227: A scissors crossover: two pairs of switches linking two tracks to each other in both directions
Figure 228: Carlisle railway station
Page 133 of 259
Figure 229: Crossrails at Leeds
Figure 230: Cambridge-longplatform-north-04
Page 134 of 259
Figure 231: Level Junction with Scissors (Diamond) Crossover
Figure 232: Stockport Edgeley with awkward (scissors) crossover in foreground.
Page 135 of 259
Figure 233: Crossrails at Leeds
Page 136 of 259
Figure 234: Scissors crossover – fully welded construction
Page 137 of 259
5.1.5.5
Double slip
Figure 235: A double slip switch at Munich Central
Page 138 of 259
Figure 236: A double slip switch
A double slip switch (double slip) is a diamond crossing with crossover on both sides. It is appropriate to use where area is too narrow for scissors crossings. A narrow-angled diagonal flat crossing of two lines combines with four pairs of points in such a way as to allow vehicles to change from one straight track to the other, as well as going straight across. A train approaching the arrangement may leave by either of the two tracks on the opposite side of the crossing. To reach the third possible exit, the train must change tracks on the slip and then reverse. The arrangement gives the possibility of setting four routes, but the four blades at each end of the crossing are often connected to move in unison, so the crossing can be worked by just two levers or point motors. A double slip switch is an acute-angle crossing with four pairs of points making connections within the crossings. The reader should consult a good photograph to understand the layout. On the Great Western Railway, they were known as double compound points, and the connections were slip roads. A train approaching on any of the four tracks may leave on either of the two tracks on the other side of the crossing. The saving in space is considerable, when compared to a crossing with two connecting tracks and four ordinary turnouts. These switches are generally found in stations, where space is at a premium. A simpler version has only two sets of points, and is called a single slip switch. In this arrangment, only trains entering on two of the tracks may choose their routes. The two middle crossings must be self-guarded or movable-nose, since there is no room for guard rails. The two end crossings may be normal ones, with guard rails. The double slip switch occupies no more room than the crossing itself would. Four switch stands or switch motors could be required, but it is possible to connect the points so that only two are required. Indeed, if the pairs of points at each end are connected by a mechanism giving opposite movements, such as a T-lever, only one control is required. In one setting, the direct routes are selected, while in the other the diverging routes are. This I'll call the English connection, since it was the first used, in the 1880's, in the double slip switches supplied to Continental railways. This connection is illustrated in the diagram below. The small arrows show the positions of the points. In manual signalling, this is a very heavy pull, with eight points on one lever.
Figure 237: A double slip switch – “English” Connection
Page 139 of 259
A simpler connection with fewer parts and less lost motion connects the four points at each end so that they move together. Two controls are now required, so there are four possibilities to select the four routes. This is illustrated in the diagram below. The indicator shown is the Cauer, introduced by the Deutsche Reichsbahn, and is the one now in use there and in Austria. Note that when one straight-through route is selected, the other cannot be used. It is clear that two routes can never be simultaneously used in any case. In the United States, two ordinary switch stands were used, and so the aspects of their targets could not be easily correlated with the route set.
Figure 238: Double slip switch with Cauer Indicator
Slip switches are used in station throats and yards, by trains moving at moderate or slow speeds, and seldom in main tracks. They are particularly useful for a diagonal track crossing others, allowing access to each track crossed. Other space-saving trackwork includes scissor crossovers and threeway switches. The design of a slip switch is illustrated below. The frog angle F determines the distance AD, within which half of the slip track must fit. A No. 8 frog gives F = 7.153° and so AD = 37.8 ft for standard gauge, g = 4.7083 ft. The length L of the switch rail is then chosen, which determines S, the heel distance being standard. The point of the switch rail lies a distance m from the point of the frog. An 11-ft. switch rail, and a clearance distance m of 5 ft, leaves a distance 21.7 ft for half the closure rail. This distance is found as shown, first subtracting m, then finding the side BE of the triangle DBE (neglecting the point thickness), and finally subtracting L. BE is usually not much different from BD. Now the radius of the closure rail can be found, which is 1437 ft. in this case. We see that a slip switch is practical for a No. 8 frog. When the frog angle is small enough that F = 2S, the closure rail becomes straight. To construct the slip switch, the locations of the frog points are marked. Then the switch rails can be located and installed, and finally the closure rail can be laid. The switch and closure rails for the other side have not been shown, but are found the same way.
Figure 239: Slip switch
Page 140 of 259
In North America, the arrangement may also be called a double switch, or more colloquially, a puzzle switch. The Great Western Railway in the United Kingdom used the term double compound points, and the switch is also known as a double compound in Victoria (Australia).
Figure 240: Junction south of Wilkinson Street tram stop
Above is the junction south of Wilkinson Street tram stop, visible in the middle distance, that gives access to the Nottingham Express Transit (NET) tram depot for northbound trams. Through the Hyson Green area of the city, the northbound and southbound routes follow different streets. As the northbound route is to the east of the southbound this entails right-hand running, unlike the left-hand running that is common to the rest of the system. The crossing in the foreground is the northern switch point. The 10 in a diamond sign on the left indicates the maximum speed for trams heading to the depot is 10km/h. Below is a diagrammatic representation of how a double slip switch works.
Figure 241: Double slip switch operation
Page 141 of 259
Figure 242: Double slip switches
Figure 243: A double slip switch at a factory
Page 142 of 259
Figure 244: A double slip switch at a factory
Page 143 of 259
5.1.5.6
Single slip
A single slip switch works on the same principle as a double slip but provides for only one switching possibility. Trains approaching on one of the two crossing tracks can either continue over the crossing, or switch tracks to the other line. However, trains from the other track can only continue over the crossing, and cannot switch tracks. This is normally used to allow access to sidings and improve safety by avoiding having switchblades facing the usual direction of traffic.
Figure 245: A single slip switch
Page 144 of 259
Figure 246: A single slip switch
5.1.5.7
Outside slip
An outside slip switch is similar to both the double and single slips, but the switchblades are not contained wholly within the diamond.
Figure 247: A double, outside slip in Heidelberg main station
Page 145 of 259
5.1.5.8
Stub switch
Figure 248: A Narrow Gauge Stub-Switch
A stub switch lacks the tapered points (point blades) of a typical switch. Instead, both the movable rails and the ends of the rails of the diverging routes have their ends cut off square. The switch mechanism aligns the movable rails with the rails of one of the diverging routes. The rails leading up to a stub switch are not secured to the sleepers for several feet, and rail alignment across the gap is not positively enforced. Stub switches also require some flexibility in the rails, or an extra joint at which they hinge. Therefore these switches cannot be traversed at high speed or by heavy traffic and so are not suitable for main line use. A further disadvantage is that a stub switch being approached from the diverging route that is not connected by the points would result in a derailment. Stub switches were more common in the very early days of railways and their tramway predecessors. Now, because of their disadvantages, stub switches are used primarily on narrow gauge lines and branch lines. Some modern monorail switches use the same principle.
Figure 249: Stub Switch
Page 146 of 259
5.1.5.9
Plate switch
Figure 250: A Narrow Gauge Plate Switch
A plate switch incorporates the tapered points of a typical switch into a self-contained plate. Each point blade is moved separately by hand. Plate switches are only used for double-flanged wheels, with wheels running through the plates on their flanges, guided by the edges of the plate and the moveable blade. Because plate switches can only be used by double-flanged wheels and at extremely low speeds, they are typically only found on hand-worked narrow gauge lines.
5.1.5.10 Three-way switch
Figure 251: A three-way stub switch at Sheepscot station on the Wiscasset, Waterville and Farmington Railway
Page 147 of 259
A three-way switch is used to split a railroad track into three divergent paths rather than the more usual two. The complexity of such arrangements usually results in severe speed restrictions, and therefore three-way switches are usually only used in a station or depot where space is restricted and low speeds are normal.
Figure 252: A three-way switch formerly at Brisbane's Light Street tram depot now on display at the Brisbane Tramway Museum
Stub switches can more readily select between three routes, so most three-way switches are stub switches, although some were built using points. It was extremely difficult to hold the two rails the correct distance apart for the length of the switch with these types of switch. A three-way switch from a Brisbane tram depot is shown above. This example has two points (point blades) on each track, allowing for three diverging routes. The points can both be set to one side, resulting in a vehicle turning off the straight track. Alternatively, the two blades can be separated if the vehicle must continue along the straight track. A picture of a three-way stub switch can be seen here.
Figure 253: Three-way Stub Switch
Page 148 of 259
5.1.5.11 Interlaced turnout
Figure 254: Interlaced Turnout
An interlaced turnout is a different method of splitting a track into three divergent paths. It is an arrangement of two standard turnouts, one left- and one right-handed, in an “interlaced” fashion. The points of the second turnout are positioned between the points and the frog of the first turnout. In common with other forms of three way turnouts an additional common-crossing is required. Due to the inherent complexity of the arrangement, interlaced turnouts are normally only used in locations where space is exceptionally tight, such as station throats or industrial areas within large cities.
5.1.5.12 Gantlet (Gauntlet) Track A gantlet (or gauntlet) track refers to the situation where railway tracks converge onto a single roadbed and are interlaced to pass through a narrow passage such as a cutting, bridge, or tunnel. A switch frog at each end allows the two tracks to overlap, and the four rails run parallel through the passage on the same crossties and separate again at the other end.
Figure 255: Gantlet Track
Page 149 of 259
Figure 256: Gantlet Track
Usage and Origins Gantlet tracks are commonly used when a rail line's capacity is increased with the addition of an additional track, but cost or other factors prevent the widening of the bridges. They are particularly used in funiculars where there is limited width for a complete four-rail system or a desire to hold down the costs of a full four-rail system, as seen in the photo to the right, Angels Flight, Los Angeles. Since there are no points or other moving parts in a gantlet track, a train operating on one of the tracks cannot be routed onto the other. Because two trains cannot use the gantlet at the same time, scheduling and block signals must allow for this restriction. The term is derived not from gauntlet meaning a type of glove, but from the expression running the gauntlet, which means running between two confining rows of adversaries. A gantlet track can also be used to move a switch away from a heavily trafficked road, as used on the Mannheim tram system. An alternative arrangement is to use three rails (dual gauge), with the two tracks sharing the middle rail. Gantlet track is typically used for short stretches of track where it is cheaper to provide extra rails than to provide switches and reduce the line to single track.
Passing Track The originator of the passing track was Prof. Thaddeus Lowe with his Mount Lowe Railway in Altadena, California (1893 - 1938). In an attempt to negotiate the steep climb of Mount Echo, Lowe was informed by his chief engineer David Macpherson that the grading required to accommodate the usual four rails would be extensive and costly. Most of the concern was caused by a large granite chasm that would require extensive backfilling and shoring. Overnight Lowe came up with a three-rail configuration that employed four rails only at the dead centre or passing section of the funicular. This configuration became a world wide standard for funicular railways.
Examples worldwide
America A gantlet track can also be used when two railroads of different gauges share right-of-way; the standard-gauge Delaware, Lackawanna and Western Railroad used the wide-gauge Erie Railroad's tunnel through the New Jersey Palisades in this way before the DL&W built its own tunnel. The DL&W also used a gantlet track arrangement to allow two sets of track of the same gauge to pass through the Oxford Tunnel in Oxford, New Jersey. In this latter arrangement, the tracks overlapped within the tunnel, without the use of switches, so that the tracks travelled down the centre of the tunnel where the overhead clearance was greater. The disadvantage of such an arrangement is that the tunnel has, in effect, only single-track capacity. On low-density traffic lines, such an arrangement would probably not be problematic, although higher density use could cause delays.
Page 150 of 259
Australia The Como River Bridge was built as single line in the 1880's. The line was duplicated soon after, except for the bridge. The bridge was fitted with a gantlet track, which needs no turnouts, and hence needs no signal box at the far end. The bridge was replaced with a double track bridge around 1973. Another example is visible in the tunnel under George Street, Railway Square, at part of the spur which leads from the connection between Sydney's intercity terminus and Redfern. This particular example was formerly a 4-track tunnel but became a gantlet track when the structure gauge was increased to accommodate CityRail's double-decker carriages. A single track continues on to the PowerHouse Museum and can be visited as part of the Ultimo Pedestrian Network. This track formerly served the Darling Harbour goods yards and was disconnected from rest of the corridor when it formed part of the Sydney Light Rail network.
Canada A four rail gantlet track still exists on the Canadian Pacific Railway Bridge across the Rivière des Prairies between Montréal and Laval because the structure gauge is not sufficiently wide for a regular double track. This bridge is used by freight trains of the Canadian Pacific Railway (CPR), the Chemins de Fer Québec-Gatineau (CFQG) (or the Quebec Gatineau Railway (QGR)) and by the Blainville-Saint-Jerome Line suburban trains of the Agence métropolitaine de transport (Metropolitan Transportation Agency)
Germany In Mannheim, a gantlet track is used to shift the switch out of the road to prevent the switch from being driven over by cars and trucks. Mannheim also uses a gantlet track to run trams within less space.
The Netherlands Because of space constraints, Amsterdam's tram network uses gantlet track for two main routes through small streets in the city centre, and on one line gantlet tracks are used to make room for platforms at a tram stop.
Figure 257: Passing Track
Portugal The Lisbon tram system interlaces to negotiate one particularly narrow corner in Alfama.
United Kingdom In Britain gauntleted track is frequently called interlaced track and was often used where street tramways had to pass through narrow streets and even archways in ancient city walls. Two modern examples of short sections of interlaced track are to be found on the Tramlink system in South London. One of these examples is a conventional use where a short obstruction prevents two tracks being laid side by side. The other is rather more unusual as it is not strictly necessary but done to avoid a set of points being located in the middle of a traffic junction as this would cause maintenance problems. Another example of interlaced track is found on the Nottingham Express Transit system just north of the The Forest tram stop—again, to move points off the road junction itself.
Page 151 of 259
5.1.5.13 Wye switch
Figure 258: Wye Switch
Figure 259: Sefton Station: Double track triangle, drawn in one-rail style
Figure 260: A Wye.One approach to this wye has been abandoned, but it and the two remaining legs are still visible.
Figure 261: Wye Switch – Symmetrically diverging
A Wye in North American railroad terminology, known as a triangle in English language terminology outside North America, is a triangular shaped arrangement of tracks with a switch at each corner. With a sufficiently long track leading away from each corner, a train of any length can be turned. A Wye switch has trailing ends which diverge symmetrically and in opposite directions. Their name originates from the similarity of their shape to that of the letter Y. Wye switches are usually used where space is at a premium. In North America this is also called an "Equilateral Switch" or "Equilateral Turnout".
Overview Turning is required for any directional piece of railroad equipment, such as most steam locomotives, or indeed many passenger trains, especially those that have a dedicated tail end car such as an observation car. Individual locomotives and railroad cars can be turned on a turntable, but whole trains cannot. A wye or loop are the only ways of doing that. Railroads in North America have more wyes than railroads elsewhere, and North American locomotives and cars are much more likely to be directional than those elsewhere. This is due to the fact that in most places in Canada and the United States, the railroad came first, or at least early, and therefore builders had much more freedom to lay down tracks where they wanted. Similarly, at many rural railway locations in Australia, triangles were also used as an alternative to turntables for much the same reason. In Europe, extensive use was made historically of bi-directional tank locomotives and push-pull trains, and more recently most diesel locomotives and electric locomotives ordered in Europe have been fully bi-directional.
Page 152 of 259
Examples Sefton railway station, Sydney, lies on one corner of a triangular junction. The triangle junction allows trains to branch off in either direction, without the need to terminate or change end. One train a day from Birrong to Sefton does terminate at Regents Park station, in order to clean the rust off the crossover rails. There is also a goods branch from Chullora, and a proposed separate single track freight line. The three passenger stations at the vertices of the triangle have island platforms which makes it convenient to change trains. The sharp curves of the triangle and especially the turnouts on those sharp curves restrict train speeds to between 10 km/h and 50 km/h. The Keddie Wye in Keddie, California, was built by the Western Pacific Railroad and is a remarkable engineering feat. Two sides of the wye are built on tall trestles and one side is a tunnel bored through solid rock. There are a number of British examples, including the one known as the Maindee triangle in Newport, South Wales. Here the ex-GWR South Wales mainline from London to Swansea is joined by another GWR line from Shrewsbury via Hereford. The significance of it is that steam-hauled trains can run to Newport and their engines be turned using the triangle. Shrewsbury also has a triangular route formation that was used to turn steam locomotives, and is still available. The earliest British (and possibly worldwide) example is the double-tracked triangle within Earlestown railway station on the Liverpool and Manchester Railway, which was completed by the Grand Junction Railway in 1837. The triangle has two passenger platform faces on each of its three sides and five of the six platforms are in frequent (half-hourly etc) use by passenger trains. When steam engines were in regular use the triangle (which is of course also traversed by freight trains) was also used to turn locomotives and could still be so used.
5.1.5.14 Run-off points Run-off points are used to protect main lines from stray or runaway railroad cars or from trains passing signals set at danger. In these cases, vehicles would otherwise roll onto and obstruct a main line (sometimes known as fouling) and cause an accident. Depending on the situation in which they are used, run-off points are referred to either as trap points or catch points. Derailers are another device used for the same purpose.
5.1.5.15 Trap points
Figure 262: Diagram showing the use of trap points to protect the main line at the exit of a siding
Page 153 of 259
Catch points and trap points are types of turnout which act as railway safety devices. Both work by guiding railway carriages and trucks from a dangerous route onto a separate, safer track. Catch points are used to derail vehicles which are out of control on steep slopes (known as runaways). Trap points are used to protect main railway lines from unauthorised vehicles moving onto them from sidings or branch lines. Either of these track arrangements may lead the vehicles into a sand drag or safety siding, track arrangements which are used to safely stop them after they have left the main tracks. A derail is another device used for the same purposes as catch and trap points. Trap points are found at the exit from a siding or where a secondary track joins a main line or loop line or where a goods line joins a main line that may be used by passenger trains, to protect the main line from a train or vehicles which accidentally pass beyond the limits of the siding. They are normally non-powered trailing points, i.e. they allow a train to pass safely through one direction but will cause the train to be derailed if it passes in the wrong direction. A facing turnout is used to prevent any unauthorised movement that may otherwise obstruct the main line. The trap points also prevent any damage that may be done by a vehicle passing over points not set for traffic joining the main line. In the United Kingdom, the use of trap points at siding exits is required by government legislation. An unauthorised movement may be due to a runaway wagon, or may be a train passing a signal at danger. When a signal controlling passage onto a main line is set to "stop", the trap points are set to derail any vehicle passing that signal. Interlocking is used to make sure that the signal cannot be set to allow passage onto the main line until the trap points have been aligned to ensure this movement can take place. Trap points should preferably be positioned to ensure that any unauthorised vehicle is stopped a safe distance from the main line. However, due to space limitations, it is not always possible to guarantee this. If the lines are track circuited, then a track circuit interrupter will be fitted to one of the run-off rails in order to break the track circuit and set main line signals to 'danger'. Unless they have been specifically set to allow traffic to pass onto the main line, the trap points will direct any approaching vehicle away from the main line. This may simply result in the vehicle being derailed, but in some cases a sand drag is used, especially where the vehicle is likely to be a runaway travelling at speed due to a slope. In the photo shown, the points are provided at the limit of authorised shunting.
Figure 263: Trap Point
Page 154 of 259
Figure 264: Trap Points located to protect a main line track from vehicles moving past the shunt limit board and causing an obstruction. Note the mix of concrete and wooden sleepers.
5.1.5.16 Types of trap points There are several different ways of constructing trap points:
A single tongue trap consists of only one switch rail, leading away from the main line to a short tongue of rail. This is usually placed in the rail furthest from the main line. Double trap points are a full turnout, leading to two tongues. Usually the tongue nearer the main line is longer than the other. Trap points with a crossing are double trap points where the tongues of rail are longer, so that the trap point rail nearest the main line continues over the siding rail with a common crossing or frog. A trap road with stops is a short dead-end siding leading to some method of stopping a vehicle, such as a sand drag or buffer stop. Wide to gauge trap points have switches that work in opposite directions and are therefore either both open or both closed. Vehicles derailed at these points will tend to continue in a forward direction rather than being thrown to one side. Wide to gauge points are typically found on sidings situated between running lines.
The type of trap points to be used depends on factors such as the gradient of the siding, and whether locomotives enter the siding.
Figure 265: A trap point with buffer stops at the train station of Allersberg, Nuremberg-Munich high-speed railway line. This is a safety device that would lead a train to the buffer at the right, in the unlikely event that the engineer passes by the red signal before the switch. Such trap point railway switches are obligatory for high-speed railway lines (v_max > 160 km/h) in Germany.
Page 155 of 259
Figure 266: Double trap points with much longer rails, at Castle Cary railway station. See the two-level baseplates under the rising turnout rail, and also the inner rail stops short of an extended check rail
Figure 267: Double trap points protecting the South Wales Main Line at the exit of Stoke Gifford Rail Yard near Bristol Parkway railway station
Page 156 of 259
5.1.5.17 Catch points
Figure 268: Catch Point
A catch point is a safety device installed at a rail siding to prevent unattended wagons and engines running away uncontrolled onto the main line and causing trouble. It may also be used where a secondary track joins a main line. Catch Points are installed on the running line itself where track follows a rising steep gradient and are provided at the lower end of the gradient, in order to derail (or "catch") runaway vehicles travelling down the gradient and prevent them from colliding with a following train or other equipment (such as level crossing barriers) further down the slope. This may simply be a vehicle that has accidentally been allowed to runaway down the slope, or could be a wagon that has decoupled from its train. In either case, the runaway vehicle could collide with a train further down the slope, causing a serious accident. Runaways may go unnoticed, especially before the days of track circuits, leading to a severe crash involving at worst, a passenger train. It is better to catch the runaways at low speed before they build up speed on a long falling grade, and, occasionally catch points are expanded into a safety siding. Catch points are usually held in the ‘derail’ position by a spring. They can be set to allow a train to pass safely in the downhill direction using a lever or other mechanism to override the spring for a short time. They may consist of a full turnout with two switchblades (rails), or as little as a single switchblade. In some cases, on a track that is only traversed by uphill traffic, trailing point blades are held in a position to derail any vehicle travelling downhill. However, any traffic travelling in the correct (uphill) direction can pass over the turnout safely, pushing the switch blades into the appropriate position. Once the wheels have passed, the catch points are forced back into the derailing position by springs. In these cases, a lever may be provided to temporarily override the catch points and allow safe passage down the gradient in certain controlled circumstances. Catch points originate from the days of the ‘unfitted’ goods train. These trains did not have a mechanism in place to automatically brake runaway cars. Catch points were therefore required to stop the rear portion of a train that had become divided, although they would also stop vehicles that had run away for any other reason. Now that trains are all ‘fitted’, catch points are mostly obsolete. The use of catch points became widespread in the United Kingdom after the Abergele train disaster, where runaway wagons containing paraffin oil (kerosene) collided with an express train. Catch points continued to be used in the UK until the mid-20th Century. At this time, continuous automatic brakes, which automatically stop any vehicles separated from their train, were widely adopted, making catch points largely obsolete.
Page 157 of 259
Safety considerations The catch or trap points should preferably be far enough away from the mainline to ensure that any runaway wagon stops clear of the mainline. It is not always possible to guarantee this, particularly if space is limited. If the line is track circuited, then a track circuit interrupter will be fitted to one of the run-off rails in order to break the track circuit and put main line signals to ‘danger’.
Figure 269: Catch points operation
Figure 270: Catch point at Springwell
Page 158 of 259
Figure 271: Another catch point at Springwell
5.1.5.18 Track Circuit Interrupter A track circuit interrupter may be fitted at catch points, trap points or buffer stops to maintain a track circuit in the 'occupied' state in the event of a derailment. The track circuit remains de-energised until the interrupter is replaced.
Application At catch or trap points
Figure 272: An insulated track circuit interrupter fitted to trap points.
Page 159 of 259
Trap points or catch points are designed to intentionally derail vehicles making an unauthorised movement. When a vehicle derails completely, its wheels cease to shunt the track circuit. Since the vehicle might still be foul of the track, it is important to maintain the track circuit in the 'occupied' state. To achieve this, a cast iron interrupter is fitted to one of the run-off rails such that it will be struck by the wheels of a vehicle that is about to be derailed. Since the track circuit is bonded via the interrupter, it is proved to be intact when the track circuit relay is energised. At buffer stops A track circuit interrupter may be fitted behind a friction buffer stop. In the event of the buffer stop being struck by a train and pushed along, an adjacent line may potentially be fouled. Breaking the interrupter causes the adjacent track circuit to show 'occupied' until the interrupter is replaced.
Insulated and non-insulated interrupters Originally, track circuit interrupters were directly connected to the rail, both physically and electrically. One of the track circuit tail cables would be connected to the interrupter, it being connected to the rail. If the interrupter was broken, it was possible that the broken part, with cable still attached, could drop onto the rail and allow the track circuit to remain energised and show 'clear'. To overcome this, it is now practice for track circuit interrupters to be insulated from the rail to which they are attached. A track circuit cable is taken via the interrupter, with one end connected to the upper part of it and another end to the lower part. The cable is at opposite polarity to the rail, therefore should the broken part of the interrupter drop onto the rail, the track circuit will be short circuited and show 'occupied'.
Provision of Overlaps, Flank Protection and Trapping GK/RT0011 specifies the requirements for the provision of track circuit interrupters. Where vehicles derailed at trap points could foul lines other than the
Diagram In the UK, the interrupter is shown on signal box diagrams as two closed triangles inside the points.
Figure 273: Interrupter drawn as two filled triangles. Assume train has overrun 53 signal and 52A trap points and interrupter shows DBT T.C. on Down Line as blocked (twin red lights)
Accidents Melton Mowbray Rail Accident Report 33 - a track circuit interrupter is fitted to the trap points beyond signal 53 so ... track circuit interrupter and cause signals 51 and 22 if they have been ... [2]
Failure JOINTLESS TRACK CIRCUIT: Mechanical failure of track circuit interrupter. Failure rate:. 4.66E-04. per year per item of equipment. Unavailability:. N/A. per item of equipment ...
Treadles Track circuit interrupters are similar to treadles, the main difference being that interrupters remain open circuit once opened, whereas treadles reclose after activation.
Page 160 of 259
5.1.5.19 Sand drag The catch points may be followed by a sand drag, which can be a siding (sometimes known as a safety siding) covered with sand or just a sand-filled trough. The purpose of the drag is to safely bring the runaway vehicle to a stop from high speed without causing excessive damage. They were typically placed at the bottom of steep hills to catch wagons which had broken away from their train.
Figure 274: Trap points and a sand drag protect the exit of a station passing loop (left), while catch points stop vehicles from running away down a steep slope (right)
Page 161 of 259
5.1.5.20 Arrestor bed An Arrestor Bed or Arrester Bed is an area of special material designed to stop a runaway vehicle. Arrestor beds include:
EMAS crushable concrete used to stop aircraft which overrun a runway. Gravel Runaway truck ramps on highways. Railway safety sidings.
5.1.5.21 Derailers A Derail or Derailer is a device used to prevent fouling of a track by unauthorized movements of trains or unattended rolling stock. It works (as the name suggests) by derailing the equipment if it attempts to roll past the derail. Derails may be applied:
where sidings meet main lines or other through tracks at junctions or other crossings to protect the interlocking against unauthorized movement at an area where crews are working on a rail line (via a portable derail device)
A derailer works by derailing any vehicle passing over it. There are different types of derailer, but in some cases they consist of a single switch point installed in a track. The point can be pulled into a position to derail any equipment that is not supposed to pass. There are two basic forms of derail. The most common North American form is a wedge which fits over the top of the rail. If a car or locomotive attempts to roll over it, the wheel flange is lifted over the rail to the outside, derailing it. When not in use, the derail folds away, leaving the rail unobstructed. It can be manually or remotely operated; in the former case it will have a lock applied to prevent it from being moved by unauthorized personnel. In British and Japanese usage, trap points or catch points are more commonly used than derailers. These are basically a complete or partial railroad switch, which directs the errant trains or cars away from the track. This form is seen in North American as well. The Hayes derail is a movable casting that can be placed on the rail to lift and divert a wheel to the outside of the rail. The opposite wheel, of course, comes off its rail and falls onto the ties. Derails are used to protect the main line from a private siding in case of loose cars on the siding. Lack of a gradient should not be sufficient; cars can be blown by the wind or moved maliciously. It can be operated by an electric switch machine, or manually by a switch stand. On main lines, point derails are used instead; these are turnouts that don't go anywhere. Derails not only forcibly prevent fouling another line, they also give incontrovertible evidence of passing a signal at danger, like a crossing gate or a smashboard. They are encouragement not to overrun a stop signal.
Figure 275: Derailer
Page 162 of 259
Figure 276: Derailer
5.1.5.22 Dual gauge switches
Figure 277: Dual-Gauge Switch
Dual gauge switches are used in dual gauge systems. There are various possible scenarios involving the routes that trains on each gauge may take, including the two gauges separating or one gauge being able to choose between diverging paths and the other not. Because of the extra track involved, dual gauge switches have more points and frogs than their single gauge counterparts. This limits speeds even more than usual.
Page 163 of 259
5.1.6 5.1.6.1
Turnout System Solutions High Speed Turnouts
Figure 278: High Speed Turnout
Generally, switches are designed to be safely traversed at low speed. However, it is possible to modify the more simple types of switch to allow trains to pass at high speed. More complicated switch systems, such as double slips are restricted to low-speed operation. The conventional way to increase turnout speeds is to lengthen the turnout and use a shallower frog angle. If the frog angle is so shallow that a fixed frog cannot support a train’s wheels, a swing nose crossing will be used. Higher speeds are possible without lengthening the turnout by using uniformly curved rail and a very low entry angle. An AREMA (American Railway Engineering & Maintenance of Way Association) design number 20 turnout has a diverging speed limit of 45 mph. High Speed trains require high-speed turnouts. In Japan, the so-called "bullet train" or "Shinkansen" has special routes and trackwork. Turnouts are designed for 160 km/h (100 mi/h) operation. In the example shown here, there are seven point motors to operate the very long and heavy switchblade. Similar turnouts are provided for the TGV high-speed lines in France. Vossloh Cogifer supplied the first material for the South-East TGV (French High-Speed Train System) line in 1980. Vossloh Cogifer’s technology, and in particular the patented monobloc movable crossings and the fully inclined running table mean that trains can run at the highest speeds. In 1991, the Atlantic TGV travelled over Vossloh Cogifer designed and manufactured Points and Crossings at a speed of 501 km/h. Vossloh Cogifer has supplied more than 400 Points and Crossings specifically designed for high-speed train systems throughout the world.
5.1.6.2
Metro and Tram Turnouts
Modern manufacturers offer a complete range of points and crossings systems for all types of steel-wheel or tyred-wheel metros: heavy transit systems, light transit systems, and automatic systems, even with disruption to traffic to a minimum, thus optimising costs. For fully automated, driverless transport systems, special movable switches for route changes are available. The switch points of tramlines are often operated remotely by the driver. Monorail systems have special switches.
Figure 279: Rotary switch in operation at summit station of Pilatus Railway
Page 164 of 259
Figure 280: Voest Alpine Metro and Tram Turnouts
5.1.6.3
Roller coaster switches
Many roller coasters have switches for the siding, or even for a double station system, for example in Disneyland Resort Paris' Space Mountain and Big Thunder Mountain coasters. Regular rail can cross its own track because the gaps in the rails for wheel flanges are narrow, permitting the bladed design in this article. Round pipe roller coaster rails and box beam monorail rails usually have wheels riding at angles other than on top. These additional other angle wheels are a larger loading gauge, requiring big gaps in the rail (structure gauge) where rails cross or meet. There are three basic switch designs for roller coasters. Flexing, substituting and table rotating rails have all been used. Flexing the entire rail truss, fixed at one end, to point towards an alternate destination requires manipulating a long segment of rail. Substituting a segment requires placing two or more segments of rail on flat plate that is moved in its entirety to provide straight or curved track. Alternately these substitution track segments can be wrapped around a rotating cylinder, creating a triangular truss or a two sided plate. Rotating a table with a curved track segment in a Y junction is the less used third option. This can even make a triangle junction. If the curved track turns the cars 60 degrees, and three rail lines meet as three equally spaced spokes, 120 degrees apart, than the curved track sitting on a turn table can be rotated to connect any two of the three rail lines at this junction.
Figure 281: Substitution track switch for rail at Chester Zoo - Switching Section on the Monorail ride.
5.1.6.4
Heavy Haul Turnouts
Figure 282: Heavy Haul turnouts
Page 165 of 259
Fixed crossing
Figure 283: A one-piece cast frog. The shiny line crosses the rusty line. This is an example of North American "self-guarding cast manganese" frog, where guardrails are not used, the raised flanges on the frog bearing on the face of the wheel as it passes through the frog.
The fixed crossing can only be so fine an angle, say 1 in 20, before the wheels start to go the wrong way at the V of the V-crossing. This limits the maximum speed of the crossing. In addition, the gap at a fixed V-crossings are a weak point on the railway line where the heavy wheel must bump across the gap of about 10cm, supported by the wheel flanges, pounding the rail so much that the steel can deform and/or wear away. The damage spreads to other components including the wheels, and the noise can also be a nuisance. Repairing the damage can also be a problem if the railways are busy with trains, and few opportunities exist between trains to do the repairs.
Page 166 of 259
Swingnose Crossing / Moveable Point Frog
Figure 284: VAE crossing with moveable point and manganese base plate
Figure 285: A switched crossing
A swingnose crossing (moveable point frog, switched crossing) is a device used at a railway turnout to eliminate the gap at the common crossing (a.k.a. frog). As the name implies, there is a second set of points located at the frog. This effectively eliminates the gap in the rail that normally occurs at the frog, so long as trains are moving in the direction that the switch is aligned. Two switch machines are required to make a movable point frog switch work. A switched crossing will normally be provided for turnouts with a very acute angle. The crossing will have a powered element, which will be set for the required route at the same time as the switchblade is set.
Figure 286: A moveable point frog (swingnose crossing) The point of the V-shaped rail is moved to align the rail in the appropriate direction where the two rails cross.
Page 167 of 259
Swingnose crossings allow the V-crossing to have as fine an angle as required, allowing for higher speeds. The swingnose crossing also overcomes the weakness of the gap by moving the point of the V-crossing from side to side depending on which way the turnout or switch diamond is set. The wheels are supported the whole way on their treads and do not make the noise and vibration that would otherwise occur. These crossings have flexibly moving point and splice rails. The complete crossing is mounted on a continuous base plate. This guarantees the directional stability of the crossing both during transport and operation. The base plate is a compound comprised of cast manganese and a welded construction, which is bonded together by special welding. This permits continuous wheel overrunning area (no running edges and head surface interruptions), therefore particularly suitable for high-speed and heavy haul traffic as well as for mixed operation (different vehicles and wheel set types). Also, no check rails are required which is a condition for high-speed traffic. There is a reduced airborne and structure-borne noise combined with highest possible service life because there are no impacts in the wheel transition area.
Figure 287: Swingnose crossing operation
Parameters Swingnose crossings would be used for V-crossings finer than about 1 in 20, and for axle loads in excess of 25T. Interlocking Swingnose crossings need to operate at the same time as the turnout switches to which they belong. This may be too stiff for manual operation, and may require power operation. The main turnout end and the swingnose crossing end require separate point motors. Swingnose Crossing vs. Switch Diamonds Swingnose crossings eliminate the gap in the V-crossings (aka frog). Switch diamonds eliminate the gap in the K-crossings.
Thick Web Switches
Figure 288: Thick Web Switches
Switches made from specific asymmetrical tongue rail sections are forged at the end to match the standard rail section. The transition from one section to the other lies mostly in the clamped area at the end of the switch, which makes welding in the flexible area superfluous. The length of the forging can be adjusted to the specific connecting system such as welding, insulated fishplating or emergency fishplating. In order to reduce the setting forces and to influence the elastic line of the switch, it is possible to mill the base in the flexible area. One major advantage is that there are no weld joint in the complete, non-clamped switch area.
Page 168 of 259
Weldable CMS Crossing Weldable CMS crossings are not produced in India. At present CMS Crossings are connected by fish-plated machined joints, as the welding technology of Cast Manganese Steel crossing with normal rails of carbon steel is not available in our country. Fish plated machined constitutes the weak link in the track which leads to less safety and comfort in the track. It also attracts heavy wear and tear also of CMS Crossing. Hence, Indian Railways needs to undertake increased maintenance and has additional down-time of the track. VAE GmbH, Austria is one of the few that has developed this special welding technology and is in course of transferring this technology to VAE VKN in India. It is recommended to use the EDH-process especially also for weldable CMS which will further improve the lifespan and reduce the life-cycle costs.
Trailable Turnouts
Figure 289: Trailable turnout with clamp lock and recoiling cylinder
Figure 290: Self-regulating clamp lock
Trailable turnouts are trailed in operation (cut open) which makes manual setting of the turnout or switch machines obsolete. After the train ran over the turnout, the turnout is re-set automatically into the original position by the resetting device. This is achieved by a spring which acts in a cylinder filled with oil and re-locates the switches via the lock or the operating rods to their original positions. Locks used for trailable turnouts must be trailable. So, for instance, the clamp lock is trailable; it can be set in case of a "wrong passage" from the turnout heel by the wheels of the vehicle and the thus produced switch movement. No damage is done to the switches and the lock elements, provided the speed of the vehicle during this trailing process is relatively low. Trailable turnouts can be operated with a stretcher bar and without a lock. For safety reasons the monitoring and indication of the position of the switches by point detectors (ELP final position detectors) and by light signals is recommended.
Page 169 of 259
Advantages are as follows:
Trains can pass in unmanned stations or on factory tracks without any loss of time (because of manual switching) By retarded re-setting of the switches the wheel-sets of vehicles and the switches of the turnouts are prevented from damage. In addition, less noise is produced The setting time of the cylinder is adjusted to the operating conditions Manual setting is possible (for special runs over the turnout from the turnout toe) If restricted space is available, it is also possible to arrange them in longitudinal direction of the track
Technical characteristics:
Field of application - For smaller to medium-sized turnouts which can be set with one lock Max. trailing speed - 40 kph Arrangement of recoiling cylinder - At the side of the closed switch
Special features: The switch stand is locked, the specific operating instructions must be adhered
5.1.7
Classification of Switches
The divergence and length of a switch is determined by the angle of the frog (the point in the switch where two rails cross) and the curvature of the switchblades. The length and placement of the other components are determined from this using established formulas and standards. This divergence is measured as the number of units of length for a single unit of separation. In North America this is generally referred to as a switch’s “number”. For example, on a “number 12” switch, the rails are one unit apart at a distance of twelve units from the centre of the frog. In the United Kingdom points and crossings using chaired bullhead rail would be referred to using a letter and number combination. The letter would define the length (and hence the radius) of the switchblades and the number would define the angle of the crossing (frog). Thus an A7 turnout would be very short and likely only to be found in dockyards etc. whereas a E12 would be found as a fairly high speed turnout on a mainline.
5.1.8
Layout of Switches
All measurements are referred to the actual point of the frog as a reference. If b is the width of the frog point, usually 1/2" or 12 mm, then the distance between the theoretical point and the actual point is nb. The analysis is done in terms of the theoretical point. The frog number n and the length of the points L are the other necessary parameters. We want to know the radius of the curve R connecting the points and the frog, as well as the distance E from the point of the frog to the toe of the points, called the lead. These measurements are sufficient for constructing the turnout. All we need to solve this problem is trigonometry, but it gives a better understanding to approach it by some approximate solutions. In the simplest case, assume that the curve is tangent to the straight at some point Q. If the gauge is g (standard gauge is 4.7083 ft, 56.5 in, or 1435 mm), then the radius of curvature of this rail is R + g/2. This arc crosses the other rail at some point P, which will be the theoretical point of the frog. Actually, frogs are made with straight rails except in some special cases, but we'll ignore that at this point. The angle of crossing is F. It is easy to see that g = (R + g/2)(1 - cos F), so that R + g/2 = g/(1 - cos F). Therefore, with a continuous circular arc from point to frog, the frog angle F determines the radius of curvature of the closure rail. The lead is E = (R + g/2) sin F. Let's apply this to a No. 12 frog, n = 12. then, F = 4.772°, from which R = 1355.9 ft, and E = 113.0 ft. E should be increased by the distance from the theoretical to the actual point, 12 x 1/2" = 6", or E' = 113.5 ft. Now, the frog rails are straight, and the distance from the theoretical point to the toe of the frog is k = 6.417 ft (from a table of frog dimensions). It's very easy to modify our formulas to allow for this. In fact, R + g/2 = (g - k sin F)/(1 cos F). Recalculating, R = 1201.9 ft. We must add k cos F = 6.39 ft to E, or E = 106.4 ft, E' = 106.9 ft. The effect of the straight portion of the frog is to decrease R and E somewhat. If it is convenient to decrease the lead, we can do this by adding a straight portion near the frog. In either case, we can easily arrange a stub switch. If we assume that the rail will assume a circular curve when deviated (which is not quite true), then the throw T = L2/2R, or L = √(2RT). For the example with a straight frog, L = 34.7 ft. This is rather long, since it is best if L is less than a rail length, so L was generally made a little shorter, and some angular misalignment was accepted. The switch rail is a cantilever beam loaded at the end, approximately. The deflection of such a beam is D = PL3/3EI, where P is the load, L the length, E the Young's modulus (for steel), and I the transverse moment of inertia of the rail section. For a modern 115 lb/yard section, I = 10.7 in4. For a 22 ft switch rail, the force P is 52.3 lb per inch of throw, or 314 lb for a throw of 6 in. When stub switches were used, rail sections were much lighter, and the force was correspondingly less. The addition of straight switch rails adds a little complication. If t is the thickness at the toe and h the heel distance, then the switch angle S is given by sin S = (h - t)/L, where L is the switch rail length. If h = 6.25" and t = 0.25", then for L = 11 ft, S = 2.605° and for L = 22 ft, S = 1.302°. We see that switch angles vary between 1° and 3°. This corresponds to an abrupt change of direction, which limits the speed at which the divergence can be taken. The formula for R is now R + g/2 = (g - h - k sin F)/(cos S - cos F), which we see becomes the stub-switch formula for S = h = 0. The theoretical lead E = L + [(g - h - k sin F)/tan(F + S)/2] + k cos F. To find the actual lead, nb must be added. For a No. 12 turnout with 22 ft switch rails, we find that F = 4.772°, S = 1.302°, (F + S)/2 = 3.037°, g - h - k sin F = 3.653 ft, so that R + g/2 = 1138.7 ft, or R = 1136 ft. (a 5° 3' curve). The theoretical lead is E = 97.25 ft, so E' = 97.75ft. These numbers are not far from those for a No. 12 stub switch.
Page 170 of 259
The general case is illustrated below:
Figure 291: Turnout
The length L of the switch rails includes any straight segment at this end of the curve, while the length k at the frog includes any straight segment there. To find R, we express the distance CD in two different ways. One way is g - h - k sin F. The other way is (R + g/2)(cos S - cos F). Equating these gives R + g/2 = (g - h - k sin F)/(cos S - cos F). If we increase L, we increase the heel distance h proportionately, and this decreases R. If we increase k, then R is also decreased. The lead E is the sum of L, the projection of AB, and k cos F. AB is (g - h - k sin F)/tan[(F + S)/2]. The angle ABD is [180° - (F - S)]/2 less 90° - F, or (F + S)/2. Therefore, E = L + [(g - h - k sin F)/tan(F + S)/2] + k cos F. If S is small, then a change in k produces an equal and opposite change in E. By increasing k, then, we can decrease E. On the other hand, increasing L will increase E by a somewhat smaller amount. By adjusting the straight segments at each end of the closure rail, we can change E by small amounts, to suit the rail lengths we have available. It is only necessary to insert an extra tangent at one end to make this adjustment. The AREA made a table of "practical leads" of this kind. For example, a No. 12 switch, with 22-ft switch rails, can use 3 24-ft rails for the curved closure rail, and 2 24-ft rails, plus a 23 ft 10-5/8 in rail for the straight closure rail. There is a tangent of 5.33 ft next to the switch rail, and no additional tangent at the frog. The actual lead is 100' 9-5/8", and the radius of the lead curve is 1098.73 ft. (Compare with the theoretical lead given above.) Many turnout applications involve parallel tracks. North American standard-gauge railway equipment is about 10 ft (3048 mm) wide, so parallel tracks must be a minimum of 12 or 13 ft between centres. A spacing of 14 ft or 15 ft gives satisfactory clearance. On a curve of radius R, a car with a distance D between truck centres will overhang a distance of about D2/8R. For D = 60 ft and R = 500 ft, this is 0.9 ft. Therefore, increasing the spacing by 1 ft for R between 1000 ft and 500 ft, and by 2 ft for smaller radii, should be sufficient. The overhang of the car corners should also be checked. We'll assume a spacing of p = 14 ft in what follows. Consider a crossover between two parallel tracks of spacing p. Let the frogs be the same, and suppose the connection is straight, which is the best practice, avoiding a reversed curve. If L is the distance between the point of one frog and the point opposite the toe of the other frog where the closure curve begins, then L sin F = p - q cos F + k sin F. The distance q between the frog theoretical points, measured parallel to the tracks, is then q = L cos F - g sin F - k cos F, or q = (p / tan F) - g(sin F + cos F). Subtracting 2nb then gives the distance between the actual points. When the location of the frog points is determined, the crossover can be constructed. The distance along the connecting track between points opposite the frog points is d = (p/sin F) - (g/tan F). For a No. 12 crossover between tracks 14 ft apart, F = 4.772°, so q = 162.62 ft. and d = 111.89 ft. The total length of the crossover, from point of switch rail to point of switch rail, is q + 2E = 357.12 ft. A second problem is to find the radius of the circular curve to connect with a parallel track. The central angle of this curve is F, so the mid-ordinate of the inner curve is (R - g/2)(1 - cos F). This is equal to p - g - s sin F, where s is the distance along a straight track from the theoretical point of the frog to the beginning of the curve (P.C.). Therefore, R - g/2 = (p - g - s sin F)/(1 - cos F). s includes the heel distance of the frog, but it is good to make s larger to avoid a reversed curve. For a No. 12 turnout, s = 30 ft, and p = 14 ft, we find R = 1962.9 ft. This is about a 3° curve. If the maximum allowed speed on the turnout is 25 mph, a circular curve is adequate, and superelevation is not required. Now consider a straight ladder connecting body tracks 14 ft apart. If there is no curve beyond the frog, the ladder angle is F. For a No. 8 ladder, this is 7.153°. A forward distance of 111.56 ft is required for each track, so a straight ladder occupies a great deal of space, and often ways must be found to reduce this distance by introducing curves. If E is the lead, and s the distance from the point of the preceding frog to the points of the switch rails, then p = (E + s) sin F. This can be solved for s, s = p/sin F - E. With a No. 8 ladder, and p = 14 ft, we find s = 44.96 ft. The distance between frog points is 112.43 ft.
Page 171 of 259
Suppose a curve is used beyond the frog, with a distance h between the theoretical point and the P.C.. The point at which this curve, projected backward, becomes parallel to the straight track is at coordinates x = R sin F - h cos F and y = R(1 - cos F) - h sin F, with x measured towards the points and y measured towards the other rail, as shown in the diagram. This construction is often useful when designing track layouts.
Figure 292: Curve Beyond Frog
5.1.9
Safety Aspect of Switches
The correct setting of points is fundamental to the safe running of a railway. For example, an incorrectly set switch may result in two trains being on the same track, causing a collision. Perhaps the greatest security challenge in railway operation is preventing the tampering of manually-operable switches. Similar (non-fatal) wrecks near Newport News, Virginia on August 12, 1992 and in Stewiacke, Nova Scotia on April 12, 2001 resulted from switches being thrown open in front of the trains by teenaged saboteurs. The Potters Bar rail crash at Potters Bar, Hertfordshire in the United Kingdom occurred in May 2002, when a switch sprang to a different position as a coach crossed it. The front wheels of a coach progressed along the straight track as intended, but the rear wheels slewed along the diverging track. This caused the whole coach to detach from the train and slew sideways across the platform ahead. Fortunately, the movement of the switch occurred beneath the final coach, so that although 7 people were killed, the front coaches remained on the tracks. Poor maintenance of the points was found to be the primary cause of the crash. Track-circuited turnouts must have the switch rails insulated from each other, so the tie rods must be provided with insulating joints. A circuit controller connected directly with the points should be adjusted so that a movement of 1/4" or 6 mm away from the stock rail will cause the track circuit to be shunted. A switch indicator in clear view of the switch stand (about 4 ft away, and 4 ft high) should show if the track circuit is shunted, that is, if a train is approaching. The indicator was usually a miniature semaphore. All arrangements to detect the position of the points, such as the switch box, must be connected directly with the points, and not to the operating rod. A facing-point lock has the dual functions of (1) proving that the switch rails are properly set in one direction or the other, and (2) preventing motion of the switch rails while engaged. A facing-point lock is not usually provided for hand-operated turnouts, but is used with motor-operated or interlocked turnouts that are controlled remotely. Originally, a facing-point lock was provided with fouling bars in the flangeways. In order to withdraw the facing-point lock, the fouling bars had to be raised first, which could not be done if wheels were passing over them. This protection is now provided by track circuits. The facing-point lock can either be in the stretcher bar between the switch rails, or at the side of the track, connected by a rod directly to the points. The plunger then engages in one of two holes, or else the switch rails are held directly by rotating lugs in their two positions.
5.1.10 Using Turnouts The failure of turnouts themselves seem to have caused very few serious accidents. The stub switch accident at Rio is one in which the turnout design contributed to the accident, but was not the cause. Spring switches have caused accidents when a partial movement is reversed, or when the points have not fit properly due to an obstruction. In general, problems with turnouts arise when they are not used properly. A misuse that has caused many accidents is that of the "open switch" when a train moving at speed encounters a facing turnout set for a low-speed divergence. A particular case of this kind of accident is discussed in The Open Switch, in which a switch is abruptly changed to the wrong position immediately in front of an approaching train, without malicious intent. This is a psychological peculiarity that can be defended against. Open switches can also result from malicious behaviour, in which points are slightly opened, or steps taken to display a clear lamp or target by mechanical means. This is discussed in Sabotage. It should be appreciated that an excessive speed may not be sufficient to cause overturning or derailment at the turnout itself; more dangerous is the possible collision with equipment on the diverted route.
Page 172 of 259
Under the Standard Code of Operating Rules in the United States, the use of turnouts was governed by Rule 104 and lettered supplements to it. Rule 104 outlined the responsibilities of employees handling switches. Main track switches were to be lined for the main track, secured and locked. Switches on a siding (track used for meets) were to be lined for the siding, secured and locked. Derails were to be set to derail and locked in that position. Switches used by a train were to be left in their normal positions, and the conductor was responsible for checking that this was done. Switches were not to be left open for another train; each train was separately responsible for its own switches. Rule 104(A), drafted by the individual company, prescribed the steps to be taken to ensure that a switch was not inadvertently opened in the face of a train. These were usually that the switch should be kept lined for the main track and locked until the expected train had passed, and that the employee lining the switch should stay a certain distance away (20 ft, the clearance point, across the track) until the train had passed. Rule 104(B) might prescribe that all switches involved in a movement (e.g., both switches of a crossover) must be lined before any track is fouled, and the movement should be completed before any switch is relined. And also, that a train must not be reported in the clear before the switches are lined and secured. Rule 104(C) might govern the use of spring switches, and mention not to reverse until the train is completely clear of the spring switch, not to use sand on spring or power switches, and that their locations are specified in the time table. Of course, these supplements varied with the different companies, but generally the matters mentioned were included. North America was unusual in the prevalence of hand-operated turnouts in main lines, a result of the light traffic density as well as of tradition. Even major passenger terminals, such as at New Orleans, Louisville and Dearborn Station in Chicago, to mention just a few, were until well after World War II operated by switchtenders that went from switch stand to switch stand setting routes, and then hand signalling to trains when they could enter or depart. This method of operation was suitable only with relatively light traffic and simple routes, but was remarkably successful and, above all, was cheap. It can be used safely only when there is a single switch tender responsible at any time, to avoid the confusion that early encouraged interlocking in Britain. Turnouts in a limited area were not controlled from a central location in the form of a ground frame in North America. Indeed, ground frames were unknown, their functions carried out by switch stands located at the turnouts. This avoided the problem of not knowing exactly what one was doing at a ground frame that necessitated interlocking. In particular, the turnouts involved in meeting (crossing) and passing trains were handled by the crew of the train using the siding. Main-line turnouts were kept padlocked, but the padlocks were not part of the signal system, so the turnouts could be operated at any time by anyone possessing a switch key. After about 1945, the development of CTC made the creation of small electric interlocking installations, as at important junctions, practical. These machines could be operated by the telegraph operator who also handled train orders, and controlled signals and turnouts on up to several miles.
5.1.11 Sabotage: The sad story of malicious tampering on America's railroads While preparing the page on accidents caused by throwing a switch irrationally in front of an oncoming train, I included for contrast a couple of accidents where the switch was maliciously misaligned. This made me wonder about how many accidents have been due to malicious actions, so I searched the ICC accident reports for the adjective "malicious," and discovered 95 reports. Some of these included the phrase "no malicious intent," and so were not germane. 78 reports remained, however, in which malicious intent was proved or suspected, dating from 1914 to 1958. These provided a depressing picture of such events, which are reviewed here for what lessons they contain. The word "sabotage" is not used often in ICC investigations (only two cases were found), but it does describe precisely these events. The word sabot means "wooden shoe" in French, and sabotage was originally just the word for the manufacturing of wooden shoes. However (so I understand) the wooden keys used to hold rails in chairs in the English fashion, which were widely used in France, are also called sabots. If you have a hammer, you can knock the keys out fairly easily and displace the rails. In the United States, the equivalent action is pulling spikes with a claw bar. This was done by saboteurs, and now the word, especially in English, refers to malicious tampering and destruction, usually as a clandestine act of war, or figuratively. I'll use the word here for brevity. Of the 78 cases of probable sabotage, more than half, or 45, involved tampering with switches (oddly, the word "turnout" is rare in ICC reports). In 34 of these, the switch was "open" or aligned for the divergence. An unsuspecting train might derail at the divergence, if it were moving rapidly (above 40 mph for the usual No 10 turnout), or more probably collide with equipment on the diverging track. In 11 of them, the switch was only "cocked," which means that the points were moved an inch or so from the stock rail so that the flange would drop between them and derail immediately. The next most common form of sabotage, in 11 instances, was tampering with the track, usually to disassemble a joint and displace one of the rails, or to unspike a rail and move it sideways. In 9 cases, objects were put on the tracks. This is seems to be a specialty of juveniles, and in most cases the objects are swept aside or noticed and removed without causing an accident. However, a craftier version puts objects on the high rail of a curve, where the flange pressure is ready to cause derailment. There was one accident due to an engine running away, sent on its way by malicious intent, and one case of a landslide at a cut that may have been caused by a dynamite explosion. One of the track accidents mentioned above, on an electric line near Niagara Falls, also involved dynamite to damage the track. There are similar accidents that do not involve malicious intent. One is the careless leaving of switches open or unlocked by trainmen, rather common accidents usually affecting yard and switching movements. Another is poor maintenance of switches, of which there was one example only in the ICC reports (CStPM&O, Mendota, MN 14 Mar 1914). There were two examples of switches run through incorrectly in the trailing direction. If this is not detected at the time, the switch is rendered hazardous to trains approaching in the facing direction, since the points are usually free to move or distorted. These cannot be detected on the train running through the switch unless one looks. In one of the two cases, the train derailed was instructed to look out for a switch run through that the block signals had detected, but a sufficient lookout was not maintained (PM, Glen Lord, MI, 28 May 1929). In most cases, an open switch can be detected from its switch light or target, if the weather is clear, in time to prevent an accident. In automatic block signal territory, a circuit controller operated by a rod from the switch points, sets the signals to stop when the points are not in the proper position. A break in a rail also interrupts a track circuit and protects the fault by the block signals. These protections can be defeated by a crafty wrecker, and
Page 173 of 259
sometimes by not maintaining good switch lights where there are no automatic block signals. The usual American manual block system also offers no protection against open switches or broken rails, since there are no track circuits or other electrical safety features. The most determined wreckers smash the switch lamp lenses, turn down the wick into the reservoir, and bend the target so it shows clear. The switch lock is sawed off, the points moved slightly and wedged with a stone or something. The rod to the circuit controller is detached by removing a cotter pin and a nut, so that it does not give protection. Although these measures are usually characteristic of an adult rogue, a 6-year-old once found a switch unlocked and amused himself by opening it, but could not close the switch properly again BR&P, Salamanca, NY, 21 Feb 1927). Three boys smashed the lock of a switch on the Piedmont and Northern (P&N, Greer, NC 22 March 1955) and replaced it. Later, a person unknown lined the switch for a coal dock, diverting a freight train with the loss of two lives. Main line switches are locked by stout padlocks that require some effort to remove, unless you happen to have a switch key. Switch locks have been removed from the vicinity to create the impression of malicious tampering when the fault lies with negligent trainmen. Tampering with the track is almost always the work of adult men, since it requires considerable physical power to pull the spikes, unscrew track bolts, and slew rails. These rogues realize what the bond wires at the joints do, and carefully do not break them. The current use of continuous welded rail prevents this sort of sabotage almost perfectly, except at what few rail joints remain. Outstanding examples of this are the accidents on the SP at Harney, NV on 12 Aug 1939, and on the PRR at Baden, PA, 16 Mar 1941. 9 passengers were killed in the first accident, and 2 in the second. The perpetrators were unknown, but the evidence points to disgruntled employees. Juveniles of limited mental capacity enjoy putting junk on rail heads, and this is aided by the practice of section crews to leave odd material lying around on the right-of-way. Certain areas became known for this and they should be carefully cleaned of junk so that there is no enticement. As mentioned above, adult perpetrators know how to use such junk to good effect, by placing it on the high rail at curves. On the Southern at Brennan, GA a 10-year-old put a rock on a track that derailed a train on 14 Feb 1933. A similar event occurred at Milltown, WI on 24 Feb 1948, where a Soo passenger train was derailed by stones on the high rail at a curve that derailed the engine truck of the locomotive. Three 11-year-olds were responsible. At Bloomfield, IN a 10-year old put a bolt and nut on the rail that derailed an Illinois Central freight train, killing 3 employees, on 25 August 1951. At Walton, IN on 27 January 1947 two boys dragged a roll of fence wire, some pipes and other hardware, all found nearby on the right of way, onto the track. Engine 5377 of No. 207, with 8 cars, running at 60 mph, wedged the junk into a turnout and derailed. Three passengers and an employee were killed. Many cases of obstructions on the track are not sabotage, but have other causes, such as a blown-down tree, or bulk cement carelessly spilled. A search of the ICC reports with the search phrase "obstruction near track" yields a surprising 290 documents. Of course, a number of these say no obstruction on the track, or words to that effect. Vincent Williamson was a notorious young train-wrecker of 1927-1928. At the age of 17 he escaped from the home for the feeble-minded at Salem, OR on 1 Jun 1927 with his buddy Herman Lemp and took to riding trains. Hobos were not created by the depression--they existed previously, and were a dangerous, violent mob of barbarians, not worthy of being made folk heroes. By August, Williamson and his buddies made it to Topeka, where they shot and killed a Union Pacific special agent who had ordered them off the property. They were put off a Chicago and Alton freight in February of the next year, and wrecked a passenger train at Independence, MO on the 15th of February by putting objects on the high rail at a curve. On the 24th, Williamson and a "negro" companion wrecked a Katy train at Parsons, KS by tampering with the track. Williamson wanted revenge for being put off at Fort Scott, the "negro" for being put in jail (I use the original words in the ICC report; it would seem unjust to say AfricanAmerican). They claimed they wanted to rob, but did not do so. On 7 March, Williamson and an associate Thaddeus Atkins put objects on the Union Pacific tracks at Lenape, KS, but failed to cause an accident. They did, however, succeed in being arrested. On 9 March, they earned 5 to 10 at the Hutchinson Reformatory, and on 26 March at Erie, KS they added 10 to life. One hopes that, in the event, it was closer to life. Note how little Williamson's victims were valued by their society. Malicious mischief was not confined to the track and switches. At Gallitzin, PA, the summit of the Pennsylvania Railroad's crossing of the Alleghenies, there was sabotage in December, 1931 that involved closing the angle cocks on the brake lines of trains about to descend the steep grades in either direction. This area was the site of derailments due to excessive speed in 1921, 1925, 1927 and twice in 1947. In one of the 1947 derailments, the 13th and last car of a passenger train, the 10-5 sleeper Cascade Mirage, became detached due to a defective coupler. Unfortunately, the hand brake was also defective and the brake reservoir was depleted, so the car derailed on a 9° 15' curve 3.37 miles east of Gallitzin. The other accidents, all to passenger trains, occurred on the notorious Bennington Curve, an 8° 30' curve 1 mile east of block station SF at the eastern portal of the Gallitzin tunnel. In the present case, Extra 4272 had reached the summit with 88 cars of coal, 7200 tons, with 3537 and 4463 as pushers. Between MO and AR, west of the tunnel, the conductor and brakemen turned up retainers for the descent. These would retain a certain pressure in the brake cylinders, keeping the brakes applied, while the engineman released the brakes and recharged the reservoirs. Speed was limited to 8 mph between MO and AR, and was supposed to be 12 mph through the tunnel to SF, but the speed was generally a bit higher. The descent begins before the west portal, so the brakes were applied in the tunnel, on the 1.39% descending grade. The engineman found very little exhaust, and discovered that the brakes were applied only on the engine, tender and about 12 cars of the train, hardly enough to be noticed on the 2.36% descending grade past SF. He whistled for brakes, but was not heard. A brakeman and the conductor were still on top of the train at this time, making their ways back to the cabin car. The flagman on the caboose did not open the conductor's valve, and by the time the conductor got there, it was too late. The train derailed on Bennington Curve, a mile east of SF, at 7.09 pm, moving at over 40 mph. It was discovered that the angle cock at the rear of the 12th car was closed. This was done some time after the brake test at Gallitzin, where the brake pipe pressure was raised to 100 psi, and the minimum of 85 psi was noted at the cabin car. The brake pipe behind the 12th car was properly charged,
Page 174 of 259
and if the conductor's valve had been opened promptly, there was probably sufficient brake power to stop the train. It was surmised that leakage had caused the brakes to creep on anyway, retarding the train more than the few brakes at the head end could do. Earlier, a westbound train had experienced trouble stopping at Gallitzin, and angle cocks were found closed. There had been several other incidents in the days before the event, none of which had had serious consequences. Two boys were seen hanging about and were probably responsible for the mischief. Direct sabotage of signals seems rare. Most malicious tampering with signals, such as cutting wires, would result in the display of the most restrictive aspect. It would require more intelligence than generally possessed by the average villain to cause a false clear. Of course, where there are automatic block signals, wreckers are careful not to disturb bond wires and to disconnect circuit controllers so the signals will not warn of the danger. The stimulus for nearly all of the cases of sabotage was either individual revenge or evil thrills and pleasure. Most of the perpetrators are unknown. Of the 78 accidents, only 12 were "solved." There were no claims of credit afterwards, so they were not intended as public demonstrations. Robbery was not a motive (except on the T&P at Mackle, TX 24 Nov 1922, where a extra section labourer cocked a switch so he could loot the derailed freight train). Dismissed employees sometimes turned rogue, as at Osgood, NC, 19 Jan 1915, on the SAL. Many of the track and switch tampering cases exhibit knowledge of railroad devices and operations that are not common knowledge. It is evident that the motive in most is sheer malice. The accident tolls fell most heavily on engine crews, who were innocent victims of the wreckers. Very few passengers were killed in all of these accidents taken together, which is the only comfort that can be derived. These accidents have continued, and several more recent accidents could be added, such as the sabotage west of Phoenix a few years ago on the SP. For the period 1911-1960, Shaw mentions two of the accidents included here, Henryetta and Harney. For the times before the ICC reports, he mentions 5 accidents, the first in 1868. Of course, the sabotage that occurred during the Civil War is properly excluded. If the same ratio of 2 to 78 is applicable to the earlier period, we can estimate a total of 273 incidents of malicious tampering from 1830 to 1966, about two per year on the average. Shaw concentrates on accidents that involve passenger fatalities, while most of the fatalities in these accidents are of the unfortunate engine crew, as we have already pointed out. This probably explains the disparity between Shaw's few mentions, and the results of my computer search. In contrast, Rolt's book on British accidents does not mention a single case of sabotage or malicious tampering in the same period. Access to the right-of-way may be slightly more difficult than in the United States, and there are more eyes and less isolation, but graffiti show that this is no barrier, especially in the urban areas where one might expect malicious behavior to be more common. There is also the almost complete absence of the tramp element, which has no doubt been responsible for a significant number of American incidents.
5.1.12 Mechanical Interlocking in a Freight Yard
Figure 293: Mechanical Interlocking 1 of 12
On the main railway line between Inverness and Aberdeen there is a small turnoff for the freight yard at Elgin. At first glance, it's fairly straight forward, just a switch (or a point, or a turnout -- depending on where you live). But it isn't...
Page 175 of 259
Figure 294: Mechanical Interlocking 2 of 12
In order to gain access to the yard, the train must stop and the driver has to get out and manipulate these controls. The first task is to pull the lever, which unlocks the switch.
Figure 295: Mechanical Interlocking 3 of 12
The control lever is connected to an amazing series of throwrods, reversers, adjusters and redirecting pivots. The whole system is mechanical and is Victorian technology.
Page 176 of 259
Figure 296: Mechanical Interlocking 4 of 12
Eventually the connection makes it to the locking rod which jams the railroad switch into either its left or straight positions. With the locking rod withdrawn, the switch is now free to be repositioned.
Figure 297: Mechanical Interlocking 5 of 12
But wait! There's a small connection between the locking rod and an interlock. This interlock is the key to the system. There are three rods (parallel to the sleepers) which come from the switch. These intersect with two rods (parallel to the tracks) which come from the signals. Each of these five rods has a sequence of notches in them. In this case, the locking bar on the switch will refuse to disengage unless both of the signals are set to 'stop'.
Page 177 of 259
Figure 298: Mechanical Interlocking 6 of 12
Now that the switch is unlocked, the driver pulls a second lever which moves the switch to the left. The throwrod which does this also deactivates the derailer. The derailer mirrors the switch position; whenever the switch is set straight (for the main line), the derailer will prevent stray freight cars from rolling out of the yard. They get sent to /dev/null instead.
Figure 299: Mechanical Interlocking 7 of 12
With the switch now pointing into the yard and the derailer deactivated, the next step is to slide the locking bar back into place. This will prevent the switch from moving under the weight of the train. It's just a matter of pushing the first lever back into position.
Page 178 of 259
Figure 300: Mechanical Interlocking 8 of 12
The next step is to raise the signal so that the train is cleared to enter the yard. This is done by pulling the third lever. This system doesn't use throwbars, it uses wire and pulleys and is always in tension. That way if there's a failure, a large weight at the signal will reset it back to 'stop'. Fail safe!
Figure 301: Mechanical Interlocking 9 of 12
On the way to the signal, the wire passes through the switch's interlock. The notches inside make it impossible to raise the yard signal unless a) the left rail of the switch is in the correct position, b) the right rail of the switch is in the correct position and c) the switch is locked.
Page 179 of 259
Figure 302: Mechanical Interlocking 10 of 12
Assuming all the conditions are met, then the small semaphore on the left will be raised. The train can now enter the yard. Then the whole process needs to be reversed to throw the switch back to the straight position.
Figure 303: Mechanical Interlocking 11 of 12
Once you get past that first switch, the rest is easy. Every switch thereafter is freely movable (and unlocked).
Page 180 of 259
Figure 304: Mechanical Interlocking 12 of 12
Er, oops! In summary, this ancient mechanical system is completely idiot-proof. The interlock prevents anyone from making an illegal move. It guards against mechanical failure. It checks the results of actions, not the actions themselves. If this is the control system for a simple switch for a little-used freight yard, you would hate to think what a major railway interchange looks like.
5.1.13 Accidents 5.1.13.1 Grayrigg Crash - Train crash points not inspected According to a rail industry report revelation, the faulty points that caused a fatal crash in Cumbria should have been inspected five days earlier. An 84-year-old woman was killed and 22 people injured when the London-to-Glasgow Virgin Pendolino plunged off the track at Grayrigg. Three days later an interim investigation blamed faulty points. A Network Rail report found systematic failures in track patrolling and management and identified a list of deficiencies in inspection and maintenance. It revealed that a visual inspection of the points was not carried out because the inspector decided "to finish early". Network Rail said the inspector's records clearly showed this, but the inspector's supervisor then failed to pick up that the inspection had been missed. The report makes 14 recommendations with a further 19 specific action plans to reduce the chance of anything similar happening again. After the accident, Network Rail accepted responsibility and offered apologies to everyone affected.
Important lessons Iain Coucher, chief executive of Network Rail, said: "I renew that apology today. The report makes for difficult and sobering reading. Mistakes were made and there are important lessons for all of us at Network Rail. We have already made changes and more change will follow as we put in place all the actions and recommendations put forward by this report." Tony Collins, chief executive of Virgin Rail Group, said: "This is a comprehensive report and clearly indicates some fundamental deficiencies at local level in Network Rail. It is crucial that we learn from the accident at Grayrigg and it is extremely positive that Network Rail has acknowledged the failings that led to the accident." A Rail Accident Investigation Branch inquiry is still ongoing. British Transport Police arrested a 46-year-old Network Rail employee from the Preston area and questioned him on suspicion of manslaughter. He was released on bail later.
Key Failures Stretcher bars maintain the distance between the switch rails, which allow trains to change tracks at points. The report found that one of the stretcher bars was missing, while damage to bolts on the remaining three bars allowed the left-hand switch rail to swing free and close the gap with the lefthand stock rail. When the front wheelsets of the Virgin Pendolino train hit the defective points, the deformed switch rails caused them to derail.
Page 181 of 259
Figure 305: This is how points work
Figure 306: This is what happened
Page 182 of 259
5.1.13.2 Potters Bar crash - Several Potters Bar points 'were faulty'
Figure 307: This is what happened
The missing nuts Investigations so far suggest that nuts were missing from two stretcher bars. The bars have the crucial job of holding the switch rail in place. With the nuts missing the lock stretcher bar failed due to the extra stress it was placed under. This forced the switch rail to move to the right, leaving little room for the train's wheels making a derailment almost inevitable.
The trouble with points 2182A According to the Health and Safety Executive the points failed because loose nuts forced the right hand switch rail out of its position. This left the train unable to pass over the points normally. As it travelled forward at over 100 mph the train's axles were compressed into an ever smaller area until they were forced to jump up off the tracks, de-railing the train's final carriage.
Sabotage has again been discounted Investigations have revealed that up to 20% of nuts on points near Potters Bar station were not fully tightened. The second interim report into the fatal train crash at the Hertfordshire station was published on Thursday and confirmed that the much-discussed set of points the train rode over before the accident was faulty. But is also showed that others in the area were below standard.The derailment resulted from nuts missing in adjustable stretcher bars in the points, which caused them to fail catastrophically. The report, by the Health and Safety Executive, discounted claims by maintenance contractor Jarvis that sabotage could be the cause of the problems with the main points. It backed the first report's findings that there was "no evidence" to support those "speculation" theories, although HSE inspectors were "keeping an open mind". After the report's release, the leader of the train drivers' union Aslef said prosecutions should now be "urgently considered". Seven people died and dozens were injured when the King's Cross to King's Lynn passenger service came off the tracks while passing over the points. The HSE report recommended Railtrack and its contractors should review the standard, specification and design of points.
Wedged It confirmed the first report's preliminary conclusions that nuts missing from a part of the points caused those points to "fail catastrophically".
Figure 308: The crash site
Page 183 of 259
The train's rear coach detached from the others and came to rest on its side, wedged under the station canopy. But the report went on: "It is too early in the investigation, which is being led by British Transport Police, to pronounce definitively on the direct or root cause of the accident." The nuts were missing from adjustable stretcher bars which keep the moveable section of track at the correct width for the train's wheels. The HSE said the set up of the main points in question - designated as number 2182A - was found "not to be as designed". But it also said a test of a sample of nuts on the stretcher bars of other points in the Potters Bar area had indicated that "20% were not fully tight".
'Design gaps' The report added that the points were undergoing detailed examination at an HSE laboratory in Buxton, Derbyshire, and this had "identified other differences in their condition compared to the standards expected". Some fastenings could not be tested with the tools available because of "design gaps," the HSE said. The report added: "The results of tightness tests of the nuts on stretcher bars in the area around Potters Bar indicate there may be mechanisms that cause nuts to lose tightness." Victims have blamed "poor maintenance" and "botched privatisation", and police focus has fallen on maintenance workers.
New investigative body British Transport Police have been hunting five "mystery" workers wearing orange jackets, seen on the track hours before the Potters Bar train crash. But no-one from Railtrack or Jarvis knows who they were, and police inquiries have so far failed to trace them. Transport Secretary Alistair Darling earlier this week announced that a new body would be set up to replace the HSE in investigating train crashes. That followed criticism by victims of the Potters Bar crash over the speed and efficiency of the HSE's investigations.
Contracting questions Author Nina Bawden, who lost her husband and was herself badly injured in the crash, said it was difficult to have faith in the HSE because of its dual role in both regulating and investigating the railways. She pointed out that its final report into the Hatfield crash in October 2000 had still not been published almost two years after the event. Mr. Darling has also criticised the chain of contracting-out in the rail industry, saying it is "a big issue and a problem that we know has to be sorted out". He said the problem was not the use of subcontractors, but the lack of proper checks on them.
5.1.13.3 Derailment of train EC 107 (Prague-Warsaw)
Figure 309: Derailment of train EC 107 (Prague-Warsaw) in Prague on 17th Feb 07. Broken switch tongue was reason of derailment.
Page 184 of 259
Figure 310: Derailment of train EC 107 (Prague-Warsaw) in Prague on 17th Feb 07. Broken switch tongue was reason of derailment.
5.1.13.4 Abergele train disaster
Figure 311: Abergele Train Disaster
Page 185 of 259
The Abergele Train Disaster in 1868 was, up to that time, the worst railway disaster in Britain.
Overview On August 20, 1868, at 7.30 a.m., the Irish Mail train left the Euston Station in London for Holyhead. It pulled four passenger carriages, a mail van and a travelling post office. At 11.30 a.m. in Chester, it collected four additional passenger carriages that were attached immediately behind the locomotive. After an hour the train was approaching Abergele in north Wales. At the same time at Llandulas to the west of Abergele, railway workers shunted cargo trucks from the main line to the sidings. During the shuffling, they had to leave six trucks with a brake van on the main line. Two of the trucks carried barrels of paraffin. When some of the trucks were shunted against them, the brakes in a brake van slipped, and the trucks begun to slide down the incline toward the Irish Mail. Engine driver Arthur Thompson saw the trucks speeding towards the train from behind the curve of the sea wall. He turned off steam and threw the engine into reverse, but it was too late. He jumped just before the inevitable collision, suffering serious injuries. When the cargo trucks collided with the engine, the paraffin exploded, and fire engulfed the locomotive and the first four carriages, killing 32 passengers and the fireman in a matter of seconds. A number of labourers ran to the scene from a nearby quarry and formed a human chain, trying to quench the flames with seawater; however, they failed to save anyone. (The bodies were so scarred that only three of them could be later identified.) The victims were buried in a mass grave in St Michael’s churchyard in Abergele, with the London & North Western Railway Company paying all funeral expenses. During the inquest, the coroner received an anonymous letter that put the blame on the Fenians; the Irish rebels had supposedly tried to assassinate the wife and servants of the Lord Lieutenant of Ireland. The inquest did not find any kind of evidence to support this, and the letter was declared a hoax. Injured Arthur Thompson was unfairly suspected of speeding but there was much sympathy for him; he died of his injuries in October. Llandulas’ brakemen assured that they were very careful, although some witnesses claimed they had seen runaway trucks before. The brakemen were not prosecuted, but were criticised by the Board of Trade Inspector, Colonel Rich, for shunting on the main line too soon before the express was due. He also criticised the railway company for an inadequate siding layout.
Aftermath It became the practice for steep inclines to be fitted with runaway catchpoints so that runaway vehicles would be derailed and stopped before they had a chance to collide with following trains. These catchpoints became widespread, and only diminished in numbers when all rolling stock was fitted with continuous automatic brakes in the 1980s. Among those who lost their lives in the disaster were the Rt. Hon. Baron Henry Farnham K.P., aged 68 from Farnham, Cavan, Ireland and his wife Anna. Lord Farnham’s remains were identified by the crest engraved on his watch. A statue to his memory now stands outside the new Johnston Central Library in Farnham St., Cavan.
Similar Accidents The fatal accident involving in the USA, Casey Jones also involved a station with sidings not long enough to hold the whole train clear of the main line.
Page 186 of 259
5.2 Junctions
Figure 312: Junction
Figure 313: World's most complicated railway crossing – Frankfurt Germany
Page 187 of 259
What is!
5.2.1
A junction, in the context of rail transport, is a place at which two or more rail routes converge or diverge. This implies a physical connection between the tracks of the two routes (assuming they are of the same gauge), provided by 'points' (US: switches) and signalling. In a simple case where two routes with one or two tracks each meet at a junction, a fairly simple layout of tracks suffices to allow trains to transfer from one route to the other. More complicated junctions are needed to permit trains to travel in either direction after joining the new route, for example by providing a triangular track layout. In this latter case, the three points of the triangle may be given different names, for example using points of the compass as well as the name of the overall place. Railroad operations refer to stations that lie on or near a railway junction as a junction station. Frequently, trains are built up and taken apart (separated) at such stations so that the same train can split up and go to multiple destinations. For goods trains (US: freight trains), marshalling yards (US: Classification yards) serve a similar purpose. The world's first railway junction was Newton Junction near Newton-le-Willows, England, when in 1831 two railroads merged.
5.2.1.1
Measures to improve junction capacity
The capacity of the junctions limits the capacity of a railway network more than the capacity of individual railway lines. This applies more as the network density increases. Measures to improve junctions are often more useful than building new railway lines. The capacity of a railway junction can be increased with improved signalling measures, by building points suitable for higher speeds, or by turning level junctions into flying junctions. With more complicated junctions such construction can rapidly become very expensive, especially if space is restricted by tunnels, bridges or innercity tracks.
5.2.2
Flying Junction
A flying junction is a railway junction at which one or more diverging or converging tracks in a multiple-track route cross other tracks on the route by bridge to avoid conflict with other train movements. A more technical term is "grade-separated junction". A burrowing junction or dive-under is where the diverging line passes below the main line. Simple flying junctions may have a single track pass over or under other tracks to avoid conflict, while complex flying junctions may have an elaborate infrastructure to allow multiple routings among a variety of tracks without trains coming into conflict, in the manner of a highway stack interchange. The alternative to grade separation is a level junction or flat-junction, where tracks cross at grade and conflicting routes must be protected by interlocked signals. Nearly all junctions leaving or joining high-speed railways are grade-separated. On the French LGV high-speed network, junctions allow 300 km/h+ (normal line speed) along the direction of the mainline, and a limit of 160 km/h for the diverging path. The LGV network is large enough to contain four fully grade-separated high-speed triangles: Fretin (Lille), Coubert (south-east Paris), Messy (east of Paris) and Angles (Avignon). A fourth triangle, Vémars (north-east Paris) is grade-separated except for a single-track link on the least-commonly used side (southern end linking Paris Gare du Nord to Paris CDG airport).
Figure 314: Flying junction: with a bridge, trains do not block each other
Figure 315: Fretin triangle, France: Each side is over 3 km (2 mi) long. TGVs and Eurostars cross it at 300 km/h (186 mph)
Page 188 of 259
5.2.3
Level Junction
A level junction comprises two pairs of switches linking two tracks to each other in both directions. In U.S. railroad practice, a level junction (or in the United Kingdom a flat junction) is a railway junction that has a track configuration in which merging or crossing railroad lines provide track connections with each other that require trains to cross over in front of opposing traffic at grade. The structure used is a diamond junction or diamond crossing in reference to the diamond-shaped centre. Routings must be controlled by signals and an interlocking plant, or by an automated Centralized Traffic Control (CTC) system. The two tracks need not be of the same gauge. Level junctions, particularly those of fine angles or near right angles, create derailment risks and impose speed restrictions. The former can occur as the flanges of the wheels are momentarily unsupported and unguided and can slip through the gaps in the rails, and the latter due to the fact that the assembly contains elements that can break or vibrate loose. Level junctions are considered a maintenance issue by railroad companies as the inherent gaps tend to be hard on locomotive and rolling stock wheelsets. Switched diamonds partially solve these problems, but introduce some new problems. If possible, diamonds should be replaced by a pair of turnouts. The opposite of a level junction is a flying junction, where individual tracks rise or fall to pass over or under other tracks. A diamond crossing is also used as a component of a Double junction.
Figure 316: Flat junction: trains have to wait to cross the 'diamond' at the centre
Figure 317: A schematic diagram of a dual-gauge diamond crossing
Figure 318: Central Trains diesel multiple unit on a Nottingham-Derby-Stoke train arrives across London Road Junction, Derby 21st Sept 2005. The junction pointwork is still quite complex with several diamond crossings.
Page 189 of 259
Figure 319: This 'rotten' diamond crossing has recently been reduced from 50 kph to 30 kph, any wonder !!!!
Figure 320: Unusual prefab 2 ft gauge diamond crossing
Page 190 of 259
Figure 321: Railroad crossing at grade, also known as a diamond crossing or level junction. This example is located in Mulberry, Florida.
Figure 322: Components of an abandoned level junction assembly (Beside the current BNSF Railway main line in Orange, California. The structure used to allow trains of the Atchison, Topeka and Santa Fe Railway and Southern Pacific Railroad to cross over one another's lines)
Page 191 of 259
Figure 323: A temporary level junction. This allows Sacramento Southern Railroad trains to pass over the Union Pacific tracks in Sacramento, California. The components must be installed, railroad cars moved, and the assembly dismantled in less than 30 minutes so as not to impede UPRR freight and Amtrak passenger train movement along the main line.
Figure 324: Diamond (level) crossing in Ratlam, India
Page 192 of 259
Figure 325: A fully assembled level junction in the foreground. It will replace the one in the background where Union Pacific and Kansas & Oklahoma tracks cross.
Page 193 of 259
Figure 326: The Brickworks at Ledo, Assam. The narrow gauge line crosses our road and then the broad gauge tracks too. Note the diamond crossing of the BG and NG lines in the foreground. the line beyond into the brickwork complex seems to have been ripped off, and the gate walled up.
Page 194 of 259
Figure 327: Lap Beam Manganese Diamond Crossings AMS (Austenitic Manganese Steel)
Figure 328: Diamond crossing with cast manganese frogs
Page 195 of 259
Figure 329: Train crossing a diamond crossing
5.2.3.1
Examples
Flat crossings are particularly common in the United States where the lines of one company cross the lines of another company, and there is no particular need for the lines to be connected for through traffic. A notable example is Newark flat crossing, United Kingdom, which is on the East Coast Mainline, and the Lincoln to Nottingham line. It is certainly the fastest in the UK, with East Coast trains allowed to cross the junction at 100mph (160 km/h). Flat crossings also appear in some urban passenger rail systems, which can cause delays at peak hours as a train heading in one direction may have to wait for trains headed in another direction to clear the junction before it can cross. The junctions leading onto and off from the Loop of the Chicago El are examples of this problem. The New York City Subway system uses mostly flying junctions, but in a few older parts of the system, flat crossings can still cause delays. Examples include the crossing in Upper Manhattan where the uptown (northbound) "3" line departs from the Lenox Avenue line and turns toward the west, crossing over the tracks of the downtown "2" line. Diamond crossings between meter and broad gauge tracks are formed in Indore and Ratlam in India. At Rochelle Railroad Park, the double track UP mainline crosses the double track BNSF mainline forming four diamond crossings altogether at this location.
5.2.3.2
Drawbridge crossing
In Queensland, Australia flat crossings between narrow gauge cane tramways and main lines are being replaced by drawbridges so that the rails of the main line are completely unbroken by gaps or weak spots; this allows the main line speeds to be raised.
5.2.4
Double junction
A double junction is a railway junction where a double-track railway splits into two double-track lines. Usually, one line is the main line and carries traffic through the junction at normal speed, while the other track is a branch line that carries traffic through the junction at reduced speed.
Figure 330: Double junction at Bedford
A number of configurations is possible.
Page 196 of 259
5.2.4.1
Diamond
The simplest and oldest arrangement consists of two turnouts and a diamond crossing. Because the diamond needs to be relatively coarse, say 1 in 8, the curve radius is necessarily small, leading to a speed of perhaps 25 km/h. This type of junction is common on street-running tramways, where speeds are quite low and junction must fit into the available road space.
SPAD protection A train from R to P with 12 points reverse is protected from a train from P doing a SPAD by 11 points also lying reverse. A train from P to Q is not protected from a train from R doing a SPAD.
Figure 331: Double Junction with Diamond
5.2.4.2
Switched diamond
Although not strictly speaking a turnout, a switched diamond is an active trackwork assembly used where the crossing angle between two tracks is too shallow for totally passive trackwork. These vaguely resemble two standard points assembled very closely toe-to-toe. These would also often utilise swingnose crossings at the outer ends to ensure complete wheel support in the same way as provided on shallow angle turnouts.
Figure 332: A switched diamond with two swingnose crossings at a UK junction
The fixed diamond can be replaced with a switched diamond, which eliminates the gap in rails at the K-crossing. However, switched diamonds are not a perfect solution to the K-crossing problem, as the switches are very coarse compared to the finer switches of a turnout, and require high maintenance.
Figure 333: Double Junction with Switched Diamond
Page 197 of 259
5.2.4.3
Ladder
An improved junction replaces the diamond with turnouts, which can be of as fine an angle as possible, so that this junction can carry branch traffic at high speed. This configuration assumes power operation of the points, as high speed turnout are generally not suitable for mechanical operation. The high speed turnouts may require more than one point machine each. The turnouts can have no super elevation while the curve in the branch can; therefore the radius in the turnouts must be greater than the radius of the curve in the branch.
SPAD protection Essentially the same as for a Double junction with Diamond.
Figure 334: Double Junction with Ladders
5.2.4.4
Single lead
A single lead junction is used where traffic density is lower, and moves one of the turnouts on the main line onto the branch. This may reduce the number of turnouts on the main line that are subject to heavy wear and tear. The diamond crossing is inherently a heavy wearing component due to the gaps in the K-crossings, and this configuration eliminates the diamond. However, unlike in the ladder, branch trains in opposite directions can collide head-on at 32 if either one passes a signal at danger (SPAD). This has contributed to fatal accidents, e.g. in the UK at: Glasgow Bellgrove on 6 March 1989 and Newton on 21 July 1991.
Figure 335: Double Junction with Single Lead
5.2.4.5
Diamond and wide centres
A double junction with a diamond can have its speed limit raised if the track centres are widened to allow for a coarse-angled diamond crossing with fine-angled turnouts. Examples are at Cabramatta, Wootton Bassett.
SPAD protection Essentially the same as for a double junction with diamond.
Figure 336: Double Junction with Diamond & Wide Centres
Page 198 of 259
5.2.4.6
Flyovers
A double junction can be grade separated so that there is no flat crossing, reducing conflicts and reducing congestion. Flyovers require a lot of space both lengthwise and crosswise, and cannot always be built. Flying junction example at Aynho Junction. Diving junctions such as at Chatswood are a variant.
SPAD protection Because the diamond crossing or equivalent is eliminated, one of the potential SPAD hazards is also eliminated, leaving just the merging junction hazard.
Figure 337: Double Junction with Flyover
Figure 338: Chatswood Junction
5.2.5
Grand Union
Figure 339: Grand Union
In North American street railway practice, a grand union is a rail track junction where two two-track railway lines meet, usually at a street intersection, and railroad switches allow any streetcar coming from any direction to turn either left or right onto the intersecting line. These complex junctions, an example of special work, offered great operating flexibility, but were expensive to build and expensive to maintain. Special parts, sometimes made of manganese steel, were needed for each location where one rail crossed another, and these parts often needed to be custom-made and fitted for each location. One of the largest street railway operations, in Brooklyn, New York City, did not have a single grand union. The most extensive surviving street railway system in North America, which has several, is the Toronto streetcar system of the Toronto Transit Commission in Toronto, Canada. The one time Montreal Tramways Company or Montreal street railway system also had a number of them.[citation needed] The only surviving grand union in the Southern Hemisphere is Balaclava Junction in Melbourne, Australia. New Zealand formerly had two in Auckland, at Queen Street's intersections with Customs Street and Wellesley Street.
Page 199 of 259
5.3 Running Lines 5.3.1
Mainline or Main line
Mainline or Main Line is a track that is used for through trains or is the principal artery of the system from which branches, yards, and spurs are connected. This is a route between towns as opposed to a route providing suburban or metro services. Mainline tracks are typically at higher speeds than branch lines and are usually maintained and built to a higher standard than yards and branch lines. In the UK, the term "Mainline" may also be used to distinguish any train or track that isn't part of a light-rail or underground network. A closely related aspect is that of safety and is called track possession which is the authority to exclusively use a section of track. Depending on local regulations, it is permissible to carry out work or inspection on track without possession provided that all equipment may be removed instantly into a safe area.
5.3.2
Branch line
A branch line is a relatively minor railway line, which branches off a more important through route. A very short branch line may be called a spur line. Many British branch lines were closed as a result of the “Beeching Axe” in the 1960s, although some have been re-opened as heritage railways. The smallest branch line that is still in operation in the UK is the line from Stourbridge Junction going to Stourbridge Town. This only has one track. The journey is 1/3 of a mile (536 m) and the train takes around 55 seconds to complete its journey. In North America, little used branch lines are often spun off from larger railroads to become new common carrier short-line railroads of their own. New Zealand once had a very extensive network of branch lines, especially in the South Island regions of Canterbury, Otago, and Southland. Many were built in the late 19th century to open up regions inland from coastal harbours and cities for farming and other economic activities. The branches in the aforementioned South Island regions were often general-purpose lines that carried predominantly agricultural traffic, but lines elsewhere were often built to serve a specific resource. On the West Coast, an extensive network of branch lines was built in rugged terrain to serve coal mines, while in the central North Island and the Bay of Plenty, lines were built inland to provide rail access to large logging operations. Today, many of the branch lines have been closed, including almost all of the general-purpose country lines. Those that remain serve ports or industries not located near main lines such as coal mines, logging operations, large dairying factories and steelworks. In Wellington, two branch lines exist solely for commuter passenger trains.
Figure 340: The '0 kilometre peg' marks the start of a branch line in Western Australia.
5.3.3
Single Track
A single-track railway is one where traffic in both directions shares the same track. In the early days of railways, especially before the telegraph, operation of significant numbers of trains on a single track railway was fraught with difficulties, including delays and accidents, particularly head-on collisions. Some early wagon ways such as the Gloucester and Cheltenham Railway (which was really a tramway operated by horse power), were primarily single track with crossing loops at frequent intervals. The crossing loops were arranged to be in line of sight of one another, so that drivers in one direction could see if vehicles in the opposing direction were already in the single line section. The single line sections needed to be straight, so the profile of the line tended to be a series of chords rather than a smooth arc. When a single-track railway is converted to a double track railway, in some countries this is called duplication. The converse operation, converting a double track railway to single track, is known as singling. Though single track is significantly cheaper to build, it has a number of operational disadvantages. Single track typically has only one seventh of the capacity of a double track, rarely allowing more than about three trains an hour per direction, depending on the passing track frequency, while a double track typically can allow between 20 and 30 trains per hour. Also, there can be problems with long freight train if there are not enough long enough passing stretches, reducing the capacity of the track even more. Other disadvantages include the spread of delays, since if one train on a single track is delayed, any train waiting for it to pass also will be delayed, and will continue on to delay more trains. Also, single track does not have a "reserve" track that can allow a reduced capacity service to continue if one track is closed, but not the other.
Page 200 of 259
5.3.4
Double Track
A double track railway usually involves running one track in each direction, compared to a single-track railway where trains in both directions share the same track.
5.3.4.1
Overview
In the earliest days of railways in the United Kingdom, most lines were built as double track because of the difficulty of co-ordinating operations prior to the invention of the telegraph. Also the lines tended to be busy enough to be beyond the capacity of single track anyway. In the earliest days of railways in the United States, most lines were built as single track for reasons of cost, and very inefficient timetable working systems were employed to prevent head on collisions on single lines. This improved with the development of the telegraph and the train order system.
5.3.4.2
Operation
Handedness
Figure 341 Platform 1 is for trains north and east bound, platform 2 is for trains south and west bound
In any given country, rail traffic generally runs to one side of a double track line, which is not necessarily the same side that road vehicles in the same country keep to. Thus in Belgium, France (apart from the former German Alsace and Lorraine), Switzerland, Italy and Taiwan for example, the railways use left hand running, while the roads use right hand running. Where the French railways that use left hand running meet the German railways that use right hand running, flyovers are provided to convert from one hand to the other. Many countries do not have a great amount of double track, so the question is moot.
Bi-directional running Double track railways, especially older ones, use each track exclusively in one direction. This simplifies the signalling systems, especially where the signalling is mechanical. Where the signals and points are power operated, it can be worthwhile to signal each line in both directions, so that the double line becomes a pair of single lines. This allows trains to use one track where the other track is out of service due to track maintenance work, or a train failure, or for a fast train to overtake a slow train.
Page 201 of 259
Crossing loops Crossing loops, while consisting of two or more tracks, are not normally regarded as double track. If the crossing loop is long enough to hold several trains and to allow opposing trains to cross without slowing down or stopping, then that may be regarded as double track. A more modern British term for such a layout is an extended loop.
Track centres The distance between the track centres makes a difference in cost and performance of a double track line. The track centres can be as narrow and as cheap as possible, but this precludes maintenance workers standing safely between the lines. Signals for bi-directional working cannot be mounted between the tracks so must be mounted on the 'wrong' side of the line or on expensive signal bridges. Very narrow track centres are also undesirable for high speeds, as pressure waves knock each other as high speed trains pass. Narrow track centres that are 4m or less may have to be widened on sharp curves to allow long rail vehicles follow the arc of the curve, thereby increasing the workload for the surveyor. Increasing the track centres to 5m or so would suit high-speed trains passing each other, thus eliminating a need to widen the centres on sharp curves. If the track centres are increased to 6m or so, signals and overhead wiring structures can always be mounted on the ground. Very wide centres at major bridges can have military value. It also makes it harder for rogue ships and barges knocking out both bridges in the same accident. Railway lines in desert areas affected by sand dunes are sometimes built on alternate routes so that if one is covered by sand, the other(s) are still serviceable.
Temporary single track When one track of a double track railway is out of service for maintenance or a train break down, all trains may be concentrated on the one good track. There may be bi-directional signalling and suitable crossovers to enable trains to move onto the other track expeditiously (example, Channel Tunnel), or there may be some kind of manual safeworking to control trains on what is now a section of single track. Accidents can occur if the temporary safeworking system is not implemented properly. Examples include the Bruehl train disaster in 2000 and the Zoufftgen rail crash in 2006.
Passing Lanes To improve travel times and increase line capacity the 300km of line between Junee and Melbourne is to be partially duplicated in a configuration called Passing Lanes. Existing crossing loops are mostly 900m and 1500m long, and these will be enhanced by loops 6000m long which are long enough to be regarded as nearly double track.
5.3.4.3
Construction
Duplication The process of expanding a single track to double track is called duplication or doubling. The strongest evidence that a line was built as single track and duplicated later consists of major structures such as bridges and tunnels that are twinned, e.g. the twin Slade tunnels on the Ilfracombe Branch Line. Twinned structures may be identical in appearance or, like some tunnels between Adelaide and Belair, substantially different.
Tunnel Duplication Tunnels are confined spaces and are difficult to duplicate while trains keep on running. Generally they are duplicated by building a second tunnel. An exception would be the Hoosac Tunnel which was duplicated by enlarging the bore.
Provision for duplication To reduce initial costs of a line that is certain to see heavy traffic in the future, a line may be built as single track but with earthworks and structures designed for ready duplication. The Strathfield to Hamilton line in New South Wales Australia was constructed mainly as single track in the 1880s with full duplication only completed around 1910. All bridges, tunnels, stations, and earthworks were built for double track. The former B & O Railroad Washington-Jersey City line is an example of a duplication line that was reduced to single track in most locations, but has since undergone duplication in many places between Baltimore, Maryland and Philadelphia, Pennsylvania when CSX increased freight schedules in the late 1990's.
Page 202 of 259
Never used provision for duplication Some lines are built as single track with provision for duplication, but the duplication is never carried out. Examples include:
Bluebell Railway: Horsted Keynes to Lewes. Keighley and Worth Valley Railway - including bridge and tunnels and a deviation. Westerham in Kent. Monkerei Tunnel in New South Wales - double track size reduced fume problem in tunnel.
Singling When the capacity of a double track railway is in excess of requirements, the two tracks may be reduced to one. In some countries, this is called singling.
Tunnel singling A double track tunnel with restricted clearances is sometimes singled to form a single track tunnel with generous clearances, such as the Connaught Tunnel in Canada or the Tickhole Tunnel in New South Wales. In the case of the Tickhole Tunnel a new single track tunnel was built and the two tracks in the original tunnel were replaced by one track in the centreline of the tunnel. A notorious case where this was necessary was the Hastings Line in the United Kingdom, where the tunnels were eventually singled to permit the passage of standard British-gauge rolling stock (prior to the singling, narrow bodied stock was used, specially constructed for the line).
5.3.4.4
Oddities
Non-parallel double track The two tracks of a double track railway do not have to follow the same alignment if the terrain is difficult. At Frampton, New South Wales the uphill track follows something of a horseshoe curve at 1 in 75 gradient, while the shorter downhill track follows the original single track at 1 in 40 grades. Between Junee and Marina the two tracks are at different levels, with the original southbound and downhill track following ground level with a steep gradient, while the newer northbound and uphill track having a gentler gradient at the cost of more cut and fill.
Split ownership An unusual stretch of double track in west United States comprises two separate single-track lines owned by separate companies. However, the capacity of the two tracks has been greatly increased when they are combined and operated as if they were a double track line. Canadian Pacific and Canadian National are starting to do the same. Another example is in Conshohocken, Pennsylvania where the former Reading Railroad and Pennsylvania Railroad shared lines and even overhead electrical wire supports for a 2-mile stretch on the northern bank of the Schyulkill River. Both lines eventually came under Conrail ownership in 1976 with the PRR line now abandoned and used as a hike/bike path.
Mixing double and single track Because double and single track may use different signalling systems, it may be awkward and confusing to mix double and single track too often. For example, intermediate mechanical signal boxes on a double track line can be closed during periods of light traffic, but this cannot be done if there is a single line section in between. This problem is less serious with electrical signalling such as CTC.
Page 203 of 259
5.4 Rail Siding
Figure 342: Rail Siding
A siding, in general rail terminology, refers to a section of track distinct from a through route such as a main line or branch line or spur. It may connect to through trackage or to other sidings at one or both ends. The distinction between sidings and other types of trackage is somewhat vague, but in general “siding” denotes an auxiliary and often unspecific usage. The most common type of siding is that used to store stationary rolling stock, especially for loading and unloading. Such “industrial sidings” might be found at factories, mines (mining), quarries, wharves, warehouses, etc. Such sidings can sometimes be found at stations for public use; in American usage these are referred to as team tracks (after the use of teams of horses to pull wagons to and from them). Sidings are also used to temporarily hold railroad equipment between uses. A siding could hold maintenance of way equipment to allow other trains to pass, or a helper engine between runs.
5.4.1
Crossing Loop / Passing Siding or Loop
Figure 343: Passing Loop
Page 204 of 259
Figure 344: Funicular Passing Loop
A particular form of siding is the passing siding (crossing loop in British usage). It is also called a Refuge Loop or Siding used on double track lines. This is a section of track parallel to a through line and connected to it at both ends by switches. Passing sidings, as the name implies, are constructed to allow one train to pass another, and for fast, high priority trains to pass slower or lower priority trains going the same direction. It is a place on a single line railway/tramway where trains/trams running in opposing directions can pass each other or where trains/trams running in the same direction can also overtake, providing that the signalling arrangement allows it. They are important for efficiency on single track lines, and add to the capacity of other lines. The passing loop connects to the main track at both ends of the station, though a dead end siding, which is much less convenient, can be used. Ideally, the loop should be longer than all trains needing to cross at that station. If one train is too long for the loop it must wait for the opposing train to enter the loop proceeding, taking a few minutes. Ideally, the shorter train should arrive first and leave second. If both trains are too long for the loop, time-consuming "see-sawing" operations are required for the trains to cross. On railway systems that use platforms for passengers to board and disembark trains, especially high level platforms, platforms may be provided on both main and loop tracks or just the main track.
5.4.1.1
System of working
Main and Loop Working
Figure 345: Crossing Loop – Main & Loop Working
The main line has straight track, while the loop line has low speed turnouts at either end. If the station has only one platform, then it is located on the main line. An example is Clarendon railway station, Sydney on the Richmond line. If passenger trains are relatively few in number, and the likelihood of two passenger trains crossing each other, the platform on the loop line may be omitted.
Platform Road and Through Road Working
Figure 346: Crossing Loop – Platform & Through Working
The through road has straight track, while the platform road has low speed turnouts at either end. Riverstone railway station, Sydney had this arrangement, although one end has been slewed to put the platform on the straight road, and a second platform has since been provided. While the reasons for choosing this configuration seem to have been forgotten, stations using this arrangement in New South Wales at least, appear to be the more important stations, with significant townships attached.
Page 205 of 259
Up and Down working
Figure 347: Crossing Loop – Up and Down Working
Trains take the left-hand track (for example) in their direction of running. Low speed turnouts restrict the speed in one direction. Two platforms are needed and they can be island platform or two side platforms. Examples include Quakers Hill. Crossing loops using Up and Down Working are very common with British practice. For one thing, there are fewer signals if the tracks in the station are signalled for one direction only, and also there is less likelihood of a collision caused by signalling a train onto the track belonging to the opposing train. With and Up and Down loop, overtaking is not normally possible as some of the necessary signals are absent. The speed restriction in one direction can be eliminated with higher speed turnouts, but this requires power operation as the longer and heavier high-speed turnouts is beyond the capability of manual lever operation.
Simultaneous crosses and passing lanes If a crossing loop is several times the length of the trains using it, and is suitably signalled, then trains proceeding in opposite directions can pass (cross) each other without having to stop or even slow down. This greatly reduces the time lost by the first train to arrive at the crossing loop for the opposing train to go by. This system is also referred to as a dynamic loop. In the Auslink project for the Junee to Melbourne line, roughly every other section of single line will be duplicated to provide so-called passing lanes. About 220km of the 450km line will be duplicated.
Figure 348: Crossing Loop – Left Hand Working
Single ended Crossing loops are generally double ended, but occasionally a single ended siding is used for crossing purposes. Molong used to have a short crossing loop, but now a much longer length of a closed branch line (2000m) is used to cross trains. Gerringong had a single ended siding that required fly shunting to shunt.
Automatic operation New South Wales has a long history of crossing loops designed to operate automatically in an unattended mode. Some loops have the points in and out of the loop operated manually, albeit more recent examples have so-called self restoring switches that allow trains to exit a loop without needing the change the points. Other forms of remote operation included Centralized traffic control, where a train controller changes points and signals from a remote office; and driver operated points, which enable train crews to use a radio system to set the points from a distance. To reduce delays to trains by the need for the train crew to operate the points when entering the loop at basic crossing loops, ARTC is starting to equip them with Internal Crew Operated Points, which set the points at a distance and complement the self-restoring feature.
Gradients The design of crossing loops may have to be modified where there are severe gradients that make it difficult for a train to restart from a stationary position, or where the terrain is unsuitable for a normal loop. One oddity was Dombarton, New South Wales crossing loop built to divide a long single line section and located on an extreme 1 in 30 (3.3%) gradient. The “loop” was built as a miniature zigzag with the lower switchback on one side and the upper switchback on the other side, with a dive tunnel under the through-track connecting the two.
Line capacity Line capacity is determined by the spacing time-wise of the crossing loops. The longest section between successive crossing loops will, like the weakest link in a chain, determine the overall line capacity.
Page 206 of 259
Short loops It is best if all crossing loops are longer than the longest train. Two long trains can cross at a short loop using a slow so-called see-saw process.
Accidents at crossing loops
5.4.2
The legendary train driver Casey Jones was killed in an accident in 1900 involving trains too long to cross at the crossing loop at Vaughan, Mississippi. The trains trying to cross were occupying both the main and loop tracks, and in addition, the train doing the seesaw was standing outside station limits. Jones was travelling fast in order to make up lost time, and did not stop in time to avoid a collision. Exeter crossing loop collision: occurred at Exeter railway station in New South Wales, 1910s, in fog; one train too long for loop. Geurie crossing loop collision: train in loop standing foul of main line, causing collision. Violet Town railway disaster: driver dies approaching crossing loop, and goes through loop without stopping, colliding with opposing freight train. Hines Hill train collision Zanthus train collision Dugald, Manitoba April 12, 1909 – Gary, Indiana, United States: A westbound Chicago South Shore & South Bend Railroad train runs past a meet point and causes a head-on collision with the eastbound train. June 19, 1909 – Shadyside, Indiana, United States: An eastbound Chicago South Shore & South Bend Railroad train runs past a meet point and causes a head-on collision with the westbound train.
Balloon Loop
Figure 349: Double sided island platform on a balloon loop
A Balloon loop is a track arrangement that allows a train to reverse direction and return to where it came from without having to shunt or to stop.
5.4.2.1
Use
Balloon loops can be useful for passenger trains, and unit freight trains, such as coal trains. Balloon loops do not include track layouts where combinations of junctions allow a train reversal, where this reversal is not regularly used. In some transport simulators (e.g.: Transport Tycoon Deluxe, 1996 but still played worldwide), Balloon Loops are referred to as RoRo stations or Roll On, Roll Out. They are frequently used at busy stations.
5.4.2.2
Examples Passenger
Figure 350: South Ferry balloon loop
Page 207 of 259
Figure 351: Brooklyn Bridge and City Hall stations in New York City.
Olympic Park, Sydney, Australia Platforms 1 and 4 are for boarding; platforms 2 and 3 are for alighting. City Hall, New York City. USA: One platform for both boarding and alighting (now closed) South Ferry, New York City: Two tracks, two platforms (one closed) Schwabstrasse Stuttgart S-Bahn, Loop is south of the station and completely underground Bad Herrenalb, Albtalbahn, Germany: Train passes loop before arrival Dungeness railway station, Romney, Hythe & Dymchurch Railway, Kent, England. Single track, single platform for both boarding and alighting. Kennington tube station, on the London Underground Northern Line, trains from the Charing Cross branch can terminate at Kennington and then run around a loop to return north. Due to the layout, trains from the Bank branch may not access this loop. Paris Metro
Non-passenger loops: Porte Dauphine (line 2), Porte de Lilas (line 3bis), Porte de Clignancourt and Porte d'Orléans (line 4) Passenger loops: Nation (line 2), Charles de Gaulle-Etoile and Nation (line 6), Pré-Saint-Gervais (line 7bis) The western end of line 10 deserves a special mention, as it is long loop: trains arriving at Mirabeau from Gare d'Austerlitz enter a loop with a few stations on it: Eglise d'Auteuil, Auteuil, Porte d'Auteuil (official terminus), Miche-Ange Molitor, Chardon Lagache and Mirabeau again, to continue eastwards There are a few loops used for stabling trains, for example west of Invalides and north of Porte de la Villette. Tram Systems
Balloon loops are used extensively on a majority of tram systems, usually at the terminal stations. Sometimes such a loop is actually a single one-way track round a block. These loops allow use of trams with a cab at only one end and doors on one side (like a bus). Such trams are cheaper and have more space for passengers. Other tram systems have trams constructed like normal trains, with a cab at both ends and doors on both sides, so they can be used in either direction. Freight Examples from New South Wales Australia include Newnes Junction coal loader, Mount Thorley for coal, Camberwell for coal, Ulan for coal, Penny Road near Moree for wheat and Vales Point. Fassifern has triangle as well, so trains can go north or south. Newdell Junction has two balloon loops. At Bargo, due to change in operational requirements the balloon loop now points the wrong way and requires trains to be top and tailed! Other Both the French and the British terminals of the Eurotunnel Shuttle service through the Channel Tunnel consist of balloon loops.
Page 208 of 259
5.4.2.3
History
Balloon loops first appeared on railways in large numbers in the 1960s when the modernising British Rail introduced so-called merry-go-round coal trains that operated without shunting from mines to power stations and back again, around the clock. This track arrangement was introduced on metro and tram lines much earlier.
5.4.2.4
Disadvantages
The only real disadvantage of a balloon loop is that it needs a lot of space to build, and even so, the curves can be very sharp. The very sharp 180 m radius curves on the Olympic Park balloon loop cause noise, wear and tear on both the wheels and rails. Any platforms should be located on straight track, since if they are located on curved track, the gap between platform and carriage door can be a hazard.
5.4.2.5
Advantages
The advantages of a balloon loop include –
Smooth operation. Trains can arrive in any free platform, while another train is leaving any platform.
If Olympic Park station were not on a balloon loop and were a stub platform:
5.4.2.6
More tracks and platforms would be required. Arrivals into some platforms could block departures from other platforms. Time would be lost while drivers change ends and reset the train for the other direction. If the driver changed ends and discovered a hidden fault, then delays to trains would be likely.
Other Olympic stations
The Olympic station at Berlin, Germany has two through platforms and about 8 turnback platforms. This is considerably more than the 2 track / 4 platform arrangement at Sydney.
5.4.3
Headshunt (Escape Track)
A headshunt (US: escape track) is a short length of track, provided to release locomotives at terminal platforms, or to allow shunting to take place clear of main lines.
5.4.3.1
Terminal Headshunts
A terminal headshunt is a short length of track that allows a locomotive to uncouple from its train, move forward, and then run back past it on a parallel track. Such headshunts are typically installed at termini to allow the locomotive of an arriving train to move to the opposite end of (in railway parlance, 'run around') its train, so that it can then haul the same train out of the station in the other direction.
Figure 352: Platform track and run-round loop at Toyooka Station, Hyōgo, Japan, the terminus of the line from Miyazu
Page 209 of 259
5.4.3.2
Shunting neck
The term headshunt may also refer to shunting neck or shunt spur: a short length of track laid parallel to the main line for the purpose of allowing a train to shunt back into a siding or rail yard without occupying the main running-line.
5.4.3.3
Run-round
Sketch of a headshunt and run-round loop
To 'run round' is the practice of detaching a locomotive from its train, driving it to the other end of the train and re-attaching it, to allow the train to proceed in the direction it has just come from (e.g. when it reaches its destination and forms a service in the other direction). The cost (owing to the need to employ specialist staff to perform the dirty task at track level of detaching and attaching the loco, plus the dedicated track layout required) and complexity of this simple-sounding manoeuvre is one reason why loco-hauled trains are now scarce in the UK. Push-pull passenger service has also largely obviated this maneuver and the trackage required.
5.5 Yards A rail yard, or railroad yard, is a complex series of railroad tracks for storing, sorting, or loading/unloading, railroad cars and/or locomotives. Yards have many tracks in parallel for keeping rolling stock stored off the mainline, so that they do not obstruct the flow of traffic. Railroad cars are moved around by specially designed yard switchers, a type of locomotive. Cars in a railroad yard may be sorted by numerous categories, including railroad company, loaded or unloaded, destination, car type, or whether they need repairs. Railroad yards are normally built where there is a need to store cars while they are not being loaded or unloaded, or are waiting to be assembled into trains. Large yards may have a tower to control operations. There are different types of yards, and different parts of yard, depending on how they are built. Yards may have multiple industries adjacent to them where railroad cars are loaded or unloaded and then stored before they move on to their new destination.
Figure 353: Eastleigh_rail_yard_1984
Page 210 of 259
Figure 354: Badarpur Yard, Assam, India
Figure 355: Final approach over a massive rail yard immediately adjacent to O'Hare Airport, with downtown Chicago in the distance
Page 211 of 259
Figure 356: A Typical Yard (Depot)
Page 212 of 259
Figure 357: Another Yard (Depot)
Page 213 of 259
5.5.1
Marshalling Yard (Classification Yard)
A (US) classification yard or (UK) marshalling yard (including hump yards) is a railroad yard found at some freight train stations, used to separate railroad cars on to one of several tracks. First the cars are taken to a track, sometimes called a lead or a drill. From there the cars are sent through a series of switches called a ladder onto the classification tracks. Larger yards tend to put the lead on an artificially built hill called a hump to use the force of gravity to propel the cars through the ladder. Freight trains which consist of isolated cars must be made into trains and divided according to their destinations. Thus the cars must be shunted several times along their route in contrast to a unit train, which carries, for example, automobiles from the plant to a port, or coal from a mine to the power plant. This shunting is done partly at the starting and final destinations and partly (for long-distance-hauling) in classification yards. There are three types of classification yards:
5.5.1.1
Flat-shunted yards, Hump yards and Gravity yards
Flat-shunted yards
Here, the tracks lead into a flat shunting neck at one or both ends of the yard where the cars are pushed to sort them into the right track. There are many medium-sized flat yards in the USA and also some which are quite large such as (Houston-) Settegast, Decatur, East Joliet etc. In Europe several major classification yards in Italy have never had a hump, such as Verona Porta Nuova, Foggia or Villa San Giovanni (Fascio Bolano); other large European flat yards are for example Olten (Switzerland) or Valea lui Traian (Constanţa, Romania - this is an incompleted yard with 32 tracks which was planned to be a hump yard but has no hump). In Argentina all classification yards with the exception of Villa Maria are flat yards, though some of them have approx. 30 or more tracks. The world's largest classification yard is a hump yard: Bailey Yard in North Platte, Nebraska, USA. Other very large US hump yards are Elkhart Young Yard, (Chicago-) Clearing, (Kansas City-) Argentine, (Houston-) Englewood, Waycross Rice Yard etc. Specially in Europe, Russia and China, all important classification yards are hump yards. Europe's largest hump yard is that of Maschen near Hamburg, Germany; it is only slightly smaller than Bailey Yard. Most hump yards are single yards with one classification bowl but some, mostly very large, hump yards have two of them, one for each direction, thus are double yards, such as Maschen, Clearing, and Bailey yards. However, due to the transfer of freight transport from rail to road and the containerization of railfreight transport for economical reasons, hump yards are generally in decline. In Great Britain, Denmark, Norway, Japan and Australia, for example, all hump yards have already been closed.
5.5.1.2
Hump yards
Figure 358: A switch engine pushes a car over the hump (Kornwestheim classification yard (near Stuttgart, Germany) in March 2006)
Page 214 of 259
These are the largest and most effective classification yards with the largest shunting capacity — often several thousand cars a day. The heart of these yards is the hump: a lead track on a hill (hump) over which the cars are pushed by the engine. Single cars, or some coupled cars in a block, are uncoupled just before or at the crest of the hump and roll by gravity into their destination tracks in the classification bowl (the tracks where the cars are sorted). The speed of the cars rolling down from the hump into the classification bowl must be regulated because of the different natural speed of the wagons (full or empty, heavy or light freight, number of axles), the different filling of the tracks (whether there are presently few or many cars on it) and different weather conditions (temperature, wind speed and direction). As concerns speed regulation there are two types of hump yards: without or with mechanisation by retarders. In the old non-retarder yards braking was usually done in Europe by railroaders who lay skates onto the tracks, or in the USA by riders on the cars. In the modern retarder yards this work is done by mechanized "rail brakes" called retarders. They are operated either pneumatically (e.g. in the USA, France, Belgium, Russia or China) or hydraulically (e.g. in Germany, Italy or the Netherlands). Classification bowls consist of in average 20 to 40 tracks in several balloon loops, in Europe usually with eight classification tracks following a retarder in each one, often 32 tracks altogether. In the USA also many classification bowls have more than 40 tracks up to 72 which there are often divided into six to ten tracks in each balloon loop, compared with eight in Europe.
Figure 359: The retarders grip the sides of the wheels on passing cars to slow them down.
Page 215 of 259
5.5.1.3
Gravity yards
These are operated similarly to hump yards but in contrast to the latter, the whole yard is set up on a continuous falling gradient and there is less use of shunting engines. Typical locations of gravity yards are places where it was difficult to build a hump yard due to the topography. Most gravity yards were built in Germany and Great Britain, sometimes also in some other European countries, for example Łazy yard near Zawiercie on the Warsaw-Vienna Railway (originally in Russia, now in Poland). In the USA there were only very few old gravity yards; none seem to be in operation today. The largest active gravity yard is Nürnberg (Nuremberg) Rbf (Rbf: Rangierbahnhof, "classification yard"), Germany. Gravity yards also have a very large capacity but they need more staff than hump yards and thus they are the most uneconomical classification yards.
5.6 Stations 5.6.1
Station Design
The design of stations has developed over the years as the use of railways has first expanded and latterly declined. A new form of station design has also evolved with the introduction of metros and high capacity urban railways. A number of different types of station design are shown below and the advantages and disadvantages of each are discussed. On a railway which requires passengers to be in possession of a valid ticket or "authority to travel" whilst on the property, the station area is divided into an "unpaid area" and a "paid area", to denote the parts where passengers should be in possession of a valid ticket. Of course, there are now many railway operators who have "open stations", which allow passenger to wander at will without a ticket. In these circumstances, in addition to a ticket office or ticket selling machines, tickets can be purchased on the train.
5.6.2
Platform
The term platform is worth explaining. In the US, the position of a train in a station is referred to as the "track", as in "The train for San Diego is on Track 9". This is very logical as the raised portion of the ground next to the track is actually the platform and may well be used by passengers boarding a train on a track along the opposite edge of the platform. For this reason, the British way of referring to the "Train at Platform 4", referring to the platform "face", sometimes confuses foreign visitors, who see two trains, one on each side of the platform. It is a feature of station design in the UK and railways designed to UK standards, that platforms are built to the height of the train floor, or close to it. This is now also adopted as standard on metro railways throughout the world. The rest of the world has generally had a train/station interface designed on the basis that the passengers step up into the train from a low level platform or even straight off the ground. To this end, passenger vehicles were usually designed with end entrances, having the floor narrower then the rest of the car body so that a set of steps could be fitted to either side of the entrance gangway. However, high platforms are now seen in many countries around the world. Platform width is also an important feature of station design. The width must be sufficient to accommodate the largest numbers of passengers expected but must not be wasteful of space - always at a premium for station areas in expensive land districts of a city. The platform should be designed to give free visual areas along its length so that passengers can read signs and staff can ensure safety when dispatching trains. Columns supporting structures (photo) can often seriously affect the operation of a station by reducing circulating areas and passenger flows at busy times. Platform edges should be straight to assist operations by allowing clear sight lines.
5.6.3
Side platform
Figure 360: Typical Side Platform Station Layout
Figure 361: Side platforms with overpass between them
Page 216 of 259
Figure 362: Jordanhill railway station with two side platforms, and a footbridge connecting them
The basic station design used for a double track railway line has two platforms, one for each direction of travel. The series of examples in the following diagrams shows stations with right hand running as common in Europe and the Americas. Each platform has a ticket office and other passenger facilities such as toilets and perhaps a refreshment or other concession. Where there is a high frequency service or for designs with high platforms, the two platforms are usually connected by a footbridge. In the case of a station where tickets are required to allow passengers to reach the platform, a "barrier" or, in the case of a metro with automatic fare collection, a "gate line", is provided to divide the "paid area" and "unpaid area". This design allows equal access for passengers approaching from either side of the station but it does require the provision of two ticket offices and therefore staffing for both of them. Sometimes, stations with two ticket offices will man only one full time. The other will be manned as required at peak times. With side platforms, track centres remain the same, and no space is lost for slewing the track to wider centres, as would be needed for an island platform. Side platforms usually have access to neighbouring streets. The distance between the track centres (track centrelines midway between rails) is typically about 4 m, while each side platform might be 5 m wide. The use of side platforms in new train and subway stations may be severely limited if space is at a premium due to regulations regarding the minimum width of platforms.
5.6.3.1
Elevated Station with Side Platforms
Figure 363: Typical Elevated Side Platform Station Layout
Elevated railways are still popular in cities, despite their history of noise creation and generally unfriendly environmental image. The poor image has been considerably reduced with modern techniques of sound reduction and the use of reinforced and pre-stressed concrete structures. They are considerably cheaper than underground railways (at least half the price, sometimes considerably less than that) and can be operated with reduced risk of safety and evacuation problems. Modern elevated railways have been built in such cities as Miami, Bangkok, Manila and Singapore.
Page 217 of 259
5.6.3.2
Elevated Station with Ticket Hall Below Platforms
Figure 364: Elevated Station with Ticket Hall below platforms
In the example illustrated immediately above, the ticket office and gate lines are below the platform level. This can be done to allow one ticket office to serve both platforms but it requires the space to be available below track level and this, in turn, requires enough height in the structure. Since many stations are built at road intersections, the location of the station structure might have to permit road traffic to pass beneath it and this requires an adequate height structure to be built. It is sometimes better to position the structure to one side of the road intersection to allow room below for the ticket office.
5.6.4
Island (Centre) Platform
Figure 365: Typical Island Platform Layout
Figure 366: Schematic of Island Platform
Page 218 of 259
Figure 367: A station with island platform
Figure 368: Underground island platform: Clapham Common Tube Station north and south-bound platforms on the Northern Line, in London, England
A cheaper form of station construction, at least for a railway at grade level, is the island platform. As its name suggests, this is a single platform serving two tracks passing on either side, effectively creating an island which can only be accessed by crossing a track. A bridge or underpass is usually provided. Island platforms are usually wider than single platforms used for side platform stations but they still require less area. In the example shown above, there are two ticket offices, but one can be provided if preferred. Island platforms on elevated railways do require additional construction of the viaduct structure (usually adding considerably to the costs) to accommodate the curves in the tracks needed to separate them on the approach to the platform. An island platform on a railway is where a single platform lies between two tracks, serving both of them. Usually, the two tracks are on the same line, running in opposite directions. One station may have two island platforms in a four-track express configuration; in this case, each platform may serve trains in one direction, with local and express trains stopping on opposite sides of a single platform.
Page 219 of 259
5.6.4.1
Advantages and tradeoffs
Island platforms generally have a lower construction cost and require less space than side platforms, a pair of separate platforms with the tracks running between them. However, island platforms may become overcrowded, especially at busy stations. Additionally, the need for the tracks to diverge around the centre platform requires extra width along the right-of-way on each approach to the station, especially on high-speed lines. Track centres vary from rail systems throughout the world, but are normally about 4 meters (13 ft). If the island platform is 6 meters (20 ft) wide, the tracks have to slew out by the same distance. A common configuration in busy locations on high speed lines uses a pair of island platforms, with slower trains diverging from the main line so that the main line tracks remain straight. High-speed trains can therefore pass straight through the station, while slow trains pass around the platforms. This arrangement also allows the station to serve as a point where slow trains can be passed by faster trains. Island platforms are popular in the modern railway world for several reasons. One is their lower construction cost. Island platforms also allow facilities such as escalators, elevators, shops, toilets and waiting rooms to be shared between both tracks rather than being duplicated or present only on one side. Passenger convenience is another significant consideration. Generally, even able-bodied passengers dislike climbing steps to pass between platforms, and in some areas subways under the railway line may also pose vandalism and security problems. A growing consideration is the requirement for wheelchair accessible stations. An island platform makes it easier for wheelchair users and the infirm to change services. The historical use of island platforms depends greatly upon the location. In the United Kingdom the use of island platforms is relatively common when the railway line is in a cutting or raised on an embankment, as this makes it easier to provide access to the platform without walking across the tracks. Many of the stations on the Great Central Railway (now closed) were constructed in this form.
5.6.5
Bay platform
Figure 369: A bay platform at Nottingham railway station
A bay platform is a railway-related term commonly used in Britain and Australia to mean a dead-end platform at a railway station which otherwise consists exclusively (or predominantly) of through platforms.
5.6.5.1
Overview
An example of a station which has a bay platform is Rugby railway station, which has two through platforms and two working bay platforms, as well as 2 abandoned bay platforms. Trains which use a bay platform have to reverse direction and depart in the direction from which they arrived. Bay and island platforms are so named because they resemble the geographic features of the same name.
5.6.5.2
Dock platforms
Dock platforms are similar to bay platforms, but are smaller, and originally used to unload freight.
Page 220 of 259
5.6.6
Terminal Station Platform
A terminus or terminal station refers to the termination of the railway line or service at that point. All |platforms may be accessed without having to cross the |rail tracks. This may not be true if the station yard lies behind the passenger station, but in this case the station may not strictly be regarded as a terminus. The largest and most famous rail terminal in the United States is Grand Central Terminal in New York City, USA. Often major cities, such as London, Boston, Paris or Milan will have one or more termini, rather than routes straight through the city. Train journeys through such cities often require alternative transport (metro, bus or taxi) from one terminus to the other. Some cities, including New York, have both situations. Chicago has four major rail terminals presently in service, of which only one provides Amtrak intercity service (see Rail stations of Chicago). A terminus is usually the final destination of trains serving the station, but this is not always the case. Where the terminus is an intermediate point on a train's itinerary, the train must leave in the reverse direction from that of its arrival. There are several ways the train may be reversed: the railway operator may use a multiple unit, or push-pull train which can operate in either direction; use two locomotives, one at each end; or the locomotive which brought the train into the station must detach from its train and either 'run around' to the other end of the formation or be replaced at the other end by another locomotive, which takes the train out.
5.6.7
Spanish Solution (Barcelona Solution)
Spanish solution (also called Barcelona solution) is a method of using two platforms, on both sides of the track, by one train to speed up embarkation and disembarkation: passengers get off the train on one side, and get on from the other. Usually there are three platforms (one island platform and two side platforms) shared between two tracks. Passengers may be required to embark from one side and disembark from the other, or both may be permitted on both sides of the train. The principle was used in Europe for the first time in Spain on the Barcelona metro (hence the name) in the 1930's. However, this solution was used earlier (1913) at Chambers Street station on the New York City Subway.
Figure 370: The Principle of the Spanish Solution
Page 221 of 259
5.6.8
Cross-platform interchange
A cross-platform interchange is a type of interchange between different lines in a metro system. The term originates with the London Underground; such layouts exist in other networks but are not commonly so named. In the United States, it is referred to as simply a "transfer". It occurs in a system with island platforms, a single platform in between the two directions of travel, or two platforms between the tracks, connected by level corridors. In a cross-platform interchange, instead of the two opposite directions of a single line sharing an island platform, two similar directions of two different lines share it.
5.6.8.1
Examples
In London's deep-level tube network, these usually occur in pairs for both directions of two lines. This allows for extremely quick and convenient interchange. Such example stations includes Finsbury Park (Piccadilly and Victoria Lines and Euston station (Northern and Victoria Lines). The effect is that the two lines, despite having completely separate operation, can be treated by passengers as branches of a single network. The Mass Rapid Transit system in Singapore features a similar two-station transfer arrangement to allow quick transfers between North South and East West lines. Both City Hall MRT Station and Raffles Place MRT Station feature double underground island platforms stacked atop the other, allowing commuters to switch trains to any direction by walking across the same platform or access the other platform via escalators. Jurong East MRT Station has a less complicated arrangement, with the terminating rail for the North South line aligned between that of the East West line, allowing commuters to alight and board simultaneously on either side. Hong Kong's Mass Transit Railway is another example, with the majority of its interchange stations being of the cross-platform design. In addition, three of its stations feature an inverse cross-platform interchange, which allow passengers travelling in opposite directions to change trains without leaving the island platform.
Figure 371: A diagram of how a paired cross-platform interchange works
Figure 372: Passengers interchange (between the Central Line and 'one' train service at Stratford station in London, England.)
Page 222 of 259
5.6.9
Platform Screen Doors
Figure 373: Platform screen (edge) doors are provided on the Jubilee Line stations. The operation of the doors is synchronised with those on the train. Here the driver aligns the train with the doors to within +/- 250 mm in order for the doors to open, though in most modern cases the doors are automatically aligned.
Figure 374: Platform screen doors at Serangoon MRT Station in Singapore’s North East Line
Page 223 of 259
There has been a trend recently in modern metro systems towards incorporating glazed screens along platform edges. This is only possible where sliding powered doors are available on trains and where the location of these doors is always consistent, which is why screen doors do not appear on main line railways. There are a number of interesting points to remember when considering platform screen doors. Platform screen doors (sometimes called "platform edge doors") were first introduced in St Petersburg (then Leningrad) on the metro to reduce heat losses on station platforms of underground stations. They were also fitted to the Lille VAL driverless system but, in this case, as a way of preventing passengers from getting onto the line where there were no drivers to stop the train. It too allowed a better degree of climate control within stations. Climate control was also the reason why doors were introduced for underground stations in Singapore when its metro system was started in 1989. On most lines equipped with platform screen doors, the space between the sliding doors has emergency doors that can be pushed open onto the platform, so if the train stops out of position, there is still emergency access to the platform. There are also local station door controls provided at the platform ends, in case the automatic system fails. London Underground has introduced doors on the underground platforms of its new Jubilee Line extension. These are more for safety reasons, since the suicide rate in London has gone as high as 150 attempts in some years. At somewhere around USD 1.5 million a platform, these doors are not cheap but the savings in passenger time due to prevention of delays quickly justifies the expense on a socio-economic level, even if you choose to ignore the savings in human life. Above is a photo of the doors at the new Canary Wharf station (Jubilee Line) in London. Against the provision of platform doors must be the cost of maintenance. Train doors account for more than half the rolling stock failures of most metro and suburban railways and the same sort of designs are used for platform doors. Any system that uses such doors must ensure that adequate provision for maintenance is made and that any savings in heating or ventilation costs is not outweighed by failures. In Lyons, France, the MAGGALY driverless automatic metro Line D has no platform screen doors. Instead the platform track areas are equipped with a network of electronic detector beams which trigger the train stop commands if a beam is broken. When it was first installed, there were so many false alarms that an alarm to the control centre now allows the operating staff to observe the area through CCTV before confirming the stop command. State-of-the-art platform screen doors can be seen at the Singapore North East Line MRT.
5.6.10 Passenger Information Displays Information systems (photo left) on stations are variously referred to as a Passenger Information System (sometimes referred to as PIS) or Passenger Information Display (PID). Professional railway staff often refer to them as Train Describers. Whatever it is called, there must be a reliable way of informing the passengers where the trains are going. Passenger information systems are essential for any railway. One of the most common complaints by passengers on railways is the lack of up to date and accurate information. When asking the staff for information, passengers expect an accurate and courteous response with the latest data. There is nothing worse than the "your guess is as good as mine" response when a member of staff is asked what is happening when a train is delayed or has not appeared on time. This means that staff must have access to the latest information and they must be trained to use it properly and to pass it on to passengers. Information displays mounted in public areas must be visible in all weather conditions (noting that some electronic displays are very difficult to see in sunlight conditions) and be updated regularly with accurate information. There are two types of information - constant and instant. Constant information can be described as that which describes the services and fares available and which changes only a few times a year or less. This information can be displayed on posters and fixed notices. There also might be special offers, which can be posted from time to time. Instant information is that which changes daily or minute-by-minute. This is better displayed electronically or mechanically - both systems can be seen around the world. For instant systems, it can be assumed that passengers require to know:
The time now The destination and expected time of arrival of the next train The stations served by this train Major connections requiring boarding of this train The position of their car - if travelling with a reserved place Where the train will stop - for variable length trains Other destinations served from this station and from which platform
A good example of passenger information displays can be seen on some Paris (France) RER stations. A large illuminated board is hung over the platform and all the stations served by the train approaching are shown by lamps lit next to the station name. The time now and the train length is also shown. Although the system is not now modern, it is very effective. There are some information systems appearing with advertising in some form or other. This is a useful source of revenue or sponsorship but it must not be allowed to detract from the main aim of providing the passenger with train service information. Some modernised lines are nowadays provided with bi-directional signalling. This allows trains to travel along either line at normal speeds and be fully under the control of fixed signals. This is a useful facility to have when engineering works have made one track unusable. Trains operating in either direction will then use the other track(s). For passenger information purposes, bi-directional signalling makes it necessary to have good and easily variable passenger information displays.
Page 224 of 259
5.7 Hill Climbing 5.7.1
Horseshoe curve
As far as possible, a railway trying to climb a steep gradient tries to follow the contours so that cuttings and embankments are kept to a minimum, while also minimizing the total length of the line.
Figure 375: Satellite view of Horseshoe Curve, west of Altoona, Pennsylvania. Trains headed counterclockwise around the curve are going uphill.
Figure 376: Panorama of the Pennsylvania Railroad's Horseshoe Curve
Sometimes a valley at right angles to the general direction of travel can be used to create a contour hugging "horseshoe curve".
5.7.1.1
5.7.2
Examples of horseshoe curves Horseshoe Curve (Pennsylvania), at Kittanning Gap Dunsmuir, California has a pair of horseshoe curves nearby. Map Cascade Tunnel has a gully on the western approaches that is an unnamed horseshoe curve. Dovrebanen, the main line of Norwegian railway network, has a horseshoe from Dombås up to the Dovre plateau. Raumabanen, has a double horseshoe with a tunnel at Verma downhill from Dombås.
Zigzags (Switchbacks)
A railway Zigzag is a way of climbing hills in difficult country with a minimal need for tunnels and heavy earthworks. For a short distance (corresponding to the middle leg of the letter "Z"), the direction of travel is reversed, before the original direction is resumed. Zigzags are often an alternative to a spiral though these may require long tunnels. In the United States, zigzags are called switchbacks.
5.7.2.1
Advantages
The advantages of a zigzag include speed and low cost of construction with no need to worsen the ruling grade compared to the alternative, which almost certainly will require tunnels, which are slow and costly to build. Where traffic is modest, a zigzag may well be a sensible long-term solution.
5.7.2.2
Disadvantages
Zigzags suffer from a number of possible limitations:
The length of a train will be limited by length of track at the top and bottom points. Reversing a train without running an engine around to the rear of the train is hazardous. Engines at the rear of the train help. The process is slow.
Page 225 of 259
5.7.2.3
Locations of zigzags Argentina
Tren a las Nubes Australia
Kalamunda Zigzag - 2 reversals Lapstone Zigzag - 2 reversals Lithgow Zigzag Mundaring Weir Branch Railway Germany
Zigzags in use:
Rauenstein (railway-line: Hinterlandbahn) Lauscha (railway-line: Sonneberg – Probstzella) Ernstthal am Rennsteig: created by close of the railway-line: Ernstthal–Probstzella Rennsteig (railway-line: Rennsteigbahn, Ilmenau – Themar) Michaelstein (railway-line: Rübelandbahn) Wurzbach (railway-line: Saalfeld – Blankenstein)
Zigzags out of use:
Schillingsfürst (dismantled) Lenzkirch in the Blackforrest (dismantled) Elm (replaced in 1914 by Distelrasen-Tunnel, but the structure is conserved within the railway-lines Frankfurt am Main - Fulda, Fulda Gemünden and the connecting curve between the stations Elm and Schlüchtern) Railway-line Steinhelle-Medebach (double zig zag) Railway station Mainspitze in Frankfurt am Main, 1846 - 1848 to reach the provisional Frankfurt terminal of the Main-Neckar-Eisenbahn Erdbach-Station, Westerwaldquerbahn Pakistan
Khyber Pass India
Darjeeling Himalayan Railway has six full Zigzags. The gauge is narrow gauge. Japan Hakone Tozan Line has three Zigzags. Tateyama Erosion Control Tramway - 38 Zigzags, 18 in a row. South Korea
Yeongdong Line, between Heungjeon and Nahanjeong stations to be closed in 2009; replace by new tunnel. Peru
Cacray Zigzag on the Central Railway of Peru - with 9 switchbacks Peru Rail between Cuzco to Machu Picchu - 5 switchbacks Taiwan
Alishan Forest Railway United States
8 Switchbacks at Cascade on GN - replaced by tunnel which was in turn replaced by a longer tunnel.
Page 226 of 259
5.7.3
Spiral
A spiral (sometimes called a spiral loop) is a technique employed by railways to ascend steep hills. The railway spiral involves a track which rises on a steady curve until it has completed a 360-degree loop, passing over itself as it gains height. This allows the railway to gain vertical elevation in a relatively short horizontal distance. It is an alternative to a zigzag, and avoids the need for the trains to stop and reverse direction while ascending. If the train is of sufficient length, it is possible to view the train looping onto itself. A spiral loop should not be confused with the civil engineering spiral curve used to provide a transition from a tangent into a horizontal circular curve. The civil engineering spiral curve is a curve of uniformly decreasing radius (beginning at infinite and ending at the radius of the circular curve) used to minimize rolling stock sway and also in highway curves for aesthetic reasons.
Figure 377: A Spiral
Figure 378: Loop (Agony Point) on the Darjeeling Himalayan Railway, India
Page 227 of 259
5.7.3.1
Calculations
Consider a railway climbing at a gradient of 1 in 40 (2.5%, or 25 m per km). A 360-degree spiral at 350 m radius will add 1100 m to the forward journey and 27 m to the vertical climb. Unless the topography has a suitably shaped hill, the spiral is likely to be in tunnel, creating problems if steam locomotives are employed. The spiral needs to climb about 6 m in order to bridge itself. With steam locomotives and to a lesser extent with diesel locomotives, the gradient in the tunnel should be less than the ruling grade to avoid problems with fumes and dampness causing the driving wheels to slip.
5.7.3.2
Examples of Spirals Africa
Kenya-Uganda four spirals on the Kenya to Uganda line. Australia
Bethungra Spiral: two very short tunnels, downhill track plain at 1 in 40 gradient, uphill track in spiral at 1 in 66 gradient Cougal Spiral one short, one long tunnel, single track Bulgaria
Avramovo 760 mm (2 ft 59⁄10 in) gauge Canada
Spiral tunnels between Field, BC, and the summit of Kicking Horse Pass, Canadian Pacific Railway France
Sayerce tunnel between Pau (France) and Zaragossa (Spain) in the Pyrenees [1] The railway between Nice (France) and Cuneo (Italy) use three spirals. Germany
Rendsburg Viaduct, southern approach. Unique oblong single loop onto the transporter bridge crossing Kiel Canal The Wutachtalbahn had to be built less steep than possible to haul heavy military trains over it, since it was the bypass for the shorter route Singen–Waldshut, which crossed Swiss territory. India
Darjeeling Himalayan Railway (DHR) has three (originally five) loops, of which one is a double spiral. ft (610 mm) gauge on metre gauge line, between Khandwa and Hingoli. Iran
Numerous spirals through very mountainous regions, mostly entirely in tunnel and single track Ireland
The St. James's Gate Brewery, Dublin had an internal 1 ft 10 in gauge railway with a loop in a tunnel to gain height between buildings Japan
Joetsu Line has two spirals, track towards Tokyo only Hokuriku Main Line between Tsuruga and Shinhikita Hisatsu line Tosa Kuroshio Railway Nakamura line Yurikamome, western approach to the Rainbow Bridge Madagascar
One loop at Anjiro on the main line from Antananrivo to Toamasina
Page 228 of 259
Myanmar
Two spirals on the Burmah Mines Railway New Zealand
Raurimu Spiral on the North Island Main Trunk, single track, suitable hill, two short tunnels Norway
Flåmsbana: between Myrdal and Flåm - tunnels that spiral in and out of the mountainside Slovakia
Telgart Loop (Telgártská sľučka) South Korea
between Bangok station and Chiak station on Jungang Line - one loop, single track. New double track tunnel is under construction. between Jungnyeong station and Huibangsa station on the Jungang Line - one loop, single track. Spain
Cargol Tunnel on the Ripoll - La Tour de Carol (France) line Switzerland
Gotthardbahn has five spirals and two turns, entirely in tunnel, double track, standard gauge Albulabahn has several spiral tunnels, single track, metre gauge RhB has an open spiral mainly on a bridge (Berninabahn, near Brusio), single track, metre gauge Heritage railway Dampfbahn Furka-Bergstrecke, has one on top, single track, metre gauge, catenary removed Matterhorn-Gotthard-Bahn (Furka-Oberalp-Bahn), between Grengiols and Laax, single track, metre gauge, cog rail, entirely in tunnel Taiwan
Dulishan loop is a triple spiral (two clockwise and one counter-clockwise) Alishan (阿里山) Forest Railway, narrow gauge, single track United Kingdom
Dduallt Loop, Ffestiniog Railway in Wales, 1 ft 111⁄2 in (597 mm) gauge The line from Moorswater cement terminal, through Coombe Junction and Liskeard on the Looe Valley Line and on over Moorswater Viaduct forms a complete spiral, climbing up to join the main line at Liskeard. However, not all of this are used for passenger working.
5.8 Buffer Stop 5.8.1
What is!
A buffer stop or bumper (US) is a device to prevent railway vehicles from going past the end of a section of track. The design of the buffer stop depends in part on the kind of couplings that the railway uses, since the coupling is the part of the vehicle that the buffer stop first touches. The term buffer stop is a British term as railways in Britain use buffer and chain couplings.
Figure 379: A buffer stop
Page 229 of 259
Figure 380: This southerly view (10/8/06) shows the temporary buffer stop and loop at Traeth Mawr at the end of the 900m Extension from Pen-y-Mount. The point lever at this end remains to be fitted.
Figure 381: 47972 stands at the buffer stops at London St Pancras after arriving with a HST replacement service on 04/01/93, the train was the 1523 ex Sheffield.
Page 230 of 259
Figure 382: At Queensland Railways maintenance yard at Banyo the siding comes to an end at the buffer stop.
Page 231 of 259
Figure 383: Two views of a Hayes-built bumper at the Linden Railroad Museum, Linden, Indiana.
5.8.2
Energy-absorbing buffer stops
The large mass of a train, even at low speed, transfers a large amount of energy in a collision with a buffer stop. Ordinary buffer stops cannot cope. What is needed is some way of dissipating this energy, as through hydraulics or friction. Following a buffer stop accident at Frankfurt-am-Main in 1902, the Rawie company developed a large range of energy-absorbing buffer stops. Similar hydraulic buffer stops were developed by Ransomes & Rapier in the UK. Lower cost alternatives to a buffer stop include railroad ties fixed to the rails, or a pile of dirt.
Figure 384: Energy-absorbing buffer stop in France
Page 232 of 259
Figure 385: Buffer stop at Zurich Main Station track 54. The buffer stop is designed to move up to 7 m to slow down a 850 t passenger train from 15 km/h without damaging the train or injuring passengers.
5.8.3
Warning lights
Buffer stops often have a fixed red light associated with them.
Page 233 of 259
5.8.4
Accidents
Figure 386: The aftermath of the Gare Montparnasse accident
October 22, 1895 – Gare Montparnasse, Paris, France: express train overruns buffer stop and falls into street below 1902 – Frankfurt am Main, Germany: Serious buffer stop collision inspires development of Rawie range of energy-absorbing buffer stops. 27 July 1903; Glasgow St Enoch, 16 killed 27 injured 1948 - diesel train through buffer stops at Los Angeles 1970s - BART train went through buffer stops due to fault in ATO. 28 February 1975 - Moorgate Underground rail crash, 43 killed, 74 injured - buffer stop collision made far worse by dead end tunnel November 8, 1986 – Hua Lamphong, Bangkok, Thailand: 5 killed, 7 injured - buffer stop collision made by an unmanned train at a speed of 50 km/h. 8 January 1991 - Cannon Street station rail crash, London; 2 killed, 200+ injured - commuter train hits buffer stops 11 July 1995 - Largs - electric train went through buffer stops. 26 October 2006 - Kuala Lumpur buffer stop accident - a Star LRT train went through the buffer stops and dangled over the street.
Page 234 of 259
5.9 Level Crossing 5.9.1
What is!
Figure 387: An automatic level crossing in France, with half-barriers, flashing lights and a bell.
Figure 388: A fence or chicane may prevent pedestrians running across the track
Page 235 of 259
Figure 389: Flangeway timber road crossing
The term level crossing (also called a railroad crossing, railway crossing, train crossing or grade crossing) is a crossing on one level (“at-grade intersection”) without recourse to a bridge or tunnel of a railway line with a road or another railroad. It also applies when a light rail line with separate right-of-way (or a reserved track tramway) crosses a road.
5.9.1.1
Safety
Early level crossings had a flagman in a nearby booth who would, on the approach of a train, wave a red flag or lantern to stop all traffic and clear the tracks. Manual or electrical closable gates that barricaded the roadway were later introduced. The gates were intended to be a complete barrier against intrusion of any road traffic onto the railway. In the early days of the railways much road traffic was horsedrawn or included livestock. It was thus necessary to provide a real barrier. Thus, crossing gates, when closed to road traffic, crossed the entire width of the road. When opened to allow road users to cross the line, the gates were swung across the width of the railway, preventing any pedestrians or animals getting onto the line. The first U.S. patent for such crossing gates was awarded on August 27, 1867, to J. Nason and J. F. Wilson, both of Boston, Massachusetts. With the appearance of motor vehicles, this barrier became less and less effective and the need for a barrier to livestock diminished dramatically. Many countries therefore substituted the gated crossings with less strong but highly visible barriers and relied upon road users following the associated warning signals to stop. In many countries, level crossings on less important roads and railway lines are often "open" or "uncontrolled", sometimes with warning lights or bells to warn of approaching trains. Ungated crossings represent a safety issue; many accidents have occurred due to failure to notice or obey the warning. Railways in the United States are adding reflectors to the side of each train car to help prevent accidents at level crossings. In some countries, such as Ireland, instead of an open crossing there may be manually operated gates, which the motorist must open and close. These too have significant risks, as they are unsafe to use without possessing a knowledge of the train timetable: motorists may be instructed to telephone the railway signaller, but may not always do so. The consensus in contemporary railway design is to avoid the use of level crossings. The director of rail safety at the UK Railway Inspectorate commented in 2004 that "the use of level crossings contributes the greatest potential for catastrophic risk on the railways." Eighteen people were killed in the UK on level crossings in 2003-4. Bridges and tunnels are now favoured, but this can be impractical in flat countryside where there is insufficient space to build a roadway embankment or tunnel (because of nearby buildings). At railway stations a pedestrian level crossing is sometimes provided to allow passengers to reach other platforms in the absence of an underpass or bridge. Where third rail systems have level crossings, there is a gap in the third rail over the level crossing, but the power supply is not interrupted since trains have current collectors on multiple cars.
Page 236 of 259
5.9.1.2
Crossings around the world Australia
In Melbourne, Australia, there are several level crossings where the train tracks cross roads with tram tracks. Australian railroading generally follows United States practice, and has increasingly been employing American-made crossing warning equipment, such as grade crossing predictors, which attempt to provide a consistent amount of warning time for a trains of widely varying speeds. One recent innovation in Australia is to provide crossbucks with flashing yellow lights at a distance from the level crossing itself, particularly where there are curves and visibility problems. Belgium At a level crossing, any overhead electric power cables must also cross. This led to a conflict where a mainline railway that crossed one of the country's once extensive interurban tramlines was electrified. In at least one location, this led to the tram overhead being dismantled. Automatic Level crossings in Belgium, have two red lights, an amber light and sometimes barriers. However, the amber flashes for a second every certain number of seconds just to inform drivers and pedestrians that they don't need to check if a train is coming, if the amber light is absent you proceed at your own risk. Canada Grade crossing protection practices in Canada are virtually identical to those in the United States using the same alternating flashing red lights and gate arms. The only significant differences are the crossbucks, which have no wording but are white with a red outline, and the advance-warning sign, which is a yellow diamond shape with a diagram of a track crossing a straight segment of road (similar to a crossroads sign, except that the horizontal road is replaced by a track). Before changes in regulations mandated bilingual (English and French) or no-wording signs, crossbucks were nearly identical to those in the states, except that they read "Railway Crossing" instead of "Railroad Crossing." Italy The cable-hauled section of the tramway up the hill from Trieste to Opicina has an interesting level crossing with a minor road at midpoint. As well as the rails, people crossing have to step or drive over two haulage cables, separated by wooden planking. New Zealand On the Taieri Gorge line, and in two places on the Hokitika Branch, in rural South Island, roads and railways share the same bridge when crossing a river; the rails are in the road and both motorists and the train driver must ensure that the bridge is clear, end-to-end, before starting to cross. Southeast Asia Level crossings in China, Thailand, and Malaysia are still largely manually-operated, where the barriers are lowered using a manual switch when trains approach. A significant number of crossings are without barriers. Taiwan As most railways in Taiwan were built during Japanese administration, railway level crossings remain very common, though many urban crossings have been eliminated when the railroads have been moved underground, e.g., segments of the Western Line in Taipei City, or abolished, e.g. the former Danshui TRA Line that is now the DanShui Line of the Taipei Rapid Transit System with no level crossings. The Act Governing the Punishment of Violation of Road traffic Regulations defines railway level crossing violations as:
Not obeying a direction of a flagman or insisting to cross when the gate starts lowering or when the bell rings or the (alternate red) lights flash. Directly crossing a railway level crossing not guarded by any flagman, gate, bell, or flashing light equipment without stopping as required when a warning sign is present. Overtaking, turning around, backing up, stopping or parking on a railway level crossing (applicable to drivers of motorized and nonmotorized vehicles but not pedestrians).
The same Act provides different penalties against different types of railway level crossing violators as follows, with very heavy penalties against motorists and lighter penalties against bicyclists and pedestrians:
Article 54: A driver of a motor vehicle shall be administratively fined 6000 to 12000 new Taiwan dollars for a railroad crossing violation. Should an accident occur, the driver license shall also be revoked, which is for life pursuant to Article 67. This lifetime revocation used to be absolute, but the amendment of the law proclaimed on 28 December 2005 and effective on 1 July 2006 has allowed a possible waiver after serving at least 6 years of the revocation. Article 75: A driver of a non-motorized vehicle (e.g., a bicycle) shall be administratively fined 1200 to 2400 New Taiwan dollars for a railroad crossing violation. Article 80: A pedestrian shall be fined 1200 New Taiwan dollars for a railroad crossing violation.
Page 237 of 259
Accidents at railway level crossings remain a very serious concern. The Taiwan Railway Administration alone has hundreds of level crossings along its routes of slightly more than 1100 km. In average, there is a level crossing in less than 2 km. Red emergency buttons have been installed to allow the public to report an emergency at a level crossing, such as stalled vehicles or any obstacles that would be very dangerous should any train approach. However, wilfully misusing the emergency button is a criminal offence. In an emergency, the public is asked to:
First, press the button and be sure of its activation with a flashing light. Second, try to clear any obstacles, including any vehicles. Third, if unable to clear the obstacles and the warning bell rings, leave quickly. "A train is coming and please quickly leave the level crossing" will be announced in Mandarin, Taiwanese and Hakka. United Kingdom
A level crossing sign on the Romney, Hythe and Dymchurch Railway at St Mary's Bay railway station, UKThere are 8200 level crossings remaining in the United Kingdom in 2005. Of these, 1600 are road crossings. This number is gradually being reduced as the risk of accident at level crossings is considered high. The director of the Health and Safety Executive commented in 2004 that "the use of level crossings contributes the greatest potential for catastrophic risk on the railways."[5] Bridges and tunnels are now favoured, and there is a commitment on the part of UK rail authorities not to build new level crossings, and to reduce the number of existing level crossings. The cost of making significant reductions, other than by simply closing the crossings, is substantial, and a number of commentators argue that the money could be better spent. Some 6500 crossings are user-worked crossings or footpaths with very low usage. The removal of crossings can also improve train performance as some crossings have low rail speed limits enforced on them to protect road users. In November 2004 there were two major accidents on UK level crossings: one involved a car driver suspected of committing suicide, who caused the death of seven people (Ufton Nervet rail crash); another involving a train carrying 50 school children resulted in no fatalities but a number of injuries. These incidents have increased efforts to review the placing of level crossings and to eliminate them where this is practicable. In the UK it has also been suggested that cameras similar to the type used to detect drivers who run traffic lights be deployed at level crossings, and that penalties for ignoring signals should be much more severe. A particular problem has been that the responsibility for the road safety at crossings is entirely outside the control of the railways. In 2006 legislative activities are in progress to permit Network Rail to be involved in the roadside safety of crossings. This will allow the introduction of anti-slip surfaces and also barriers to prevent motorists driving around crossing arms and, it is hoped, reduce the number of crossing related deaths. In the United Kingdom, major crossings were normally situated within easy viewing distance of a signal box, and usually directly adjacent to the signal box. This ensured that the signalman could verify that the road was clear before allowing a train onto the crossing. Many gated crossings have been replaced by lifting barriers, which are easier to mechanise. "Full barriers" consist of barriers each side of the track, which block the full width of the road and "half barriers" consist of a single arm each side of the road, which block only oncoming traffic. Half barriers were considered to have an advantage as motorists are less likely to be stranded on the crossing and unable to exit, but cases where impatient motorists have driven around the barriers have raised safety concerns. Video cameras are now often used at crossings to allow the human operator to be some distance from the crossing. On lightly-used railways many crossings are sited next to station stops or other stopping points and are crew operated. The guard pushes a plunger on a control box and the barriers are lowered. Once lowered an indicator light permits the driver to proceed if the crossing ahead of is clear. After the train has cleared the crossing automatic control equipment raises the barriers. To ensure that the barriers are noticed and to draw attention, public road crossings are fitted with a ringing warning bell or siren and with lights. Each crossing point also has a telephone, which connects to the local signal box so that in the case of an emergency the signalman's attention can be drawn promptly to the hazard and action can be taken. Some "automatic open crossings", with warning lights and bells but no barriers, were introduced, but their expansion was largely halted after the Lockington rail crash. Some smaller crossings, particularly pedestrian crossings on low-speed lines consist of nothing but a warning sign and raised pathway across the track itself. The use of pedestrian crossings at stations is now rare, although historically it was common that passengers walked across the line between platforms on branch lines. At Settle, for example, before the footbridge was installed in the 1990s, the time taken while passengers from Leeds walked across the line was happily used to top up the driver's kettle with hot water. With a few exceptions, such as at Carmarthen, the remaining examples occur only on heritage railways. United States In the United States and in countries following U.S. practices, a locomotive must have a bright headlight and ditch lights (short-throw bright lights located below the headlight), a working bell, and a whistle or horn that must be sounded four times (long-long-short-long, or the letter Q in Morse code) as the train approaches the crossing. Some American cities, in the interest of noise abatement, have passed laws prohibiting the sounding of bells and whistles; however, their ability to enforce such rules is debatable. In December 2003, the U.S. Federal Railroad Administration published regulations that would create areas where train horns could be silenced, provided that certain safety measures were put in place, such as concrete barriers preventing drivers from circumventing the gates or automatic directional whistles (also called wayside horns) mounted at the crossing (which reduce noise pollution to nearby neighbourhoods). Additional information can be found at the FRA website under "Train horn rule." Implementation of the new "Quiet Zone" Final Rule was delayed repeatedly but was finally implemented in the summer of 2005. All crossings in the United States are required to be marked by at least a crossbuck; most crossings that intersect rural roads have this setup. In the event that the crossing contains more than one railroad track the crossbuck will usually have a small sign below denoting the number of tracks at the crossing. As traffic on the road crossing or the rail crossing increases, safety features are increased accordingly. More heavily trafficked crossings have automatic warning devices (AWDs), which feature alternately flashing red lights to warn automobile drivers and a bell to warn pedestrians.
Page 238 of 259
Additional safety is attained through crossing gates that block automobiles' approach to the tracks when activated. Increasingly, crossings are being fitted with four-quadrant gates to prevent circumventing the gates and crossing the tracks. Operation of a typical AWD-equipped railroad crossing in the United States is as follows:
Approximately 30 seconds before arriving at the crossing, the train trips a track circuit near the crossing, triggering the crossing signals. The lights begin to flash alternately, and a bell mounted at the crossing begins ringing. After several seconds of flashing lights and ringing bells, the crossing gates (if equipped) begin to lower, which usually takes 5-10 seconds. Some AWDs will silence the bell once the gates are fully lowered; others continue ringing the bells throughout. The lights continue to flash throughout regardless. Approximately 15 to 20 seconds before arriving at the crossing, the train begins ringing its engine bell and sounds its horn in accordance with NORAC rule 14L or GCOR rule 5.8.2(7): two long blows, one short blow, and one long blow. This signal and engine bell ringing is prolonged or repeated until the engine occupies the crossing. If the AWD is equipped with a directional horn in accordance with FRA Quiet Zone rules, the AWD may provide the whistle signal instead of the train; however, the engine is required to ring its bell regardless. After the train has cleared the crossing, the gates (if equipped) begin to rise, and the bells (if silenced) may begin ringing again. Once the gates have completely risen back to their fully raised position, all warning signals, including the lights and bells, are deactivated. Some AWD track circuits are equipped with motion detectors that will deactivate the crossing signal if the train stops or slows significantly before arriving at the crossing. As indicated above, the pattern of the bells at each individual crossing can be different. (These bells should not be confused with the bells that are mounted on the trains themselves.) Generally, the bells follow one of these patterns: The bell begins ringing when the lights begin flashing and ringing ceases when the gates have completely lowered. The bell begins ringing when the lights begin flashing and ringing ceases when the gates begin to go up (following the passing of the train.) The bell begins ringing when the lights begin flashing and ringing temporarily stops when the gates have completely lowered. However, when the gates begin to rise, the bell begins ringing again, and rings until the gates have returned to their original position. The final, and most simple, practice is for the bells to begin ringing when the lights begin flashing, keep ringing after the gates have completely lowered, and continue ringing while the gates are rising, only to cease when they have risen completely back to their original position.
A handful of level crossings still use wigwag signals, which were developed in the early 1900s by the Pacific Electric Railway interurban system in the Los Angeles region to protect its many level crossings. Though now considered to be antique, around 100 such signals are still in use, almost all on branch lines. By law, these signals must be replaced by the now-standard alternating red lights when they are retired. A special kind of crossing sign assembly was introduced on an experimental basis in Ohio in 1992, the "Buckeye Crossbuck". It includes an enhanced crossbuck, reflective and with red lettering, and also a reflective plate reading "YIELD" below the crossbuck, whose sides are bent backwards in order to catch and reflect at a right angle the light of an approaching train. The experiment's final report ("Evaluation of the Buckeye Crossbuck at Public, Passive Railroad/Highway Grade Crossings in Ohio", Ohio Department of Transportation State Job Number 14612, December 2000) gave the device a favourable review. However, the plate was rejected for inclusion in the 2003 Manual on Uniform Traffic Control Devices. A track that will run high-speed trains in excess of 120 mph (193 km/h) is being tested in Illinois between Chicago and St. Louis, Missouri. Here, due to the high speed of the trains, gates that totally prevent road traffic from reaching the tracks are mandatory on all level crossings. Steel mesh nets were tested on some crossings to further prevent collisions, but these were removed because of maintenance issues in 2001. A new device called "Stop Gate" has been installed at four locations, one in Madison, Wisconsin; another in Monroe, Wisconsin and two in Santa Clara, California (on a light rail system). This system resembles a fortified version of a standard crossing gate, with two larger arms blocking the entire width of the roadway and locking into a securing device on the side of the road opposite the gate pivot mechanism. The gate arms are reinforced with high-strength steel cable, which helps the gate absorb the impact of a vehicle attempting to crash through the gate. The manufacturer claims that the Stop Gate can arrest a 2,000 Kg truck within 13 feet (four meters). Already the system has been tested at the Madison crossing, when the system stopped a truck while a Wisconsin and Southern Railroad train was in the crossing. Some level crossings, such as the one in Acton, Massachusetts, are also equipped with sidewalk gates.
Figure 390: A traditional mechanical crossing bell
Page 239 of 259
Figure 391: A level crossing sign on the Romney, Hythe and Dymchurch Railway at St Mary's Bay railway station, UK
Figure 392: A manually operated level crossing in Siliguri, India.
Figure 393: Europe uses a St Andrew's Cross to warn road users
Page 240 of 259
5.9.1.3
Crossbuck
A crossbuck is a sign composed of two slats of wood or metal of equal length, fastened together on a pole in a saltire formation (resembling the letter "x"). Crossbucks are usually used as traffic signs to indicate level railway crossings, sometimes supplemented by electrical warnings of flashing lights, a bell, and/or a metal arm that descends to block the road and prevent traffic from crossing the railroad.
Figure 394: Crossbuck with white background and black lettering (as used in the United States and Australia)
5.9.1.4
International variants
In the United States and Australia, the crossbuck carries the word "RAILROAD" ("RAILWAY" in Australia) on one arm and "CROSSING" on the other, in black text on a white background. Older variants simply used black and white paint, but newer installations use a reflective white material with non-reflective lettering. Some antique U.S. crossbucks were painted in other colour schemes, and used glass "cat's eye" reflectors on the letters to make them stand out. Other countries, such as China, also use this layout, but with appropriately localized terms. In Canada, crossbucks have a red trim and no lettering. These were installed in the 1980s shortly after English-French bilingualism was made official, replacing signs of a style similar to those used in the United States except the word "RAILWAY" was used instead. In parts of Europe, the cross is white on a rectangular red background; in Finland the cross is yellow, trimmed with red. In Taiwan, the cross is white with a red border. A special symbol in the centre indicates an electric railroad crossing to caution road users not to have anything too high that may cause electric hazards.
St. Andrew's Cross–like crossbuck in white on red
5.9.1.5
Crossbuck in yellow trimmed with red as Crossbuck in Taiwan found in Finland Figure 395: International Variants of the Crossbuck
Crossbuck in Taiwan for an electric crossing
Multiple Tracks
Several countries use a sign to indicate that multiple tracks must be crossed at a level crossing. In the United States and Canada, a sign is mounted beneath the crossbuck (above the warning light assembly, if any) with the number of tracks. Many European countries use multiple crossbucks or additional chevrons ("half-crossbucks") below the first one. Taiwan uses half-crossbucks below the first one as well.
Double crossbuck at a level crossing in the Netherlands
"One-and-a-half" crossbucks, as found "One-and-a-half" crossbucks in in Finland Taiwan Figure 396: Multiple tracks at a crossbuck
Page 241 of 259
"One-and-a-half" crossbucks in Taiwan for an electric crossing
6
Rail Gauge
Rail gauge is the distance between the inner sides of the two parallel rails that make up a railway track. The gap is measured at a specific point below the rail head (P-point).
Figure 397: Rail Gauge
Measurement of track gauge is useful in identifying deterioration in the track due to rail side wear or chair movement. The measurement may depend on whether the track is in a loaded (Loaded Track Measurement or Dynamic Measurement: the geometry of the track may be different when loaded or unloaded, i.e. when a train is passing. This may be due to voids beneath sleepers or loose chairs) or unloaded condition. Due to the centrifugal force of traffic in a curve, the side of a rail will become worn down. The measurement of side wear is given as the reduction in width of the rail from the nominal new rail size. This is measured at a specific point below the rail head (P-point). Gauge is often intentionally widened slightly on curved track. Some stretches of track are dual gauge, with three (or sometimes four) parallel rails in place of the usual two, to allow trains of two different gauges to share the same path. The term break-of-gauge refers to the situation at a place where different gauges meet. Today sixty percent of the world’s railways use a gauge of 4 ft 8½ in (1435 mm), which is known as the standard or international gauge. Gauges wider than standard gauge are called broad gauge, those smaller than standard narrow gauge.
Figure 398: Railway gauges around the world
6.1 Standard gauge As railways developed and expanded one of the key issues to be decided was that of the rail gauge (the distance, or width, between the inner sides of the rails) that should be used. The eventual result was the adoption throughout a large part of the world of a standard gauge of 1435 mm (4 ft 8½ in), allowing inter-connectivity and the inter-operability of trains. Currently 60% of the world's railway lines are built to this gauge. It is also named Stephenson gauge after George Stephenson. In England some early lines in colliery areas in the north east of the country were built to a gauge of 4 ft 8 in (1422 mm); in Scotland some early lines were 4 ft 6 in (1372 mm) (Scotch gauge). Soon, in both countries, these lines were widened to standard gauge. Parts of the United States rail system, mainly in the northeast, adopted the same gauge because some early trains were purchased from Britain. However, until well into the second half of the 19th century Britain and the USA had several different track gauges. The American gauges slowly converged as the advantages of equipment interchange became more and more apparent; the destruction of much of the South's broad gauge system in the American Civil War hastened this trend.
Page 242 of 259
6.1.1
Origin
There is a story on the early origins of the standard gauge that rail gauge was derived from the rut ways created by war chariots used in Imperial Rome, which everyone else had to follow to preserve their wagon wheels, and because Julius Caesar set this width under Roman law so that vehicles could traverse Roman villages and towns without getting caught in stone ruts of differing widths. A problem with this story is that the Roman military did not use chariots in battle. However, an equal gauge is probably coincidence. Excavations at the buried cities of Pompeii and Herculaneum revealed ruts averaged 4 ft 9 in (1448 mm) centre to centre, with a gauge of 4 ft 6 in (1372 mm). The designers of both chariots and trams and trains were dealing with a similar issue, namely hauling wheeled vehicles behind draft animals. Ambrussum has some extant Roman chariot tracks. Another example is after Qin Shihuang unified China, he started to make the standard gauge length for the carriage and chariot. A more likely theory as to why the 1,435 mm (4 ft 8½ in) measurement was chosen is that it reflects vehicles with a 1524 mm (5 ft) outside gauge. Italy defined its gauges from the centres of each rail, rather than the inside edges of the rails, giving some unusual measurements. The English railway pioneer George Stephenson spent much of his early engineering career working for the coalmines of County Durham. The Stockton and Darlington Railway (S&DR), the world's first steam-powered railway, was built primarily to transport coal from several mines near Shildon to the port at Stockton-on-Tees. The S&DR's track gauge of 4 ft 8 in (1422 mm) was set to accommodate the existing gauge of hundreds of horse-drawn chaldron wagons that were already in use on the wagon ways in the mines. Stephenson used the same gauge (with an extra half-inch of slack) for the Liverpool and Manchester Railway opened five years later. The success of this led to Stephenson being employed to engineer several other larger railway projects. This influence appears to be the main reason that this particular gauge became the standard, and its usage became more widespread than any other gauge. Subsequently, engineers have shown that a narrow gauge is less than ideal: despite usually offering cheaper construction, a smaller gauge restricts speeds due to reduced load stability. Broader gauges are theoretically more stable at speed and allow larger, wider, heavier loads. According to Isambard Kingdom Brunel's studies the optimum gauge for a rail system (and the one he originally used on his Great Western Railway) is 7 ft 0¼ in (2140 mm). In the United Kingdom, a Royal Commission in 1845 reported in favour of standard gauge on the grounds that its network was eight times larger than that of the rival 7 ft 0¼ in (2140 mm) gauge adopted principally by the Great Western Railway. The subsequent Gauge Act of 1846 ruled that new railways in Great Britain should be built to standard gauge, but allowed the broad gauge companies to continue expanding their networks. After an intervening period of mixed-gauge operation (tracks were laid with three running-rails), the Great Western finally converted its entire network to standard gauge in 1892. A popular legend traces the origin of the 4 ft 8½ in (1435 mm) gauge even further back than the coalfields of northern England, pointing to the evidence of rutted roads marked by chariot wheels dating from the Roman Empire. This legend may have some truth, as there is a historical tendency to place the wheels of horse-drawn vehicles approximately 5 ft (1524 mm) apart, which probably derives simply from the width needed to fit a carthorse in between the shafts.
6.1.2
Ideal gauge
There has been much controversy about what constitutes the "ideal gauge". From a design point of view, a train can travel faster around a given radius of track if the gauge is wider, as the centre of gravity of the train is therefore further displaced from the wheels, which in turn lowers the angle between the wheel's lower contact surface to the centre of gravity, and horizontal. Given that one can tailor either the track radius for train speed, or the train speed for track radius, gauge in some cases may not be as important as interoperability. There are many examples of high speed and high mass applications on narrow gauges throughout the world suggesting that gauge is less important than the original supporters of broad or narrower gauges held it to be:
The heaviest trains in the world run on standard gauge track in Australia, North America and Mauritania. Gauge is not the limiting factor in running heavier trains. The fastest trains in the world run on standard gauge in Japan and Europe at speeds over 300 km/h. Very heavy trains run on the narrow gauge of 3 ft 6 in (1067 mm) in Queensland (Australia) and South Africa, on track as strong as heavy standard gauge track. A narrow gauge does not seem to materially affect the weight of trains that can be run. Fairly fast trains can run on narrow gauge track, as can be seen in Queensland. It is possible to build a light standard gauge line about as cheaply as a narrow gauge line. It is possible to build a narrow gauge line to as heavy-duty a standard as a standard gauge line. Loading gauge, structure gauge, axle load, compatibility of couplings, continuous brakes, electrification system, railway signal systems, radio systems and rules and regulations are also important.
With the benefit of hindsight, little was gained by building railway systems too narrow (down to about 3 ft (900 mm)) or too broad (up to about 7 ft (2100 mm)) gauges, and this was at the cost of limited interoperability. For an example of the difficulties of interoperability see the Ramsey Car Transfer Apparatus and the Variable gauge axles used to transfer cars between different gauges of track. Only in gauges of less than 3 ft (914 mm) can a railway be built significantly more cheaply than is possible with standard gauge, and only then in mountainous terrain, or where a low capacity line is required, or with industrial railways where through running is not required. It can be argued therefore, that the original uniform gauge adopted by Stephenson in 1830 can serve most of the tasks performed by gauges from 3 to 7 ft (900 to 2100 mm), albeit with a mini gauge of about 2 ft (600 mm) for cane tramways, underground mine, mountain, construction, temporary and military railways, plus children's railways.
Page 243 of 259
6.1.3
Piggyback operation
For interoperability, if possible, the mini-gauge trams should be able to piggyback on top of standard gauge flat wagons, to reach workshops and other narrow gauge lines to which they are not otherwise connected. Piggyback operation by the trainload occurred as a temporary measure between Port Augusta and Marree during gauge conversion works in the 1950s, to bypass steep gradients in the Flinders Ranges. Piggyback operation was a permanent feature of the Padarn Railway in North Wales. It is also possible for standard gauge vehicles to operate over narrow gauge tracks using adaptor vehicles; the Rollbocke transporter wagon arrangements in Germany, Austria and the Czech Republic are examples.
6.1.4
Break of gauge
When a railway line of one gauge meets another railway line of a different gauge, there is a break of gauge. A break of gauge adds cost and inconvenience to traffic that must pass from one system to another. An example of this is on the Transmanchurian Railway, where Russia and Mongolia use broad gauge while China uses the standard gauge. At the border, each carriage has to be lifted in turn to have its bogies changed. The whole operation, combined with passport and customs control, can take several hours. This can be avoided however by implementing a system similar to that used in Australia, where lines between states using different gauges are built as dual gauge. Thus the lines have 3 rails, one set of two forming a standard gauge line, with the third rail either inside or outside the standard set forming rails at either narrow or broad gauge. As a result, trains built to either gauge can use the line.
6.2 Broad gauge 6.2.1
Details
In Britain the Great Western Railway designed by Isambard Kingdom Brunel pioneered broad gauge from 1838 with a gauge of 7 ft 0¼ in (2140 mm), and retained this gauge until 1892. While Parliament was initially prepared to authorise lines built to the broad gauge, the Gauge Commission eventually rejected it in favour of all railways being built to Standard Gauge for compatibility. Broad gauge lines were gradually converted to dual gauge or standard gauge from 1864, and finally the last of Brunel's broad gauge was converted in 1892. Many countries have broad gauge railways. Ireland and some parts of Australia have a gauge of 5 ft 3 in (1600 mm) (but Luas, the Dublin light rail system, is built to standard gauge). Russia and the other former Soviet Republics use a 1520 mm (originally 5 ft (1524 mm)) gauge while Finland continues to use the 5 ft (1524 mm)) gauge inherited from Imperial Russia (the two standards are close enough to allow full interoperability between Finland and Russia). In 1839, the Netherlands started its railway system with two broad gauge railways. The chosen gauge was 1945 mm after a visit of engineers in England. This was applied between 1839 and1866 by the Hollandsche IJzeren Spoorweg-Maatschappij (HSM) for their Amsterdam-The HagueRotterdam line and between 1842 and 1855, firstly by the Dutch state, but soon by the Dutch Rhenish Railway Co. (NRS) for their AmsterdamUtrecht-Arnhem line. But the neighbouring countries Prussia and Belgium used already standard gauge so the two companies had to re-gauge their first lines. In 1855, NRS re-gauged its line and shortly after connected to the Prussian railways. The HSM followed in 1866. There are replicas of one broad gauge 2-2-2 locomotive (De Arend) and three carriages in the Dutch Railway Museum in Utrecht. These replicas were built for the 100th anniversary of the Dutch Railways in 1938–39. The Baltic States have received funding from the European Union for rebuilding their railways to the standard gauge. Portugal and the Spanish Renfe system use a gauge of 5 ft 5½ in (1668 mm) called "Ancho Ibérico". In India a gauge of 5 ft 6 in (1676 mm) is widespread. This is also used by the Bay Area Rapid Transit (BART) system of the San Francisco Bay Area. In Toronto, Canada the TTC subways and streetcars use a unique gauge of 4 feet 10 7/8 inches (1495 mm), an "over-gauge" originally intended to allow standard gauge horse-drawn wagons to run inside the rails while the streetcars ran on top of them. Most non-standard broad gauges get in the way of interoperability of railway networks. On the GWR, the 7 ft 0¼ in (2140 mm) gauge was supposed to allow for high speed, but the company had difficulty with locomotive design in the early years (which threw away much of their advantage), and rapid advances in permanent way and suspension technology saw standard gauge speeds approach broad gauge speeds within a decade or two in any case. On the 5 ft 3 in (1600 mm) and 5 ft 6 in (1676 mm) gauges, the extra width allowed for bigger inside cylinders and greater power, a problem solvable by outside cylinders and higher steam pressure on standard gauge. On BART, the wider gauge is supposed to prevent lightweight trains from being blown over by the wind. The British Raj in India adopted 5 ft 6 in (1676 mm) gauge, although some standard gauge railways were built in the initial period. The standard gauge railways were soon converted to broad gauge. Reputedly, broad gauge was thought necessary to keep trains stable in the face of strong monsoon winds. Attempts to economise on the cost of construction led to the adoption of 1 m (3 ft 33⁄8 in) gauge and then 2 ft 6 in (762 mm) and 2 ft (610 mm) narrow gauges for many secondary and feeder lines. However, broad gauge remained the most prevalent gauge across the Indian subcontinent, reaching right across from Iran to Burma and Kashmir to Tamil Nadu. After Independence, the Indian Railways adopted 5 ft 6 in (1676 mm) as the standard Indian Gauge, and began Project Unigauge to convert metre gauge and narrow gauge to broad gauge. Even the newest projects in India such as the Konkan Railway and Delhi Metro use broad gauge. A move to use standard gauge for the Delhi Metro was amended to broad gauge for compatibility with the Indian rail network.
Page 244 of 259
6.2.2
Broader gauges
Some applications for railways require broader gauges, including Telescopes, Rocket launchers - USSR used double track 5' 0" gauge; US prefers trackless Caterpillar trucks, Dockside cranes for unloading cargo from ships and for constructing ships, Ship railways. These applications might use double track of the country's usual gauge to provide the necessary stability and axle load. These applications may also use much heavier than normal rails, the heaviest for trains being about 70kg/m. Britain The standard gauge of 4 ft 8½ in (1435 mm) was chosen for the first main-line railway the Liverpool and Manchester Railway (L&MR), by the British engineer George Stephenson, because it was the de facto standard for the colliery railways where Stephenson had worked. Whatever the origin of the gauge it seemed to be a satisfactory choice: not too narrow and not too wide. Brunel on the Great Western Railway chose the broader gauge of 7 ft 0¼ in (2140 mm) partly because it offered greater stability and capacity at high speed, but also because the Stephenson gauge was not scientifically selected. The Eastern Counties Railway chose five-foot gauge, but soon realised that the lack of compatibility was a mistake and changed to Stephenson’s gauge. In 1845 a British Royal Commission recommended adoption of 4 ft 8½ in (1435 mm) as standard gauge, and in the following year Parliament passed the Gauge Act, which required that new railways use standard gauge. Except for the Great Western Railway’s broad gauge, few main-line British railways used a different gauge, and the last Great Western line was finally converted to standard gauge in 1892. Russia Although it is a popular myth that Russian gauge was selected wider to prevent railroad invasion, this is not true. Russian gauge of 5 ft was approved as the new standard on September 12, 1842. Mel’nikov who probably used these arguments chiefly did the selection process:
Easier construction of locomotives Better stability Wide gauge was seen as a new standard that was emerging in the United States Since the gauge was wider than standard track it was easier to use horse carriages for railroad construction and maintenance.
George Washington Whistler was invited as a foreign expert to assist in railroad construction. He was a proponent of a wider gauge and his efforts helped in lobbying the new standard. It is quite likely that an "invasion" argument (alleging that it is easier to adapt trains to narrow gauge than to wide gauge) was used in lobbying the project since military was closely supervising the construction; however, it is highly unlikely that Mel’nikov made such an argument during the actual selection process. Nazi Germany suffered such problems with their supply lines during World War II because of the break-of-gauge. Although broad gauge was and is quite rare on lighter railways and street tramways, many tramways in ex-USSR were and are also built to broad gauge (according to terminology in use in these countries, gauges narrower than 1520 mm are considered to be narrow). The former Soviet Union is today the largest operator of first generation tramways in the world, and has been for many years. The modern world's largest tramway network, in Saint Petersburg, Russia, is entirely broad gauge, with some of the world's widest trams, and indeed the widest in Europe (European trams are generally narrower than European buses and trains and also tramcars elsewhere such as in America and Australia). In the 19th century, Russia chose a broader gauge. It is widely believed that the choice was made for military reasons, to prevent potential invaders from using the Russian rail system. Others point out that no clear standard had emerged by 1842. Engineer Pavel Melnikov hired George Washington Whistler, a prominent American railroad engineer (and father of the artist James McNeill Whistler), to be a consultant on the building of Russia’s first major railroad, the Moscow – St Petersburg line. The selection of 1.5 m gauge was recommended by German and Austrian engineers but not adopted: it was not the same as the 5 ft (1524 mm) gauge in common use in the southern United States at the time. Now Russia and most of the former USSR, including the Baltic States, Ukraine, Belarus, the Caucasian and Central Asian republics, and Mongolia, have the Russian gauge of 1520 mm, 4 mm narrower than 5 ft (1524 mm), though rolling stock of both gauges is interchangeable in practice. Finland Finland, a Grand Duchy under Russia in the 19th century, uses 5 ft (1524 mm) gauge. Upon gaining independence in 1917, much thought was given to converting to standard gauge, but nothing came of it. Iberian Peninsula The main railway networks of Spain and Portugal were constructed to gauges of six Castilian feet (1672 mm) and five Portuguese feet (1664 mm). The two gauges were sufficiently close to allow interoperation of trains, and in recent years they have both been adjusted to a common “Iberian gauge of 1668 mm. Although it has been said that the main reason for the adoption of this non-standard gauge was to obstruct any invasion attempts coming from France, it was in fact a technical decision, to allow for the running of larger, more powerful locomotives in a mountainous country. Since the beginning of the 1990s new high-speed passenger lines in Spain have been built to the international standard gauge of 4 ft 8½ in (1435 mm), since it is intended that these lines will cross the French border and link to the European high-speed network. Although the 22 km from Tardienta to Huesca (part of a branch from the Madrid to Barcelona high-speed line) has been reconstructed as mixed Iberic and standard gauge, in general the interface between the two gauges in Spain is dealt with by means of gauge-changing installations, which can adjust the gauge of appropriately designed rolling stock on the move.
Page 245 of 259
United States Originally, a variety of gauges was used in the United States and Canada. Some railways, primarily in the northeast, used standard gauge; others used gauges ranging from 4 ft (1219 mm) to 6 ft (1829 mm). Given the nation’s recent independence from the United Kingdom, arguments based on British standards had little weight. Problems began as soon as lines began to meet and in much of the northeastern United States standard gauge was adopted. Most Southern states used 5 ft (1524 mm) gauge. Following the American Civil War, trade between the South and North grew and the break of gauge became a major economic nuisance. Competitive pressures had forced all the Canadian railways to convert to standard gauge by 1880, and Illinois Central converted its south line to New Orleans to standard gauge in 1881, putting pressure on the southern railways. After considerable debate and planning, most of the southern rail network was converted from 5 ft (1524 mm) gauge to 4 ft 9 in (1448 mm) gauge, then the standard of the Pennsylvania Railroad, over two remarkable days beginning on May 31, 1886. Over a period of 36 hours, tens of thousands of workers pulled the spikes from the west rail of all the broad gauge lines in the South, moved them 3 inches east and spiked them back in place. The new gauge was close enough that standard gauge equipment could run on it without problem. As of June 1886, all major railroads in North America were using basically the same gauge. The final conversion to standard gauge took place gradually as track was maintained. In modern uses isolated occurrences of non-standard gauges can be found, such as the 5ft 21⁄4 in (1581 mm) and 5 ft 21⁄2 in (1588 mm) gauge tracks of the Philadelphia streetcars, the Philadelphia subway cars and the New Orleans streetcars. The Bay Area Rapid Transit system in the San Francisco Bay Area, choose 5 ft 6 in (1676 mm) gauge. Commonwealth of Nations (former British Empire): Australia In the 19th century, Australia's three mainland states adopted standard gauge, but due to political differences a break of gauge 30 years in the future was created. After instigating a change to 5 ft 3 inch (1600 mm) agreed to by all, New South Wales reverted to standard gauge while Victoria and South Australia stayed with broad gauge. Three different gauges are currently in wide use in Australia, and there is little prospect of full standardisation, though the main interstate routes are now standard gauge. Canada The first railway in British North America, the Champlain and St. Lawrence Railroad, was built in the 1830s to 5’-6” (1676 mm) gauge, setting the standard for Britain’s colonies for several decades. Well-known colonial systems such as the Grand Trunk Railway and Great Western Railway, along with the European and North American Railway and Nova Scotia Railway later expanded the use of broad gauge. In 1851 the 5’-6” (1676 mm) broad gauge was universally adopted as the standard gauge for the Province of Canada. The broad gauge was used until the early 1870s, after which there was a gradual change to standard gauge over several years. The rise in standardization with the U.S. came about because of increasing trade across the border after the American Civil War. Some railways installed dual gauge track, which was expensive, and others used variable gauge wheels, which proved unreliable. The Grand Trunk system started converting its borderlines in 1872 and finished converting its lines east of Montreal in 1874. The Canadian government-owned Inter-colonial Railway converted from broad to standard gauge in 1875 while still under construction. After the 1870s, the Canadian Pacific Railway and most major new lines were built to the standard gauge, including railways built through the Canadian Rocky Mountains to the Pacific coast. These included the Grand Trunk Pacific Railway, the Canadian Northern Railway and the Pacific Great Eastern Railway that were eventually acquired by Canadian National Railway, the largest railway in Canada. All remaining Canadian freight railways use standard gauge. In Toronto the Toronto Transit Commission subways and streetcars use 1495 mm (4 ft -10_ in) gauge, making their equipment incompatible with all other city transit systems. This apparently arose because in the early days the streetcar tracks were broadened slightly so that horse-drawn wagons could ride on the inside flanges of the rails rather than on the sloppy streets of Muddy York, as it was known. Ireland The track gauge adopted by the mainline railways in Ireland is 5 ft 3 in (1600 mm). This unusual gauge is otherwise found only in the Australian states of Victoria, southern New South Wales (as part of the Victorian rail network) and South Australia (where it was introduced by the Irish railway engineer F. W. Shields), and Brazil. The first three railways all had different gauges: the Dublin and Kingstown Railway, 4 ft 8½ in (1435 mm); the Ulster Railway, 6 ft 2 in (1880 mm); and the Dublin and Drogheda Railway, 5 ft 2 in (1575 mm). The Board of Trade, recognising the chaos that would ensue, asked one of their officers to advise. After consulting widely he eliminated both the widest and narrowest gauges (Brunel's 7 ft 0¼ in (2140 mm) and Stephenson's 4 ft 8½ in (1435 mm)), leaving gauges between 5 ft 0 in and 5 ft 6 in. By splitting the difference, a compromise Irish gauge of 5 ft 3 in was adopted. South Asia Bangladesh, India, Pakistan and Sri Lanka inherited a diversity of rail gauges, of which 1676 mm was predominant. Indian Railways has adopted Project unigauge, which seeks to systematically convert most of its narrower gauge railways to the 1676 mm. The People's Republic of China Most of the railway network of the People's Republic of China is standard gauge.
Page 246 of 259
Afghanistan Afghanistan is in an interesting position, because it is at the crossroads of Asia and is virtually without railways. Should it decide to build any, the choice of gauge will be complicated by its being surrounded by three different gauges. Iran to the west uses standard gauge, as does China to the east; to the south, Pakistan uses 1676 mm gauge, while to the north, the central Asian republics of Turkmenistan, Uzbekistan, and Tajikistan use 1520 mm. Hong Kong In Hong Kong, the Mass Transit Railway uses 1432 mm gauge, 3 mm narrower than standard gauge. A new railway line is across the Hong KongZhuhai-Macau Bridge, an extension to the 1432 mm gauge Tung Chung Line. This 3 mm difference should cause no more problems than the 4 mm difference caused between Russia and Finland nor that the former 8 mm difference did between Spain and Portugal. Caribbean: Cuba Mostly standard gauge Jamaica Standard gauge South America Argentina and Chile use 1676 mm gauge. Brazil uses 1600 mm (known as “broad gauge”, most common for passenger services and few corridors in the Southeast) and 1000 mm (known as “narrow gauge” or “metric gauge”, most common for cargo services). Exceptions are the Estrada de Ferro do Amapá North of the River Amazon, which has 1440 mm gauge and the new Line 5 of São Paulo Metro, which uses standard gauge. Argentina, Paraguay, Uruguay and Peru use standard gauge. In the past a few lines in Northern Chile had also 1435 mm gauge, as the only international railway from Arica (Chile) to Tacna (Peru) a bit more than 60 km still use 1435 mm. El Cerrejón Coal Railway and Venezuelan Railways are also 1435 mm.
6.3 Scotch gauge Scotch gauge was the name given to a 4 ft 6 in (1372 mm) rail gauge, the distance between the inner sides of the rails adopted by early 19th century railways mainly in the Lanarkshire area of Scotland. It differed from the gauge of 4 ft 8 in (1422 mm) that was used on some early lines in England and from Standard gauge. It became obsolete in the early 1840s when Standard gauge lines began to be constructed in Scotland.
6.3.1
End of Scotch gauge
The Glasgow, Paisley, Kilmarnock and Ayr Railway and the Glasgow, Paisley and Greenock Railway, which both obtained Parliamentary Approval on 15 July 1837 and were later to become part of the Glasgow and South Western Railway and the Caledonian Railway, respectively, were built to Standard Gauge from the start. The Standard gauge of 4 ft 8½ in (1435 mm), also known as the Stephenson gauge after George Stephenson, was adopted in Great Britain after 1846.
6.4 Narrow gauge A narrow gauge railway (or narrow gauge railroad) is a railway that has a track gauge narrower than the 1,435 mm (4 ft 8½ in) of standard gauge railways. Most existing narrow gauge railways have gauges of 3 ft 6 in (1067 mm) or less. In many areas a much narrower gauge was chosen. While narrow gauge generally cannot handle as much tonnage, it is less costly to construct, particularly in mountainous regions. Plantations such as for sugar cane and bananas are appropriately served by narrow gauges such as 2 ft (610 mm), as there is little through traffic to any other systems.
Figure 399: Comparison of standard gauge (blue) and one common narrow gauge (red) width
Page 247 of 259
6.4.1
Overview
Since narrow gauge railways can accommodate smaller radius curves, they can be substantially cheaper to build, equip, and operate than standard gauge railways, particularly in mountainous terrain. The lower costs of narrow gauge railways mean they are often built to serve industries and communities where the traffic potential would not justify the costs of building a standard gauge line. Narrow gauge railways also have specialized use in mines and other environments where their smaller loading gauge is an advantage. On the other hand, standard gauge railways generally have a greater haulage capacity and allow greater speeds than narrow gauge systems. Historically, many narrow gauge railways were built as part of specific industrial enterprises and were primarily industrial railways rather than general carriers. Some common uses for these industrial narrow gauge railways were mining, logging, construction, tunnelling, quarrying, and the conveying of agricultural products. Extensive narrow gauge networks were constructed in many parts of the world for these purposes. Significant sugarcane railways still operate in Cuba, Fiji, Java, the Philippines and in Queensland in Australia. Narrow gauge railway equipment remains in common use for the construction of tunnels. The other significant reason for narrow gauge railways to be constructed was to take advantage of reduced construction costs in mountainous or difficult terrain, hence the national railway systems of countries such as Indonesia, Japan and New Zealand are primarily or solely narrow gauge. Non-industrial narrow gauge mountain railways are or were common in the Rocky Mountains of the USA and the Pacific Cordillera of Canada, in Mexico, Switzerland, the former Yugoslavia, Greece, India, and Costa Rica. Another country with a notable national railway built to narrow gauge is South Africa where the "Cape gauge" of 3 ft 6 in (1067 mm) is the most common gauge.
6.4.2
History of narrow gauge railways
The earliest recorded railway is shown in the De re metallica of 1556, which shows a mine in the Czech Republic with a railway of approximately 2 ft (610 mm) gauge. During the 16th century railways were mainly restricted to hand-pushed narrow gauge lines in mines throughout Europe. During the 17th century mine railways were extended to provide transportation above ground. These lines were industrial, connecting mines with nearby transportation points, usually canals or other waterways. These railways were usually built to the same narrow gauge as the mine railways they developed from.
6.4.3
Advantages of narrow gauge
Narrow gauge railways cost less to build because they are lighter in construction, using smaller cars and locomotives as well as smaller bridges, smaller tunnels and tighter curves. Narrow gauge is thus often used in mountainous terrain, where the savings in heavy civil engineering work can be substantial. It is also used in very sparsely populated areas where the potential demand is too low for the building of broader gauge railways to be economically viable. This is the case in most of Australia and Southern Africa, where extremely old soils can support only population densities too low for standard gauge to be viable. There are many narrow gauge street tramways, particularly in Europe where metre-gauge tramways are common. Narrow gauge allows tighter turning in restricted city streets. The tighter turning circle also allows balloon loops at the end of routes, which in turn allows the use of unidirectional trams with a driver's cab at one end only, and doors on one side, and thus more space for passengers. Extensive narrow gauge railway systems served the front-line trenches of both sides in World War I. After the end of the war the surplus equipment from these railways created a small boom in the building of narrow gauge railways in Europe. For temporary railroads that will be removed after a short-term need, such as for construction, the logging industry and the mining industry, a narrow gauge railroad is substantially cheaper and easier to install and remove. However, this use of railroads is almost extinct thanks to the capabilities of modern trucks. In many countries narrow gauge railroads were built as "feeder" or "branch" lines to feed traffic to more important standard gauge railroads, due to their lower construction costs. The choice was often not between a narrow gauge railroad and a standard gauge one, but between a narrow gauge railroad and none at all.
6.4.4
Disadvantages of narrow gauge
Narrow gauge railroads cannot interchange equipment like freight and passenger cars freely with the standard gauge railroads they link with, unless they use variable gauge axles. That means that narrow gauge lines have a built-in cost of transhipping people and freight to the mainline railway system. The cost of transhipment can be a substantial drain on the finances of a railroad because it involves expensive and time-consuming manual labour or substantial capital expenditure. Some bulk commodities, such as coal, ore and gravel, can be mechanically transhipped, but this still incurs time penalties and these mechanical devices are often complex to maintain. Solutions to the problem of transhipment include variable gauge axles and bogie exchange between cars. Another solution to this problem is the rollblock system. Although successfully deployed in countries such as Germany, this technique came too late for the majority of narrow gauge lines. The problem of interchangeability is less serious for countries that have a large system of narrow gauge lines, such as northern Spain, and does not exist in those countries in which the narrow gauge is the "standard", such as New Zealand, South Africa and the Australian island state of Tasmania.
Page 248 of 259
The problem of interchangeability is more serious in North America because a continent-wide system of freight car interchange developed. All the standard gauge railways in North America use the same standard couplings and air brakes, which means that freight cars can be freely interchanged between railways from Northern Canada to Southern Mexico. Railways that need more freight cars can simply borrow them from other railways during peak periods, while the railways that own the cars receive payments for them at rates set by common agreement. Peak demand, particularly for grain shipment, occurs in different parts of North America at different times, so freight cars are shuffled back and forth across the continent to wherever they are needed. Motive power can also be interchanged, which sometimes results in Mexican locomotives pulling Canadian freight cars and vice versa. Narrow gauge railways could not participate in this system, which meant that they usually had to own several times as much rolling stock as standard gauge railways, and they did not receive any cash flow for surplus equipment during periods of low demand. Since most narrow gauge railways were short of money to begin with, this eventually resulted in nearly all North American narrow gauge railways either going bankrupt or being bought up by profitable standard gauge railways. Narrow gauge lines were very vulnerable to competition from trucks. The railroads' advantage has always been economy of scale and distance, and the transhipment requirement removed that. Trucks have no such transhipment problem and are more flexible in operation. Another problem with narrow gauge railroads is that they lacked room to grow - their cheap construction was bought at the price of being engineered only for their initial traffic demands. While a standard or broad gauge railroad could more easily be upgraded to handle heavier, faster traffic, many narrow gauge railroads were impractical to improve. Speeds and loads hauled could not increase, so traffic density was significantly limited. Narrow gauge railroads can be built to handle increased speed and loading, but at the price of removing most of the narrow gauge's cost advantage over standard or broad gauge. Because of the reduced stability of narrower gauge, narrow gauge trains are not able to run at nearly the same high speeds as those networks with broader gauges unless the tracks are aligned with greater precision. However in Japan and Queensland, recent track improvements have allowed trains on 1067 mm gauge tracks to run at 160 km/h (100 mph) and higher. Queensland Rail's tilt train is presently the fastest train in Australia, despite the gauge it runs on. Standard gauge or broad gauge trains can run at up to 320 km/h (200 mph); this is most evident in the case of the Japanese Shinkansen, a network of standard gauge lines built solely for high speed rail in a country where narrow gauge is the predominant standard.
6.4.5
Exceptions to the rule
The heavy duty 3 ft 6 in (1067 mm) narrow gauge railways in South Africa and Queensland, Australia, show that if the track is built to a heavy-duty standard, a performance almost as good as a standard gauge line is possible. 200-car trains operate on the Sishen-Saldanha railroad in South Africa, and high-speed tilt-trains in Queensland. Another example of a heavy-duty narrow gauge line is EFVM in Brazil. Metre gauge, it has over-100-pound rail and a loading gauge almost as large as US non-excess-height lines. It sees 4000 hp locomotives and 200+ car trains. Narrow gauge lines are more limited in the capacity and stability of their trains. Similarly, standard and broad gauge lines can be built cheaply to light railway standards, with trains operating at lower speeds and with lower capacities, and these lines were often built instead of narrow gauge railways.
6.4.6
Gauges used
There are many narrow gauges in use between 15 in (381 mm) gauge and 4 ft 8 in (1422 mm) gauge. These fall into three broad categories:
6.4.6.1
Medium gauge railways
The wider narrow gauges are the more common; in those parts of the world where the railroads were built to British standards, this meant most commonly a gauge of 3 ft 6 in (1067 mm), while those built to American standards were normally 3 ft (914 mm). Railways built to European metric standards were most commonly of 1 m (3 ft 33⁄8 in) and 900 mm (2 ft 111⁄2 in) gauge. These larger narrow gauges are capable of hauling most traffic with little difficulty and are thus suitable for large-scale "common carrier" applications, although their ultimate speed and load limits are lower than for standard gauge. Railways built on gauges between 3 ft (914 mm) and 4 ft 8 in (1422 mm) are sometimes referred to as "medium-gauge" railways.
6.4.6.2
Two-foot gauge railways
The next natural "grouping" of narrow gauge railroads covers the spread from just below 2 ft (610 mm) to just below 3 ft (914 mm), although the majority are between 2 ft (610 mm) and 760 mm (2 ft 59⁄10 in). These lightweight lines can be built at a substantial cost saving over medium or standard gauge railways, but are very restricted in their carrying capacity. The majority of these were built in mountainous areas and most were to carry mineral traffic from mines to ports or standard gauge railroads. Many were industrial lines rather than common carriers, though there were exceptions such as the extensive 760 mm (2 ft 59⁄10 in) lines built in the former Austro-Hungarian Empire, and the "Maine two footer" lines in New England. The most common metric gauges in this group are 760 mm (2 ft 59⁄10 in) and 750 mm (2 ft 51⁄2 in).
6.4.6.3
Minimum gauge railways
Gauges below 600 mm were rare, but did exist. In Britain, Sir Arthur Heywood developed 15 in (381 mm) gauge estate railways, while in France Decauville produced a range of industrial railways running on 400 mm (153⁄4 in) and 500 mm (1 ft 73⁄4 in) tracks, most commonly in such restricted environments such as underground mine railways. A number of 18 in (457 mm) gauge railways were built in Britain to serve ammunition depots and other military facilities, particularly during the First World War. Narrow gauge railways under 1 ft 103⁄4 in (578 mm) gauge are known as minimum gauge railways.
Page 249 of 259
Asia
Bangladesh, India, Pakistan and Sri Lanka inherited a diversity of rail gauges, some of which was 1000 mm. Indian Railways have adopted Project unigauge, which seeks to systematically convert most of its narrower gauge railways to the 1676 mm. Some of the railway network of the People's Republic of China is 1 m (3 ft 33⁄8 in) gauge. Railways of Southeast Asia, e.g. Vietnam, Cambodia, Laos, Thailand, Myanmar and Malaysia are predominantly 1 m (3 ft 33⁄8 in) gauge. The proposed ASEAN Railway would be a standard gauge or dual-gauge, using both metre and standard gauge regional railway networks, linking Singapore at the southern tip of the Malay Peninsula, through the Association of Southeast Asian Nations region, Malaysia, Thailand, Laos and Vietnam to the standard-gauge railway network of the People's Republic of China. Indonesia's railways are predominantly 3 ft 6 in (1067 mm). Japan
Except for the high-speed Shinkansen lines, all of Japan Railway group's network is narrow gauge, built to a gauge of 3 ft 6 in (1067 mm). Taiwan
Taiwan started to build up its railway during the Qing dynasty using 3 ft 6 in (1067 mm) gauge. The Japanese colonial government, which ruled from 1895 to 1945, continued using 3 ft 6 in (1067 mm). The system is under Taiwan Railway Administration, now. The new Taipei Rapid Transit System and the metro system under construction in Kaohsiung are standard gauge. The Taiwan High Speed Rail (HSR) that started operation in January 2007 also uses standard gauge. An isolated 2 ft (610 mm) gauge line on the east coast was regauged to 3 ft 6 in (1067 mm) when the line was interconnected. The Alishan forest railway is narrow gauge 2 ft 6 in (762 mm). Africa
The railways of South Africa and many other African countries, including Angola, Botswana, Congo, Ghana, Mozambique, Namibia, Nigeria, Zambia and Zimbabwe, use 3 ft 6 in (1067 mm) gauge, sometimes referred to as Cape gauge. Kenya, Tanzania, Uganda and others have 1 m (3 ft 33⁄8 in) gauge lines. Britain Britain has a large number of narrow gauge lines (e.g. as shown on 1904 Railway Clearing House Railway Atlas), such as the
Southwold Railway - 3 ft (914 mm), Ffestiniog Railway - 1 ft 111⁄2 in (597 mm), Croesor Tramway - 2 ft (610 mm), Welsh Highland Railway - 1 ft 111⁄2 in (597 mm), Talyllyn Railway - 2 ft 3 in (686 mm), Corris Railway - 2 ft 3 in (686 mm), Welshpool & Llanfair Railway - 2 ft 6 in (762 mm), Vale of Rheidol Railway - 1 ft 111⁄2 in (597 mm), Lynton and Barnstaple Railway - 1 ft 111⁄2 in (597 mm), East Cornwall Mineral Railway - 3 ft 6 in (1067 mm) (which was later converted to standard gauge) and Pentewan Railway - 2 ft 6 in (762 mm) (Former) British Empire and Commonwealth: Australia
Queensland, Tasmania, Western Australia and parts of South Australia adopted 3 ft 6 in (1067 mm) gauge to cover greater distances at lower costs. Most industrial railways are built to 2ft gauge. Three different rail gauges are currently in wide use in Australia, and there is little prospect of full standardisation. Canada
The Prince Edward Island Railway used 3ft 6in (1067mm) Cape gauge from its opening in 1874 until it was merged into the Canadian National Railways in 1918, the same time as a new ferry permitted interchange with North America's rail network. From 1918-1930 there was a mix of standard, dual and narrow gauge in the province until CNR's standardization was completed; standard gauge being maintained until abandonment in 1989. The Newfoundland Railway was constructed to Cape gauge as well, beginning in the 1880s, and this gauge was maintained under CNR ownership post-1949 until abandonment in 1988, except for some dual Cape/standard gauge track used at the ferry terminal to North America's rail network; standard gauge rolling stock was hauled in Newfoundland by changing out standard gauge wheelsets for Cape gauge wheelsets.
Page 250 of 259
New Brunswick Railway used Cape gauge until the 1880s when it was acquired by Canadian Pacific Railway after which standard gauge prevailed. A number of 3ft 0in (914 mm) narrow gauge mining and logging railways were built in the mountains and islands of British Columbia including the Kaslo & Slocan Railway in the late 19th century but have since been converted to standard gauge or abandoned. The 3ft 0in (914 mm) White Pass and Yukon Railroad, which was completed in 1900 at the end of the Klondike gold rush is Canada's last remaining narrow gauge carrier. It no longer carries freight, but is the busiest tourist railroad in North America. Its tracks connect to no other railroad but do connect to the cruise ship docks at Skagway, Alaska, which provide it with most of its passengers. New Zealand
New Zealand adopted narrow gauge 3 ft 6 in (1067 mm) due to the need of cross-mountainous terrain in the country's interior. This terrain has necessitated a number of complicated engineering feats, notably the Raurimu Spiral. There are 1787 bridges and 150 tunnels in less than 4,000 km of track, around 500 km of which is electrified. Caribbean: Haiti Haiti has had two different gauges on its railroads. 130 km of rural line between Port-au-Prince, Saint-Marc, and Verrettes (1905–about 1960s) used 3 ft (914 mm) gauge. Tramlines in Port-au-Prince (1878–1888 and 1896–1932), which was the first known track in Haiti, and a total of 80 km of rural line west to Léogâne and east to Manneville (1896–1950s(?)) used 2 ft 6 in (762 mm) gauge. Totalling over 100 km of track, the plantation railroads in the north and north-east most likely used 2 ft 6 in (762 mm). There were at least four separate isolated lines. The story of the demise of one Haitian railroad is that it was sold and physically picked up, put on ships and sent off to Asia during the Papa Doc period (approx 1957–1971). Others may have been used on the plantation tracks in the north and north-east of Haiti. The CIA fact book suggests that in the 1990s there were only 40 km of abandoned track left(!) South America Argentina, Bolivia, Brazil and Chile have 1 m (3 ft 33⁄8 in) gauge lines. Colombia and Peru have 914 mm gauge lines.
6.5 Dual gauge Dual-gauge or mixed-gauge railway is a special configuration of railway track, allowing trains of different gauges to use the same track. Generally dual-gauge railway consists of three rails, rather than the standard two rails. The two outer rails give the wider gauge, while one of the outer rails and the inner rail give a narrower gauge. Thus one of the three rails is common to all traffic. (This configuration is not to be confused with the electric third-rail.) Dual gauge allows trains of different gauges to share the same track. This can save considerable expense compared to using separate tracks for each gauge, but introduces complexities in track maintenance and signalling, as well as requiring speed restrictions for some trains. If the difference between the two gauges is large enough, for example between 4 ft 8½ in (1435 mm) and 3 ft 6 in (1067 mm), three-rail dual-gauge is possible, but if the difference is not large enough, for example between 3 ft 6 in (1067 mm) and 1 m (3 ft 33⁄8 in), four-rail dual-gauge is used. Dual-gauge rail lines are used in the railway networks of Switzerland, Australia, Argentina, Brazil, North Korea, Tunisia and Vietnam. Africa is particularly affected by gauge problems, where railways of different gauges in adjacent countries meet. Gauge rationalisation in Africa is facilitated since four-rail dual gauge of 1 m (3 ft 33⁄8 in) and 3 ft 6 in (1067 mm) contains a hidden gauge, which can be made to be standard gauge 4 ft 8½ in (1435 mm) . The four-rail system reuses and doubles the effective strength of the old light rails, which might otherwise have only a low value reuse as fence posts.
6.5.1
Configuration
For dual-gauge track to be achievable using three rails, the difference between the gauges needs to be at least as wide as the foot of the rail, otherwise there is no room for the rail fastening hardware (spikes, clips, and the like). Thus standard gauge (1,435 mm (4 ft 8½ in)) and 5 ft 6 in (1676 mm) can be dual gauged without problem, while 4 ft 8½ in (1435 mm) and 5 ft 3 in (1600 mm) (Victorian broad gauge) can also be dual-gauged, albeit with lighter narrow footed rails, as shown in Victoria, Australia (where the majority of the railways use the 1600 mm gauge). On the other hand, 1 m (3 ft 33⁄8 in) and 3 ft 6 in (1067 mm) as found in Africa, or 1 m (3 ft 33⁄8 in) and 3 ft (914 mm), as found in South America, are too close to be combined into three-rail dual gauge. If three-rail dual gauge is impossible, four-rail dual gauge may be possible.
6.5.2
Gauge Conversion
The complications and difficulties outlined show how important it is to ensure that railway gauges are standardised in the first place, if at all possible. If a railway operator seeks to convert from one gauge to another, then it helps if a dual-gauge intermediate step can be done (as done in the past). If the gauge is to be reduced, then the sleepers can continue to protrude from the side of the rails. If the gauge is to be increased, then the sleepers used for narrow gauge may be too short, and some at least of these 'short' sleepers will have to be replaced with longer ones. Alternatively the rails may be too light for the loads imposed by broader-gauge railcars. Such potential problems can rule out dual-gauge as a feasible option. Another issue is affixing the rails to the sleepers (spikes, nails or bolts are used). If existing sleepers are wooden, extra holes can be drilled without problems. If the existing sleepers are concrete, then extra holes are impossible and the whole sleeper has to be replaced, unless extra boltholes are already allowed for.
Page 251 of 259
During the conversion of the Melbourne to Adelaide line in Australia from 5 ft 3 in (1600 mm) to 4 ft 8½ in (1435 mm), dual gauge with heavy rails was not possible as the rail footings were too wide. A special gauge-convertible sleeper with a reversible chair for the Pandrol clip allowed a twoweek conversion process. In the Adelaide metropolitan area, broad-gauge timber sleepers are being replaced with gauge-convertible concrete sleepers, in case of future gauge conversion. During WWI and WWII, gauge conversion occurred backwards and forwards between Europe and Russia as the fronts and national borders chopped and changed. The dual-gauge lines in Java were regauged to Cape gauge (4 ft 8½ in (1435 mm) to 3 ft 6 in (1067 mm)) during the Japanese administration in 19421943. Actual regauging only occurred on the relatively short Brumbung-Kedungjati-Gundih main line and the Kedungjati-Ambarawa branch line, as the rest of the line was already dual-gauge (some only recently dual-gauged).
6.5.3
Cost of an example
In 2005, Pakistan Railways started work on the conversion of the 128km Mirpurkhas to Khokhrapar line from 1 m (3 ft 33⁄8 in) to 5 ft 6 in (1676 mm) gauge. The cost was set at Rs 1,800,000,000 (US$30,000,000), or about US$ 250,000 per km.
6.5.4
Examples In the Czech Republic, there is dual gauge (1435 mm and 760 mm) track near Jindřichův Hradec. Interestingly, the two gauges are used by different railway companies. In Britain, the Great Western Railway was initially broad gauge. After the "gauge war", it was decided to regauge the GWR. As the broad gauge was sufficiently dissimilar from standard gauge and used wooden sleepers, dual gauge was easily introduced for running new standard-gauge traffic. The Metropolitan Railway, part of the London Underground system, also started out as dual-gauge; however, its current third and fourth rails are for electricity supply, not dual gauge. In Ireland, dual-gauge track was not used in regauging the Ulster Railway (UR). When it regauged its double-track route from 1880 mm (6 ft 2 in) to the new standard of 5 ft 3 in (1600 mm) it performed the task in two stages. The Dublin & Drogheda Railway (D&DR) meanwhile was regauging from 1575 mm (5 ft 2 in), too similar to the new gauge to allow dual gauge. Dual gauge was used in Derry, by the Port Authority, in an on-street network to transfer goods, on either gauge, between the city's four stations (two 3 ft (914 mm) narrow gauge, two 5 ft 3 in broad gauge). In Western Australia, there is a double-track dual-gauge (3 ft 6 in (1067 mm) & 4 ft 8½ in (1435 mm)) main line from East Perth to Northam, about 120 km. Dual-gauge track is also used from the triangle at Woodbridge to Cockburn Junction, then to Kwinana on one branch, and North Fremantle on the other. In Brisbane, Queensland, shorter stretches of dual-gauge track (3 ft 6 in (1067 mm) & 4 ft 8½ in (1435 mm)) exist between the rail freight yards at Acacia Ridge and the Port of Brisbane for freight trains. A dual-gauge line branches off at Park Road Station to run alongside electric suburban narrow gauge CityTrain services over the Merivale Bridge into Platform 1 at Roma Street Station. This is used by standard-gauge interstate CountryLink XPT services to Sydney. In Belgium, some sections of tram track in Brussels combined metre gauge for the interurban trams with standard gauge for the urban trams. Since the closure of the former, these have been replaced with standard gauge track. In Stuttgart, Germany, the tram lines were 1000 mm gauge. In the 1970s it was decided to convert the streetcar system to a modern Stadtbahn and regauge it to standard gauge to increase capacity. Inner-city tunnels replacing street-level sections in busy streets were built with a cross-section suitable for standard-gauge cars. After the conversion started in 1981 with the commissioning of the first three class DT-8 Stadtbahn cars, the tunnels and all other sections used by multiple lines were fitted with 1435 mm / 1000 mm dual-gauge track, to allow both old-style streetcars and new Stadtbahn cars to share those sections while lines were converted one by one over the next decades. In 2006, conversion of line 15 (the last line to be converted) was under way and expected to be complete around 2008, although some sections will retain their dual-gauge track indefinitely as a courtesy to the streetcar museum of Stuttgart, which will operate old 1000 mm gauge streetcars on weekends and special occasions. In Switzerland dual gauge (standard and meter) is used in the stations at both ends of the Brünigbahn (Lucerne and Interlaken), as well as on the RhB between Chur and Domat Ems among other places. In Japan, dual gauge is used when the Shinkansen system, which is standard gauge, joins the narrow-gauge (1067 mm) system, which is the national standard. For example, part of the Ōu line became part of the Akita Shinkansen and was upgraded to dual gauge. In Dutch East Indies (later Indonesia), dual-gauge track was installed in 1899 between Yogyakarta and Solo. The track was owned by the Nederlandsch-Indische Spoorweg Maatschappij, a private company, which built the 4 ft 8½ in (1435 mm) gauge line in 1867. The third track was installed to allow passengers and goods travelling over the 3 ft 6 in (1067 mm) gauge Staatsspoorweg (State Railway) a direct connection without requiring transfer at both cities. Later, a separate pair of tracks was installed at the government's cost to allow greater capacity and higher speeds. In 1940 a third rail was installed between Solo and Gundih on the line to Semarang, allowing 3 ft 6 in (1067 mm) gauge trains to travel between Semarang, Solo and Yogyakarta (via Gambringan, on the line to Surabaya instead of via Kedungjati on the original line). A short section of dual-gauge 3 ft 6 in (1067 mm) and 2ft 5½in (750 mm) line existed in North Sumatra on a joint line of the Deli Railway and the Aceh Tramway. This line survived in to the 1970s. Some sugar mill railways in Java also have dual-gauge sections. In Vietnam, there is dual gauge (meter and standard) between Hanoi and the Chinese border. In Sweden and Finland, there is about 4 km of dual gauge, 1435 and 1524 mm, between the railway stations in Haparanda and Tornio on each side of the border. In Los Angeles the Los Angeles Railway and the Pacific Electric Railway (both defunct) ran on dual gauge track on some downtown streets.
Page 252 of 259
6.5.5
Triple gauge
There have been a few instances of triple-gauge break-of-gauge stations:
Port Pirie, South Australia, 1067 mm, 1435 mm, 1600 mm (3 ft 6 in (1067 mm), 4 ft 8½ in (1435 mm), 5 ft 3 in (1600 mm)) (1938-1970) Gladstone, South Australia, 1067 mm, 1435 mm, 1600 mm (3 ft 6 in (1067 mm), 4 ft 8½ in (1435 mm), 5 ft 3 in (1600 mm)) (1970-1980s) Peterborough, South Australia, 1067 mm, 1435 mm, 1600 mm (3 ft 6 in (1067 mm), 4 ft 8½ in (1435 mm), 5 ft 3 in (1600 mm)) (1970-80s) Latour-de-Carol, France, 1000 mm, 1435 mm, 1668 mm (still in use)
Because these three triple-gauge examples were yards operating at low speed, light rail could be used to space the rails closely together if required. Main line operation at high speeds is another matter. The National Railway Museum (Port Adelaide) in Adelaide, Australia has the three main-line gauges and a 18 in (457 mm) gauge tourist line. The Niagara Falls Suspension Bridge originally carried trains of three different gauges.
6.5.6
Accidents on dual-gauge railways
On September 9, 2004, an accident happened on a switch in Jindřichův Hradec where dual-gauge railway bifurcates. A Junák express train from Plzeň to Brno derailed here because of a signalman's fault. He switched to the narrow-gauge track although the express train used the standard gauge one. Only the driver of the express train was slightly injured.
6.5.7
Complexity of dual-gauge switches
Dual-gauge turnouts (also known as switches or points), where both gauges have a choice of routes, are quite complicated, with more moving parts than single-gauge turnouts. They impose very low speed limits. If dual-gauge points are operated and detected by electrical circuits, their reliability will be high. Where two gauges separate (i.e. each gauge has only one route, as in the picture below), few moving parts are needed.
Figure 400: Switch - bifurcation of dual-gauge track near Jindřichův Hradec, Czech Republic.
Page 253 of 259
6.5.7.1
Paradox
If the two gauges of a dual gauge turnout are very similar and the difference between them is small, turnouts will have many small pieces that are difficult to support and the turnout will be weak and limited in speed. Paradoxically, the larger the difference the better. The difference between the gauges should as a rule of thumb be 50 mm greater than the width of the base of the rails. The three most common gauges in Africa when configured as above have relatively large differences between the gauges and the turnout will be relatively strong and its speeds will be reasonable. Conversely, the three gauges found on the borders of Afghanistan are too similar.
6.5.7.2
Gauge splitters
One way of avoiding complicated and weak dual gauge turnouts, provided there is room, is to separate the gauges and then design the yard with single gauge turnouts and dual gauge diamond crossings.
6.5.8
Separate gauge
If dual-gauge turnouts are too slow, or too difficult because the gauges are too similar, then an option is to build two separate lines, one of each gauge, side by side. This choice also depends on the amount of traffic. Dual-gauge could continue to be employed at an expensive bridge or tunnel. Examples include:
6.5.9
Albury, New South Wales to Melbourne, Victoria, 300 km: As the old and original broad gauge track declines in use, it is slated for conversion to standard gauge, replacing parallel standard-gauge single track and broad-gauge double track with a double-track standardgauge line. This will reduce delays on the standard-gauge line at crossing loops. Melbourne Victoria, to Geelong, Victoria, 80 km, a single standard-gauge line parallel to double-track broad gauge. Yogyakarta-Solo in Java, Dutch East Indies during pre-WW II days, 58 km. This had a single 3 ft 6 in (1067 mm) line paralleling a dualgauge 4 ft 8½ in (1435 mm) and 3 ft 6 in (1067 mm) line. In 2005 a proposed standard gauge line connecting Iran with China via several broad gauge Central Asian countries will use a mixture of parallel separate lines and dual gauge. Australia - in 1960, the Perth to Northam line was originally to be separate side-by-side narrow gauge and standard gauge lines, but it was realised that line capacity would be much higher if it were built as double dual gauge.
Overlapping gauges Bangladesh is tackling its break of gauge problem by adding a third rail to its broad and narrow gauge lines, so that it becomes a mainly dual-gauge system. The new Jamuna Bridge that links the east and west rail systems is four-rail dual gauge so that both gauges use the same centre-line. At some stage in the future, Bangladesh may choose one gauge over the other and convert to a single gauge, but there are no immediate plans. Bangladesh's neighbour to the east is also 1000mm gauge, should the missing link ever be built. A variation of overlapping gauge is to extend a railway of one gauge into territory that is mainly of another gauge so as to avoid transhipment of specific traffic. For example a 1524 mm gauge line from an iron ore mine in Ukraine to a steelworks in Slovakia, which now may be extended into Austria.
6.5.10 Other methods of handling multiple gauges Other methods of handling multiple gauges include:
Transporters wagons or transporters trucks, which carry equipment of one gauge on the other's tracks Truck exchange systems, where the railroad car is lifted and the trucks/bogies under it are swapped (not suitable for four-wheel wagons). Adjustable gauge equipment (variable gauge axles), in which the wheel gauge can be widened or narrowed Transhipment; transferring goods or people from one set of railroad cars to another\
6.5.11 Dual gauge dual voltage A mini-metro in Gijon, Spain is to be both dual gauge (1000 mm/1676 mm) and dual voltage (1500 V DC/3000 V DC). A dual-gauge track (Iberic: 1668mm-5ft6in; Standard: 1435mm-4ft8in) seen at Huesca station is the first application of the dual-gauge track tested in Olmedo in 2002. The single-track line Huesca-Tardienta has been rebuilt to high-speed standards and electrified in 25kV-50Hz ac, all cleared for 250kph. At a first stage, speed will be restricted to 160kph on that dual-gauge portion. One can see that the switch point is single-gauge only, for better cost-effectiveness.
Page 254 of 259
Figure 401: Dual gauge dual voltage
Figure 402: A dual-gauge track (Iberic: 1668mm-5ft6in; Standard: 1435mm-4ft8in) seen at Huesca station
Page 255 of 259
6.6 Variable (adjustable) gauge axles Variable gauge axles (VGA), developed by the Talgo Company and Construcciones y Auxiliar de Ferrocarriles (CAF) of Spain, enable trains to change gauge with only a few minutes spent in the gauge conversion process. The same system is also used between China and Central Asia, and Poland and Russia. Both China and Poland are on standard gauge, while Central Asia and Russia are on 1520 mm gauge. Possible reasons why the VGA system is not more widely used could include marketing and/or economics, unfamiliarity, conservatism and not enough space between the wheels to accommodate the mechanism from standard to narrow gauge,, especially to 3 ft (914 mm) gauge.
6.7 Break-of-Gauge With railways, a break-of-gauge is where a line of one gauge meets a line of a different gauge. Trains and rolling stock cannot run through without some form of conversion between gauges, and freight and passengers must otherwise be transloaded. Either way, a break-of-gauge adds delays, cost and inconvenience to traffic that must pass from one gauge to another. Transloading of freight from cars of one gauge to cars of another is very labour and time intensive, and increases the risk of damage to goods. If the capacity of freight cars on each system does not match, additional inefficiencies arise. Technical solutions to avoid transloading include variable gauge axles, replacing the trucks of cars, and the use of transporter cars that can carry a car of a different gauge. Talgo and Construcciones y Auxiliar de Ferrocarriles have developed dual gauge axles (variable gauge axles) which permit through running. In some cases, breaks-of-gauge are avoided by installing dual gauge track, either permanently or as part of a changeover process between gauges.
6.7.1
Inconvenience
Figure 403: Bogies exchange operation in Ussurisk (near Vladivostok) at the Chinese–Russian border.
Page 256 of 259
Figure 404: One solution to the break-of-gauge problem – the transporter car
6.7.2
Overcoming a break of gauge
Where trains encounter a different gauge (a break of gauge), such as at the Spanish-French border or the Russian-Chinese one, the traditional solution has always been transhipment — transferring passengers and freight to cars on the other system. This is obviously far from optimal, and a number of more efficient schemes have been devised. One common one is to build cars to the smaller of the two systems' loading gauges with bogies that are easily removed and replaced, with switching of the bogies at an interchange location on the border. This still takes a few minutes per car, but remains quicker than transhipment. A more modern and sophisticated method is to have multi-gauge bogies whose wheels can be moved inward and outward. Normally they are locked in place, but special equipment at the border unlocks the wheels and pushes them inward or outward to the new gauge, relocking the wheels when done. This can be done as the train moves slowly over special equipment. When transhipping from one gauge to another, chances are that the quantity of rolling stock on each gauge is unbalanced, leading to more idle rolling stock on one gauge than other. In some cases, breaks of gauge are avoided by installing dual gauge track, either permanently or as part of a changeover process to a single gauge. In other cases (in Spain) variable gauge axles are used.
6.7.3
Major breaks of gauge
Major breaks of gauge between large systems include: Africa Rail lines links by ferries on convenient rivers or lakes. Dar-as-Salaam is one of the few places in Africa where different gauges actually meet. Bangladesh Bangladesh has decided to resolve most of its break-of-gauge problem by converting most of its broad and narrow gauge tracks to dual gauge. China
China (standard gauge) on one hand, Mongolia and Russia (1520 mm) on the other. (Transmanchurian Railway) China (standard gauge), Vietnam (metre gauge) Thailand
Several countries bordering Thailand use meter gauge track, but there are missing links between Thailand and Vietnam via Cambodia.
Page 257 of 259
Vietnam Dual gauge (meter gauge and standard gauge) from Chinese border to Hanoi India India has decided to convert a significant proportion of the narrow gauge system to broad gauge since towns on the narrow gauge system used get a second-class service. Iran Iran with its standard gauge has break-of-gauge at the borders with Azerbaijan and Turkmenistan, and will soon have a new break-of-gauge with Pakistan. It has a short main line with tracks of Indian broad gauge. Australia
Queensland (1067 mm) and New South Wales (1435 mm) New South Wales (1435 mm) and Victoria (1600 mm) Southern South Australia uses broad gauge, like Victoria. Northern South Australia had a number of narrow gauge 1067 mm lines, leading to several break-of-gauge stations at various times including Hamley Bridge, Terowie, Peterborough, Gladstone and Port Pirie. In the latter part of the 20th century, all mainland capital cities were connected by a standard gauge (1435 mm) network, leading to more breaks of gauge (or branch line closures) in states where this is not the norm. Perth's railway system is narrow gauge (3 ft 6 in (1067 mm)), while the Indian Pacific is standard gauge. The line between East Perth and Midland, the eastern suburban terminus, and inland to the major rail junction at Northam is dual gauge. All rail east of this is standard gauge. Europe
France (1435 mm) and Spain (1668 mm) Poland, Slovakia, Hungary, Romania (1435 mm) and former Soviet Union countries: Russia (Kaliningrad), Lithuania, Belarus, Ukraine, Moldova (1520 mm) Finland (1524 mm) and Sweden (1435 mm), between Tornio and Haparanda. Railway ferries between Finland and Sweden or Germany. Switzerland, see "Minor breaks of gauge". North America
The United States of America had broad, narrow and standard gauge tracks in the 19th century, but is now almost entirely 1435 mm. Similar are the adjacent countries of Canada and Mexico. Latin America Argentina and Chile both use 1676 mm broad gauge tracks, but the link railway uses meter gauge with rack railway sections. So there are two breakof-gauge stations, one at Los Andes, Chile and the other at Mendoza, Argentina. It is planned to reopen this currently closed railway in summer 2007 and regauge from small to broad to be in future without break-of-gauge. A break-of-gauge (914 mm / 1435 mm) between Mexico and Guatemala is currently closed. A break-of-gauge between Argentina and Brazil, 1,435 mm (4 ft 8½ in) to 1 m (3 ft 33⁄8 in). A break-of-gauge between Uruguay and Brazil, 1,435 mm (4 ft 8½ in) to 1 m (3 ft 33⁄8 in).
6.7.4
Minor breaks of gauge
Wherever there are narrow gauge lines that connect with a standard gauge line, there is technically a break-of-gauge. If the amount of traffic transferred between lines is small, this might be a small inconvenience only. In Austria and Switzerland there are numerous breaks-of-gauge between standard-gauge main lines and narrow-gauge mountain railways. The line between Finland and Russia has a minor break-of-gauge. Finnish gauge is 1524 mm and Russian 1520 mm, but this does not stop through-running. The effects of a minor break-of-gauge can be minimized by placing it at the point where a cargo must be removed from cars anyway. An example of this is the East Broad Top Railroad in the United States of America, which had a coal wash and preparation plant at its break-of-gauge in Mount Union, Pennsylvania. The coal was unloaded from narrow gauge cars of the EBT, and after processing was loaded into standard gauge cars of the Pennsylvania Railroad. In addition to its broad-gauge lines, Spain has modern high-speed lines operating on standard gauge, and uses gauge converters. These railways are for passengers only and they have to change train, usually in big cities where they would have to change train anyway.
6.7.5
Other issues
While track gauge is the most important factor preventing through running between adjacent systems, other issues can also be a hindrance, including loading gauge, couplings, brakes, electrification, signalling systems, rules and regulations, and language.
Page 258 of 259
6.8 Future Further standardization of rail gauges seems likely, as individual countries seek to build inter-operable national networks, and international organizations seek to build macro-regional and continental networks. National projects include the Australian and Indian efforts mentioned above to create a uniform gauge in their national networks. The European Union has set out to develop inter-operable freight and passenger rail networks across the EU area, and is seeking to standardize not only track gauge, but also signalling and electrical power systems. EU funds have been dedicated to convert key railway lines in the Baltic states of Lithuania, Latvia, and Estonia from 1520 mm gauge to standard gauge, and to assist Spain and Portugal in the construction of high-speed rail lines to connect Iberian cities to one another and to the French high-speed lines. The EU has also developed plans for improved freight rail links between Spain, Portugal and the rest of Europe.
6.8.1
High speed
All high-speed rail systems around the world have been built using or planning to use standard gauge, even in countries like Japan, Taiwan, Spain and Portugal where most of the country's existing rail lines use a different gauge. (Exception: Russia and Finland has 5 ft high-speed rail, very recent). Once standard gauge high-speed networks exist, they may provide the impetus for gauge conversion of existing passenger lines to allow for interoperability. All high speed lines have adopted 25 kV, 50 Hz AC., Overhead Line as the standard electrification system, except Germany, Sweden and Switzerland (15 kV AC) and the first high speed lines in Italy (3000 V DC).
6.8.2
Mining
Mining railways with little interconnection with other lines also tend to choose standard gauge to allow use off the shelf equipment, especially of the heavy duty kind. The United Nations Economic and Social Commission for Asia and the Pacific (UNESCAP) is planning a Trans-Asian Railway that will link Europe and the Pacific, with a Northern Corridor from Europe to the Korean Peninsula, a Southern Corridor from Europe to Southeast Asia, and a North-South corridor from Northern Europe to the Persian Gulf. All the proposed corridors would encounter one or more breaks of gauge as they cross Asia. Current plans do not call for widespread gauge conversion; instead, mechanized facilities would be built to move shipping containers from train to train at the breaks of gauge.
6.8.3
Kenya-Uganda-Sudan proposal
A proposal was aired in October 2004 to build a high-speed electrified line to connect Kenya with southern Sudan. Kenya and Uganda use 1 m (3 ft 33⁄8 in) gauge, while Sudan uses 3 ft 6 in (1067 mm) gauge. By choosing standard gauge for the project, the gauge incompatibility is overcome. A bonus is that Egypt, further north, uses standard gauge. Since the existing narrow gauge track is quite likely of a "pioneer" standard, with sharp curves and low-capacity light rails, substantial reconstruction of the existing lines are needed, so gauge unification would be sensible.
6.9 Rail sizes Rails in Canada, the United Kingdom, and United States are still described using imperial units. However, in Australia they are now described in metric units and always have been on mainland Europe. Depending on the use of imperial or metric units, rail sizes are usually expressed in terms of pounds per yard or kilograms per metre. Coincidentally, the pounds-per-yard figure is almost exactly double the kilograms-per-metre figure, making rough conversions easy. Rails are made in a large number of different sizes. In the countries of former USSR 65 kg/m rails are common. Thermally hardened 75 kg/m rails also have been used on heavy-duty railroads like Baikal-Amur Mainline, but have proven themselves deficient in operation and were mainly rejected in favour of 65 kg/m rails. 50 kg and 60 kg are the current standard, although some other sizes are still manufactured. Some American sizes are used on northwest Western Australian iron ore railways.
6.10 Track maintenance Track needs frequent maintenance to remain in good order; the frequency increases with higher-speed or heavier trains. Without frequent maintenance, a slow zone may occur due to damage on the tracks. Track maintenance was formerly hard manual labour, requiring teams of labourers (US: gandy dancers, GB: plate players), who used levers to force rails back into place on steep turns, correcting the gradual shifting caused by the centrifugal force of passing trains. Currently, maintenance is facilitated by a variety of specialised machines. The profile of the track is maintained by using a rail grinder. Common maintenance jobs include spraying ballast with weed killer to prevent weeds growing through and disrupting the ballast. This is done with a special weed-killing train. Over time, ballast is crushed or moved by the weight of trains passing over it, and periodically it needs to be levelled (tamped) and eventually cleaned or replaced. If this is not done, the tracks may become uneven causing swaying, rough riding and eventually the risk for derailment. Rail Inspections utilize non-destructive testing methods to detect internal flaws in the rails. This is done by using specially equipped HiRail trucks, inspection cars, or in some cases handheld inspection devices. Broken or worn-out rails also need replacing periodically. Mainline rails that get worn out usually have life left in branch line or rail siding use and are "cascaded" to those branch lines.
Page 259 of 259
