Modern Developments in Turnouts Including Aspects of Maintenance
PROJECT BY: Sri N. K. Agrawal, Dy.CE/TM/SER Sri S. K. Gupta, Sr.DEN/2/DNR Sri R. K. Singh, Dy.CE/TP/SECR Sri Balbir Singh, Dy.CE/Land/N Dy.CE/Land/NR R DIRECTED BY: Sri Manoj Arora, Professor (Works) COURSE NO. 821, January -2008
Modern Developments Developments in Turnouts Including Including Aspects of Maintenance Maintenance
Sr. No.
Index
1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.
Synopsis Kinematic Gauge Optimization Self Lubricating Switch & Slide chair Materials Austroroll Switches Divided sleepers in crossing portions Canted Running Table Remote Switch Controllers and Monitors Curved Gauge Crossings Swing Nose Crossings Explosion Depth Hardened CMS crossing Weldable CMS crossing Thickweb Switches Heat Treated Switch Tips Design consideration for high speed routes on IR A typical design for high speed turnout for IR Maintenance aspects of existing fan shape turnouts on IR Postscript
17.
1
Page No. 2 2 4 4 5 6 6 8 8 11 11 12 13 14 15 16
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1.0 SYNOPSIS: In terms of development in track technology vis-à-vis points and crossings, Indian Railway presents a study in contrast compared to other Railways of the world. In Indian context, the state of the art turnout permits a speed of 160 kmph on straight route and 50 kmph on turnout, design being 1 in 12 fanshape layout. On the other hand, on TGV Atlantic, a Modern Turnout permits a speed of 501 kmph on straight track with speed potential on turnout side being 230 kmph, design being from VOSSLOH COGIFER stable, with cast manganese crossing, having curved gauge face, swing nose, canted running table, switch entry angle in the range of 5’ to 6’, switch taking off tangentially. Though, our stubbornness to stick to the existing yard layouts at the time of switching over to PSC layouts have restricted speed potential of our turnouts to 50 kmph and further stubbornness to sticking to the same three aspect signals while switching over to modern signaling system (PI/ RRI/ SSI, you name it, we have it) further restricting this speed to 30 kmph, a question can be asked as to the need of venturing into un-chartered territories of supersonic speed. However, to modernize the Indian Railway track for coping with the increased speed and Heavy Axle Load (HAL) with DFC and more recently, high speed corridors being more of a reality, the technical know how of modern developments in the field of points and crossings becomes imperative. Such an effort also provides us insight as to what can be done to our existing turnouts so as to make it more reliable, better running, requiring less maintenance at the existing speed of 130 to 160 kmph. It is a fact that as on date, with PSC layout and mechanized maintenance, the only inferior running area on our track is points and crossings. Whether it is footplate inspection note of AEN or window trailing inspection note of PCE or recording of OMS/ TRC, all tell the same story. This has got as much to do with the maintenance practices as also to do with the structural problems of the turnout assembly. In the subsequent paragraphs, we have made a humble effort to study developments taking place in turnout design vis-à-vis improvements required in the points and crossing assembly both on existing layouts as well as in future sections like DFC/ HSC, both through improved components/ designs as well as improved maintenance practices. 2.0 KINEMATIC GAUGE OPTIMIZATION:
In high speed turnouts, the most susceptible part prone to damage is switch and that too on reverse side, owing to its’ reduced section and increased angle of attack due to curvature, wheel moving with a positive
2
angularity on the reverse side of turnout. The problem becomes more severe, if the reverse side is also leading to other main line. At higher speed, design of switch is guided not only by geometry considerations, but also by rail wheel interaction on real time basis. The concept of switch geometry optimization by using Multibody-dynamic vehicle simulation as massspring-damper-system and track with variable sections, Computer Aided Design and Finite Element analysis to arrive at optimization of switch layout. Various Switch Geometry Optimization theories in vogue are KINEMATIC GAUGE OPTIMISATION, Layout Geometry (e.g. circular, spirals, patented asymmetric clothoids) and Wheel Contact Geometry (Delta-Kappa, constant rolling radius difference for different wheel positions). KINEMATIC GAUGE OPTMIZATION envisages undisturbed passage of wheel on the rail in a consistent sinusoidal wave pattern; so as to avoid/ minimize wheel flange contact with gauge face of switch through out the movement. This concept requires computer modeling for a given situation and as such cannot be a GENERAL SOLUTION. However, companies like BWG are providing end-to-end solution, from design to product to installation, for high speed corridors. Such a solution, minimize contact of wheel flange with rails thereby, permitting higher speed as well as resulting in minimal wear of switches. This has a “SELF STEERING EFFECT” on the running vehicle. In case of India, a close parallel of this concept is THICK WEB SWITCHES, where, a small part of switch remain free from wheel flange contact.
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3.0 SELF LUBRICATING SWITCH & SLIDE CHAIR MATERIAL: Normally, in case of switches, to avoid wear as well as for ensuring smooth switch operations free from failure, lubrication is must. In case of high speed corridors, where un-interrupted traffic flow is required, such failures can have serious impact. To ensure hassle free switch operation, experiments have been done at metallurgical level and switches and switch tables have been developed with materials which have got such particulate properties, which obviate the need of external lubrication all together. As human element involved in lubrication is totally eliminated, failure of switch operation on this account is obviated. Further, the very characteristic of the material reduces rail-wheel friction co-efficient also, thereby reducing wear as well as increasing safety. The same is environment friendly also as no lubricating material is involved. This has been used on German Railways. 4.0 AUSTROROLL SWITCHES: Another solution to lubrication problem has been provided by the company Enzesfeld-Caro Metallwerke AG. The company has developed an innovative Austroroll® roller device. This is an innovative maintenance free switch point system that improves the reliability, cost and environmental impact of railways. The use of high-strength, weather-resistant materials ensures that the Austroroll has a rigid design. The design guarantees Austroroll's longevity and operational safety. In the closed position the switch rail rests on the slide chair. When the point is switched it is lifted from the slide chair on which it rolls smoothly into the open position. Due to non-requirement of lubrication, there is no need to dispose of oilcontaminated track material and neither is there any lubricant or lubrication labour cost. The technology makes sure the switch rail is brought fully into the closed and open position.
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5.0 DIVIDED SLEEPER IN CROSSING PORTION: This is a common observation of P. Way Engineers that retentivity of tamping is low in case of crossing sleepers. In India, we believe that this is mostly on account of fish plated joint in foreleg and backleg of crossing, impact due to gap at nose of crossing and lateral forces due to curvature of turnout. However, even with use of curved swing nose crossing with canted running table, this problem of loose packing was found to persist in high speed corridors. It was observed that long length of crossing sleeper was to some extent responsible for poor maintainability of crossing area, due to undamped vibration of long sleepers under impact load of high speed trains. Certain design of divided crossing sleepers have been developed, which is jointed though a mechanical system. The jointing system is designed in such a fashion that it dampens the vibration, which has the affect of improving longevity of tamping as well as lowering attrition of ballast.
FIGURE SHOWING JOINTED SLEEPEERS IN CROSSING AREA
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6.0 CANTED RUNNING TABLE: On Indian Railway, track assembly has been provided with 1 in 20 cant. However, on points and crossing, plane running table has been provided, decanting being provided with the help of approach sleepers of fanshape layout. This works well with NORMAL SPEEDS. However, at higher speeds, plane running table poses problem in ensuring sinusoidal movement of moving trains with flatter conicity (1in 40 to 1 in 60). Now, technology has been developed whereby canted running table can be provided in points and crossings also. DMRC has used canted turnouts in their project using 60D rails. This rail has special feature of flat bottom and top canted to 1:20. Stock rails are made canted by giving 1:20 cant in slide chairs. 7.0 REMOTE SWITCH CONTROLLERS AND MONITORS:
Switch controllers are device which enables switch blades to move for change of direction. In case of fan shape layout of IR, this controlling is done with the help of pull applied at toe, integrity of switch blade movement being ensured though stretcher bars at two locations. The pull is applied either mechanically or through electrical means. Modern point machines are having integrated pull and interlocking mechanism also. However, even with comparative large switch entry angle and corresponding smaller length of switch blades, single location pull does not result in proper housing and setting of tongue rails up to JOH. In case of 1 in 12 turnouts, we have been providing SSDs for solving this problem. On high speed corridors, where turnouts are much flatter, say 1 in 43 turnout of SNCF, with corresponding much larger length of switch blade, such single location pull will not work. In such locations, switch controlling is multi-point through electrical or electromagnetic means. Also, traditional switch controlling systems are mounted on turnout assemblies itself. But, mounting such devices at 10-11 drive locations are not feasible. In recent times, new type of integrated hydraulic switching and controlling devices have been developed to cater for requirements of high speed turnouts. In such systems, pull is through hydraulic circuits, and locking system is also integrated in hydraulic setting cylinders. These system require no lubrication or maintenance inputs. The operation is also through remote operational posts, obviating the need of mounting the controlling unit on turnout sleepers. One such commercially operational system on European Railways is the HYDROSTAR Hydraulic Setting System which can drive up to twelve adjustment positions via a hydraulic drive system. The Hydraulic Setting Device HYDROSTAR can be pre-assembled, adjusted and tested in the workshop and plug-and-play delivered to the track. The track laying of the pre-assembled turnout can be
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done in a very short time. Easy, quick and low maintenance of the system causes low LCC, high safety and reliability of the turnout. HYDROSTAR is an integrated modular solution for each required function of the system: Integrated in a Hollow Sleeper, makes machine tamping of switch device possible Encapsulated Locking (SPHEROLOCK-principle) •
•
•
•
Hydraulic Transmitting mechanical connection rods)
(HYDROLINK-principle,
replaces
Electronic Detection by VAE IS 2000
Monitoring of the switches on such high speed corridors are through Electronic remote turnout monitoring system (commercial example being VAE ROADMASTER 2000). Combination of remote switch controlling and operation makes these turnouts intelligent turnouts. On a smaller scale, yards having RRI/ PI do represent intelligent turnouts on a smaller scale, but the inability to monitor complete routes through remote, as is the case on IR, is done away in such systems. Contact less inductive and strain gauge sensors measure, monitor and report the condition of the turnout's critical items on entire stretches/ routes. The VAE ROADMASTER 2000 Turnout Monitoring System continuously measures the operating status of a set of turnouts and communicates this data to a monitoring centre. Whole stretches of rail track can be monitored centrally in this manner. Condition based planning of maintenance helps to increase safety and availability of track, the productivity of the railway company and to optimise the use of spare parts.
The Hydraulic Setting Device HYDROSTAR with integrated locking, hydraulic transmitting and electronic detecting is located in a hollow sleeper which makes machine tamping of switch device possible. 7
8.0 CURVED GAUGE CROSSING:
Any discussion in IR on the possible causes of low speed on our turnouts almost always has one item as straight gauge face of crossings, either built up or CMS. Due to non transitioned movement of wheel from curved lead to straight crossing leads to jerk at such location. However, on high speed corridors, every where only curved gauge face crossings are being used. As the type of crossings being used on high speed corridors are almost always swing nose crossings, hence, swing nose crossings with curved gauge faces are existing on such high speed corridors. Figure below shows one such swing nose crossing with curved gauge face, produced by VOSSLOH COGIFER.
However, it may not be out of place to mention that technology of curved gauge face CMS crossing is also existing in the realm of possibility, one such firm being VAE – VKN. Dr. M. Sheshagiri Rao is of the opinion that higher speed than 50 kmph can be achieved on 1 in 12 turnouts of IR using curved gauge face crossings. 9.0 SWING NOSE CROSSING:
In case of fixed nose crossings, the tread of the moving wheel drops by about 3 mm while traveling between throat and actual Nose because of 1:20 cant of the wheel-tread. During further onward movement of the axle, the wheel-tread suddenly climbs up by 3 mm while moving from actual Nose to the Vee of crossing within a short distance of about 100 mm. Such sudden climbing within a very short time causes severe vertical accelerations in the
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axles. Correspondingly, it results in large vertical reaction in the CrossingNose region. The magnitude of the vertical load on the nose of crossing
SWING NOSE CROSSING WITH SPECIAL MANGANESE BASE PLATE
depends on the square of the speed of vehicle and the static axle-load. Such high vertical loads lead to severe impacts and result in heavy wear and fatigue damage to the nose and wing rails in the proximity of actual nose. While the wear is visible to the naked eye, the fatigue damage continues to remain unnoticed. Therefore, its full significance escapes the attention. The surfaces of nose and wing rails which suffer heavy wear have to be routinely resurfaced/ rebuilt by welding at intervals of about 6 to 9 months. Though such rebuilding of worn surfaces is possible, there is no known process for healing the internal fatigue damage suffered by the crossing material under severe impacts. As such, the entire crossing has to be scrapped within 3 to 4 years of service (after resurfacing about 4 to 6 times). Swing Nose crossings offer a possible solution to this problem. In this crossing, the wheel-tread runs on a continuous surface of rail-head without encountering any vertical drop in actual nose region. As a result, vertical accelerations and resultant rapid wear/ fatigue damage are almost totally eliminated. It would be logical to assume that the service life of such a crossing would increase manifold. The first 1:12 Broad Gauge 60 kg SNC was laid on Indian Railways on th 29 July 1997 near Tatanagar railway station. 100 Sets of SNC crossings
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were supplied by BMW to Central, Eastern, Northern, South Eastern and Western Railways. The SNCs laid are performing to the satisfaction of field-staff of Engineering Department. Necessary point-locking equipment and ground connections for the SNCs were also evolved and supplied by BMW as desired by Indian Railways. Indian Railways had also procured 20 Nos. of foreign turnouts with SNC. Advantage of Swing Nose Crossings (SNC) compared to CMS crossings are as under: •
•
•
•
•
•
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) No check rails required – a condition for high-speed traffic Reduced airborne and structure-borne noise Highest possible service life because there are no impacts in the wheel transition area Can be thermit welded into the track With special anti-creep equipment for transmission of longitudinal forces in the continuously welded track.
However, it is interesting to note that where as for high speed corridors, preferable solution is almost always swing nose crossing, for heavy haul routes, the preferred choice is almost always CMS crossings. Due to universalization of heavy haul operations (CC+6, CC+8 etc.), Indian Railway has decided to universalize WELDABLE CMS CROSSINGS on A & B routes. Already global tender for “Manufacturing and Supply of Weldable CMS crossing with its’ reconditioning” has been invited by Railway Board. It is expected that in the envisaged high speed corridors, preferred choice of crossing type will be SWING NOSE CROSSINGS only. It is further interesting to note that VOSSLOH COGIFER has developed technology for SNC made of CAST MANGANESE STEEL as well. Such SNCs have been tried at speeds of even 501kmph in straight and 230kmph in reverse.
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10.0
EXPLOSION DEPTH HARDENED CMS CROSSING:
CMS Crossings being used on the track of Indian Railways have the surface hardness of 180-220 BHN and under traffic load leads to metal flow on the top running surface, hence adversely affecting the service life and comforts. In order to seize this tendency of metal flow to crop up appreciated increase in life span and service comforts, the surface hardness of the top surface needs an increase to the range of 330 – 360 BHN, which can be achieved by imparting “Explosion Depth Hardening” (EDH) process. Through application of the ‘EDH’-process, the total life of the CMS Crossing can reach up to double its conventional life, in addition to the improved dimensional stability and other structural benefits. In the absence of ‘EDH’ technology in India so far, the above enumerated benefits could not be availed of so far. Now, however this technology is readily available to VAE-VKN through its partners VAE and JEZ. 11.0
WELDABLE CMS CROSSING:
This is the most important innovation in the CMS crossing domain, reputed for their high resistance. Weldable CMS crossing consists of 3 parts i.e. the CMS crossing casting; an intermediate piece and connecting rail. The rail is first welded to the intermediate piece, which in turn is welded to CMS crossing casting.
Technology of welding of CMS crossing with normal rail was developed by European Countries during eighties. IR imported 20 turnouts with weldable CMS crossings earlier. These turnouts were laid in Allahabad Division of NR and performance was found to be highly satisfactory in 11
terms of maintenance efforts, riding quality and wear performance. The problem like working out of GRSPs, hammering at crossing joint, damage of crossing sleeper etc. were highly mitigated in such crossings. Accordingly, IR decided to lay weldable CMS crossings to eliminate fish plated joint and to provide continuous path for smooth running. Use of weldable CMS crossing will provide improved safety as fish plated joints are always fracture prone apart from vulnerable to sabotage. Intermediate piece is used for welding of CMS crossing with normal rail. This piece has such metallurgical properties so that it can be welded with normal rail as well as CMS crossing (17-19% Cr & 9-12%Ni). This intermediate piece is either cast or rolled to the shape of rail having dimension slightly more than normal rail. Intermediate piece is first welded with normal rail by flash butt welding method. This piece is then cut to length of 20-30mm. Chiseling, grinding and post heating are done after welding as per requirement. 4 such rails are welded with ends of CMS crossing by same method. RDSO has designed weldable CMS crossings for 1 in 12 and 1 in 8½ by increasing the length at toe and heel ends and matching the profile of normal rail so that welding is possible with intermediate piece. Drawing NO.RT-6412 and RT-6441 of 1 in 12 and 1 in 8 ½ weldable CMS crossing have been issued by RDSO. Now two firms (VAE-VKN, Sonepat & Beekay Engineering & castings, Bhilai) are manufacturing weldable CMS xing for supplying on trial basis. Also, IR has now standardized weldable CMS crossing for all heavy axle routes . Already, one global tender for supply and re conditioning of 7500 weldable CMS crossing have been invited by IR for this purpose. 12.0
THICKWEB SWITCH:
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In conventional switches, the foot of the tongue rails sit over the foot of stock rail. This creates twist which causes discomfort in riding. To overcome this problem, switches are being manufactured with asymmetrical rail in European countries. Asymmetrical rails have about three times more web thickness than symmetrical rails and hence the name thick web switches. The switches with these asymmetrical rails have more rigidity and greater strength. Also, the switch is housed in recessed stock rail. Hence, there is practically no wear of such switches. Two types of thick web switches are used by Indian Railways Zu-2-49 FOR 52KG and Zu-1-60 FOR 60KG. These switches have service life of 300-600 GMT which is more than 10-12 times of normal switches. KRCL has procured 320 sets of Zu-2-49 for PSC sleeper layout with 145mm throw with SSD. Performance of these switches on KRCL is satisfactory. 400 sets Zu-1-60 TWS were procured in 19962000 for PSC sleeper layout with 160mm throw and SSD. Use of SSD enable uniform gauge in switch portion, thus avoiding floating tight gauge and rattling of switches and stretcher bar fittings. RDSO has developed design of 1:12 and 1:8.5 TWS with 160mm throw and SSD on PSC sleepers. Also, IR has now standardized TWS for all heavy axle routes. Already, one global tender for supply of 10000 thick web switches have been invited by IR for this purpose. RDSO’s design for slide chairs for TWS is with ERC, leaf spring and wedge arrangement. This is a very good system of fitting which do not become loose under impact load of running traffic. TWS do not undergo wear and require little maintenance work. Also, there is no twist as top of the tongue rail is in level with top of stock rail. TWS has got high lateral strength and are sturdier due to thicker web. There is smooth entry due to reduced switch entry angle. Jerk at entry is reduced as tip of tongue rail is housed in a recess. TWS also has got higher speed potential (50 kmph).
13.0
HEAT TREATED SWITCH TIPS:
The tongue rails normally get chipped off in a thin portion (up to 2000 mm) from ATS. The worn out tongue rails need precise and accurate reconditioning to ensure proper profile to match with stock rails. Due to rapid wear at the toe of tongue rails, frequent renewals are required. It increases maintenance cost and requires traffic block to recondition worn out tongue rails. HEAT TREATED SWITCH (HTS) Tip is a part of tongue rail 13
fitted with web of tongue rail after stubbing. It covers the area of tongue rail which are prone to wear. This length is about two meter from ATS. Normally, tongue rails wear in about two meter length from ATS and the rest of tongue rail has no wear but every time complete tongue rail is replaced. Tongue rails fitted with HTS tips need to be replaced the tip portion only and there is no need to replace full tongue rail. Worn out switch tips after reconditioning may again be fitted on stubbed tongue rails. The wear pattern observed on HTS tips are very negligible. Being heat treated, it causes negligible wear of tongue rail. Tongue rails fitted with HTS tips will have long service life. Use of HTS tip will avoid frequent renewals as well as lesser frequency of reconditioning of worn tongue rails. Central Railway had procured few sets of 10125mm curved switches fitted with HTS tips for BG 60Kg and 52KG for PSC layouts. These switches laid in sub-urban section of Central Railway and performance has been satisfactory.
REINFORCING STRAP TONGUE RAIL SWITCH TIP STOCK RAIL
REINFORCING STRAP TONGUE RAIL SWITCH TIP STOCK RAIL
SECTION AT END
14.0
SECTION AT TOE
DESIGN CONSIDERATION FOR HIGH SPEED ROUTES ON
IR: As discussed in foregoing paragraphs, considerable progress has been made world over in turnout technology, industry being at the forefront in bringing out new technology as and when need for higher speed arose. Any proposed high speed corridor on IR (as announced by PM), will have to rely
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heavily on such technologies. A broad technical frame work for such a turnout has been outlined in following lines. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15.
Flatter entry angle thereby reducing the angle of attack and reduced lateral forces resulting in increased passenger comfort. Adoption of tangential layouts providing benefits of higher speeds. Introduction of transition curves thereby improving the running characteristics of the curved tracks. Use of spring operated switch setting device to ensure proper flange way clearance. Use of movable nose crossings, thereby avoiding gap at crossing. Use of swing nose crossings, housed in a specially designed cradle Use of asymmetrical profile section (ZU-1-60) forged to standard rail profile (UIC 60) at the end. Continuation of canting of rails through turnout resulting in smoother ride over turnouts. Use of higher UTS steel, further hardened to reduced wear. Effective holding of stock rail . Use of non greasing eco friendly base plates. Use of specially designed synthetic rail pads for reduced vibration of switch assembly. Provision of thermal restraints to arrest differential thermal expansion of stock and tongue rails. Sophisticated pulling techniques including introduction of hydraulic systems. Surface hardening of load bearing areas.
15.0 A TYPICAL DESIGN FOR HIGH SPEED TURNOUT FOR IR: Based on above technical framework, a typical layout for a high speed turnout (Proposed for 250 kmph) has been developed by Sr. Professional Course Trainees earlier. Underlying design parameters and detailed calculations are available on IRICEN website, but the same has not been incorporated here, as the same is not in the scope of this project. Speed Maximum Cant Deficiency Variation of Cant Deficiency Radius of lead Curve
= = = =
250 Kmph 85 mm 30 mm/sec 10130 M
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Gauge Switch Entry angle Switch Length
= = =
Tangential switch Length
=
1676mm 0-04-23 44.633 mtr (Flexible Part = 43.793 mtr) 4.299 mtr
Circular switch Length
=
18.963 mtr (for increased radius
Parabolic switch Length
=
Crossing Length Angle of crossing Total Length of the turnout
= = =
16.0
of 10130 m) 21.371 mtr (for increased radius of 10130 m) 27.00 mtr 1 in 65 215 mtr
MAINTENACE ASPECTS TURNOUTS ON IR:
OF
EXISTING
FANSHAPE
On IR, existing turnouts are 1 in 12, 1 in 8.5 and at some locations 1 in 16 on fan shape layout. When the design of fan shape layout was adopted on IR, it was presumed to be a fit and forget type of layout. But, far from this, the performance of these layouts has been ridden with problems. These problems are associated as much with design as with maintenance practices. As per recent policy decision, now on all A and B routes including heavy axle load routes, thick web switches and weldable CMS crossings have been made universal. Railway Board has already invited global tenders for these two items. With replacement of existing switches and crossings with thick web switches and weldable CMS crossings, large nos. of problem associated with fanshape layout will go away. However, the universalization of thick web switches and weldable CMS crossings is going to take much time. Further, there are other aspects also, which will keep giving trouble to P. Way Engineers. In subsequent paragraphs, some of the problems associated with fan shape layout and possible solutions thereof have been discussed. 16.1Corrosion of Screw Spikes in Switch portion Screw spikes in switch portion are getting frequently corroded due to accumulation of dust, water, foreign materials etc. in between screw spike and polyethylene dowel. The situation becomes severe in corrosion prone yards having more number of passenger trains in early morning and evening.
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Due to excessive corrosion of screw spikes, its section reduces and also it gets broken while removing and thus makes sleeper damaged or ineffective. Remedial measures suggested: 1.1.Using galvanized screw spikes. 1.2.Applying anti corrosive paint to screw spikes during initial laying. 1.3.Frequent examination of screw spike and greasing/ applying anti corrosive paint. 1.4.Cost of 233 screw spikes @ Rs.22 per screw spike in one set of 1 in 12 T/O comes to Rs.5126. Cost of T/O sleeper per meter length is approx. Rs.850. Cost of screw spike is very less in comparison to cost of sleeper, hence to avoid any damage or being sleeper ineffective, screw spikes may be frequently renewed. 1.5.Filling dowel hole with proper grease and then inserting and tightening screw spike. 16.2Displacement of GRSPs in the middle portion of slide chairs Rubber pads under slide chairs are held by screw spikes at four corners. It is observed that the rubber pads in the middle portion of the slide chairs are getting disturbed in the direction of the train movement. At this juncture, the rubber pads come in contact with grease, which lead to faster displacement of the rubber pads. This problem has been observed mainly in sleeper nos. 4 to 15. Remedial measures suggested: ii) Pasting rubber pad with glue/ epoxy to sleepers. iii) Increasing thickness of GRSP from 6mm to 10 mm. iv) Replacement of GR by reinforced elastomeric material or by suitable high strength damping material, as being used on high speed corridors. 16.3Breakage of Gauge Tie plate around the base of stopper There have been instances of breakage of gauge tie plate around the base of stopper on sleeper no. 3 of the T/O. This is due to heavy thrust encountered by the stock rail at the toe of switch. Remedial measures suggested: i) Suitable pre curving of stock rail at the time of laying of Turn Out. ii) Improved welding and sturdy design.
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16.4GRSPs getting displaced in lead rail portion and under CMS xings. It is observed that rubber pads are getting displaced in lead rails as well as under CMS crossing portion. Also, wear in rubber pad is faster especially under CMS crossings. If the rubber pads get worn out and are displaced from under side of rail seats, the rail seat on PSC sleepers would get damaged, which would require replacement of PSC sleeper. In view of this it is urgent to under take suitable preventive steps to avoid such a situation. Remedial measures suggested: i) ii) iii) iv) v) vi)
Perfect laying of Turn Out. To provide rubber pads with horns. Elastomeric pads can be tried in place of GRSP. Rubber pads may be pasted to PSC sleeper with suitable adhesive (epoxy). Ensuring proper packing of sleeper and full fittings. Providing and ensuring gapless joint during service between tongue rail - lead rail, lead rail – CMS crossing and CMS crossingrunning rail.
16.5Joint at the Junction of Tongue and lead rail This joint at present remains fish plated as per provision of manual. The joint at the Junction of Tongue and lead rail result in heavy stress and vibration in switch and lead rail portion. This causes battering of joint, breakage of switch fittings, crushing and shifting of rubber pads, damage of PSC sleepers and ultimately disturbing parameters of T/O. Remedial measures suggested: i) ii)
Providing and maintaining gapless joint. Exploring possibility of allowing welding of this joint.
16.6Joint at the backleg and foreleg of CMS crossing. The joint at the backleg and foreleg of CMS crossing result in heavy stress and vibration in crossing portion. This causes bad running, loose packing, fish plate fracture, wear of inserts, loss of toe load of ERCs, wear and shifting of rubber pads, grooving and damage of PSC sleepers. Remedial measures suggested: i) Providing and maintaining gapless joints by adopting improved design of gapless joint by inserting proper thick ferrules in fishplate hole and rail hole. 18
ii)
Use of weldable CMS crossing.
16.7Drainage and ballast cushion. Proper ballast cushion and drainage at T/O improves riding qualities and better retention of track geometry. Ballast must be deep screened at the time of laying of T/O, because after laying it becomes difficult to deep screen ballast. Proper ballast cushion should be ensured during deep screening. Proper longitudinal and cross drains should be provided to ensure that there is no stagnation of water .For ensuring adequate cushion during service and to avoid center bound T/O sleepers, midlife deep screening is suggested. 16.8Damage of some isolated sleepers of turnout assembly. PSC T/O sleepers in crossing area gets damaged due to vibration and high impact load on crossing due to presence of gap at fore leg and back leg of crossing. Vibration in crossing portion displaces rubber pads and subsequently due to continuous impact groove forms on sleeper or sleeper gets cracked. Remedial measures suggested: i) ii) iii) iv) v) vi)
Providing gapless joint at crossing. Using 10mm thick GRSP in place of 6mm. Trying elastomeric pad in place of GRSP. Need based packing of sleepers. Replacement of damaged sleepers. The cost of sleeper is high and further sleeper manufactures avoid manufacturing of isolated sleeper as their production capacity hampers in producing isolated sleepers, therefore epoxy treatment of grooves in the sleepers is suggested as tried in Southern Railway successfully.
16.9 Problem in maintenance of stipulated gap between leading stretcher bar and rail bottom. As per manual there should be gap of 1.5 mms between leading stretcher bar and bottom of rail. Although this parameter is very useful in avoiding breakage of tongue rail tip and two route of wheel, it is very difficult to maintain gap of 1.5 mm on both side of track due to some twist, impact and thrust on switch portion.
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The remedial measure is to 1) Inspect and attain this periodically using washer. 2) Improving design of stretcher bar assembly in consultation with S&T. 16.10 Problem in housing and setting of tongue rail up to JOH. The fan shape layout envisages provision of spring setting device (SSD) in the switch assembly, but in field ,few SSDs are now being supplied only recently. In the absence of SSDs, housing of switch is not proper. Efforts should be made to provide all the fan shape layouts with SSDs. Also, the design of fan shaped layout envisages double stretcher bar with motor operation for ensuring perfect setting up to JOH, but in the field, this requirement is not always complied with. In the absence of perfect setting, the wear of switches is very high and will necessitate premature replacement. Further field experience suggests that the replacement of straight tongue and curved stock rail are much higher than that of curved tongue and straight stock rails, therefore efforts need to be made to asses the differential requirement and arrange for this differential supply of tongue rails and stock rails to cope up with maintenance requirement. Recently SECR has invited tender for supply of loose tongue rail and stock rail. 16.11 Problem in track Geometry correction post laying. It is very difficult to change parameters of a fanshape layout like three point offset of tongue rail – curved lead assembly etc. once laid incorrectly. For ensuring proper geometry, due care is required to be taken at the time of laying. Pre-bending of stock and lead rail in case of laying on curve, checking curvature of stock and tongue before laying, proper spacing of sleepers etc. should ensured so as to ensure proper design parameter post laying. In case of misalignment of existing layout, proper fixing of SRJ and overall length should be calculated and validated in the field before actual replacement.
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16.12 Codal provision related to stock rail and tongue rail wear, issue related to measurement. The present T/O inspection Performa is too lengthy and many items being measured have no such importance. No templates for measuring wear of tongue and stock rails have been provided in field. There is no specific wear limit of stock rail, this being same as that of normal side wear of rail. But, a wear of more than 3mm will lead to failure of switch setting in bead test. The conditions of fittings in T/O portion are being judged visually only. These issues are required to be addressed so as to make the inspection and post inspection attention meaningful. 17 Postscript: As rightly pointed out Dr. M. Sheshagiri Rao in one of his presentations th at RDSO on 7 July, 2006; the problem with Indian Railway as far as speed potential of turnouts is concerned, is not so much of design, but as much of mind set. We have continued with un-equalized length of tangents, where as the world over, equalizing length of tangents are being used for turnouts, thereby with same 1 in 12 layout permitting speed in the range of 80 - 100 kmph on reverse side, as compared to 30 – 50 kmph as possible on IR. What has been written in foregoing paragraphs is existing not only in realm of knowledge, but in the realm of practice. For adopting these modern technologies, what we need is a break from the fixed mind set and go for out of the box thinking. The same is neither required nor practicable on existing routes of IR, but there is no reason why new corridors like DFC/ HSC should not go for new technologies, as has been done by Sri. E. Shridharan in case of DMRC. Envisaged high speed corridors of IR should draw on new turnout technologies, breaking away from tradition, as mentioned in foregoing paragraphs. There is a need to build up further on this body of knowledge so as to make it further useful. Further, any technology, howsoever advanced, will require to be maintained. Our experience in maintaining existing turnouts on IR, as mentioned above, should be used to create a roadmap for devising maintenance technologies as well for such modern layouts for DFC/ high speed corridors. There is no reason why IR cannot be a torch bearer of technology instead of being a follower! ====================================================
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