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ADVANCE ENGINEERING SURVEYING (3+1) Lecture 8: Route Surveying Dr. Mohsin Siddique Asst. Prof. Dept. of Civil Engineering FAST-NU 09/10/2012
Route Surveying
• Route surveying is a branch of surveying which includes all fieldworks and requisite calculations together with maps, profiles and other drawing that involved in the planning and construction of any route of transportations. • Route surveying is a branch of surveying comprising all survey operations, required for design and construction of engineering works such as highways, railroads, pipelines or canals. • Route surveying can be applied in surveys which require establishing the horizontal and vertical alignment (also known as gradeline) for transportation facilities. Alignment refers to the shape or geometry of any transportation route. • Route surveying includes field and office work required to plan, design and layout any “long and narrow” transportation facility.
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Route Surveying
Side-hill section
Route Surveying
• In general, route surveys consist of: ▫ determining ground configuration and the location of objects within and along a proposed route ▫ establishing the alignment of the route ▫ determining volumes of earthwork required for construction • It is important in route selection that the chosen route must satisfy all design requirements with minimal social, environmental and financial management. • Route surveys are commonly used for levees, stream channels, highways, railways, canals, power transmission lines, pipelines and other utilities.
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Route Surveying
• Functions of the survey engineer ▫ Obtain necessary information regarding terrain and land use ▫ Make surveys to determine detailed topography ▫ Establish horizontal and vertical control required for construction layout • Three Basic Surveys in Route Surveying ▫ 1. Reconnaissance ▫ 2. Preliminary Survey ▫ 3. Location Survey
Three Basic Surveys in Route Surveying
1. Reconnaissance • Reconnaissance is a rapid survey, or rather a critical examination of an area without the use of ordinary surveying instruments. • Certain instrument may be used for approximating the rate of maximum grade for the roadway. • The first step in this type of survey is to obtain and use large scale maps and aerial photos, if available. If there are no available maps then topographic survey can be done. • These maps are used by the engineer as a guide in the selection of alternative routes. Map scales range from 1 in = 2000 ft (1:24000) to 1 in = 200 ft (1:2400).
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Three Basic Surveys in Route Surveying
1. Reconnaissance • There are two features of topography considered in reconnaissance. These are: • a. Ridge Line also known as watershed line is the line or surface along the top of a ridge. A ridge is a long narrow chain of hills of mountains. • b. Valley Line also known as watercourse line is a line or surface between mountains.
Three Basic Surveys in Route Surveying 1. Reconnaissance • The purposes of reconnaissance include: ▫ Find whether there is any satisfactory line between the proposed routes ▫ Establish the best line ▫ Determine approximately the maximum grade to be used ▫ Report the type of geological formation and the cost of construction ▫ Take note of the existing resources of the area, its manufacturers, mines, agricultural or natural products and the capabilities of improvement and development of the area resulting from the introduction of the roadway
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Three Basic Surveys in Route Surveying 2. Preliminary Survey • Preliminary Survey is based upon the results of the reconnaissance. • This survey may be conducted on the ground with surveying instruments, or in the office, using aerial photogrammetry. • Modern transportation routes are usually located using low-altitude photogrammetric maps at a scale of 1 in = 50 ft (1:600) and 2 ft (0.5 m) contours. • The state of the art of modern photogrammetry and computer applications is such that even the required earthwork (cut and fill) computations for roadway design can be done using the data from aerial photography.
Three Basic Surveys in Route Surveying 2. Preliminary Survey • The basic product of the preliminary survey is the location of a baseline or connecting traverse. • This is a series of straight lines that run along or near what will be the centerline of the final route. • It is essentially the horizontal alignment of the route, without the curves. • Distances along the traverse are marked as stations & pluses and run continuously from the beginning points of the route. • The angles at intersection points where the baseline tangents change direction are carefully measured. • Data for drawing a profile of the traverse line are also obtained.
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Three Basic Surveys in Route Surveying 2. Preliminary Survey • Preliminary survey serves the following purposes: ▫ Fix accurately the maximum grade for use in Location survey ▫ Determine the best line ▫ Provide a map as basis ▫ Make a close estimate of the cost of work ▫ Secure, in certain cases, legal rights by filing plans
Three Basic Surveys in Route Surveying 3. Location Survey • Location Survey is the final fitting of the line to the ground. • In Location, curves are used to connect the straight lines or “tangents” and the alignment of the route. • The horizontal alignment of the route can be laid out on the ground after the curve computations have been made and appropriate field notes prepared. • Location survey includes setting stakes along the tangents and the curves of the route centerline . • Since the stations and pluses of the final centerline run along the curves as well as the tangents, new stations have to be computed for points on the final alignment.
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Three Basic Surveys in Route Surveying 3. Location Survey • As the staking of the centerline progresses, topographic data are collected, and property corners within the route boundaries or rightof-way (ROW) are located. • Profile and cross-section data are obtained for final design, for preparation of engineering drawings, and for final estimates of earthwork quantities. • The final grade line (vertical alignment) is established so as to balance cut-and-fill (excavation and embankment) quantities. • On the engineering drawings the final horizontal alignment is shown in plan view, above the profile view of the vertical alignment.
Three Basic Surveys in Route Surveying 3. Location Survey • The plan view should include the bearings of the tangents, angles of intersection, stationing, and geometric data for each horizontal curve. • It also should include topographic data within and adjacent to the ROW lines, and any existing structures affected by the project. • The profile view should include the existing ground surface, proposed route grade line, grades (slopes) of all the tangent sections, vertical curve data, and other pertinent information.
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Horizontal Alignment
Vertical Alignment
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