Once a decision has been taken for a particular railway line to be constructed, a final location survey is done. The instruments used are generally the same as in the case of the preliminary survey. Final location survey is done to prepare working details and make accurate cost estimates in certain cases. The principal differences between the preliminary survey and the final survey are as follows.
(a) In the final location survey, the alignment is fully staked with the help of a theodolite, whereas it is not obligatory to do so in the case of preliminary survey.
(b) In the final location survey, a more detailed project report is prepared and submitted.
(c) All working drawings are prepared in the final location survey.
The following tasks are carried out in the final location survey.
(a) The centre line is fully marked by pegs at 20 m. At each 100 m, a large peg should be used.
(b) Masonry pillars are built at tangent points of curves and along the centre line at intervals of 500 m.
(c) Longitudinal and cross levelling is done to ascertain the final gradient of the alignment. All gradients are compensated for curves.
(d) The sites for station yards are fully demarcated.
In the final location survey, the following set of drawings is prepared.
(a) General map of the country traversed by the project at a scale of about 20 km to 1 cm
(b) Index map, scale about 2.5 km to 1 cm
(c) Index plan and sections
(d) Detailed plans and sections
(e) Plans and cross section
(f) Plans of station yards
(g) Detailed drawings of structures
(h) Plans of junction arrangements
The following broad objectives should be kept in mind when selecting the best possible alignment in the final location survey.
(a) Correct obligatory points
(b) Easy grades and flat curves
(c) Minimum cost of construction
(d) Minimum adverse effect on environment
(e) Ease of construction
(f) Potential for high speeds
(g) Avoidance of constraints for future expansion
(h) Minimum maintenance cost
A final project report is prepared based on the final location survey. The report consists of the following.
In this segment of the report, the following details are covered.
(i) Object of investigation and background
(ii) Programme and methodology of investigation
(iii) Special features of investigation
Characteristics of the Project Areas
In this segment the topographical outline of the areas and geographical features of the country are given to the extent to which these are likely to affect the alignment, probable stability of the line, cost of construction, working expenses, or future prospects of the proposed line. Climatic and rainfall characteristics and environmental characteristics such as the presence of corrosive factors, pollution, etc., which may have an effect on the design and maintenance of structures and bridges, are also brought out.
Standard of Construction
This segment gives details of the following.
Gauge The gauge adopted for the proposed line and the reasons, if any, for adopting it.
Category of line The category of the line, the maximum speed potential of the line, the maximum axle load, the loading standard of bridges, and the basis for adopting the same.
Ruling gradient The gradient adopted and the basis for its selection.
Curves The sharpest degree of curvature adopted, the basis for its adoption, and its impact on the projected speed compatible to the category of line.
Permanent way The rail section adopted, the decision as to whether welding of the rails will be carried out or not, and the type and density of sleepers provided in the project estimate.
Ballast The type and depth of ballast cushion provided.
Stations Spacing of stations in the case of new lines, provision for future intermediate stations, and the scale of facilities contemplated at stations.
Signalling and telecommunication The standard of signalling adopted and the scale of communication facilities provided.
Traction The type of traction proposed.
Other details Road crossings, station machinery, residential accommodation, service and maintenance facilities, etc.
This segment provides relevant information and data related to the various alternative routes examined and gives an insight into the factors influencing the choice of the route adopted for the project.
This section furnishes information and data for the project manager to enable him to understand the scope and extent of the project and to assist him in formulating the strategy for the execution and management of the project. It must focus on the problems likely to be encountered, identify the areas requiring special attention, and place the knowledge and information gathered at the investigation stage for evolving optimal solutions.
Estimation of Cost and Construction Schedule
This segment gives a cost estimate of preliminary expenses, land, formation, bridges, permanent way, station building and residential quarters, road crossings, station equipment, signalling and interlocking, rolling stock, etc. The schedule of' construction as well as investment is also given. A network should be developed for projects costing above Rs 5 million.
This section details the organizational structure for the execution of the project, the proposed headquarters of the project manager and other construction officers, as well as the allocation of the various construction activities. Health and hygenic conditions provided to the staff as well as the provision of necessary medical
establishments may be indicated, along with suggested plans providing for the housing of staff and labour and the construction of temporary office buildings. Comments regarding the availability of water for construction purposes and its suitability for drinking purposes may also be given. The purpose and final cost allocation of such plans may also be indicated.
The report is accompanied by tabulated details of curve abstract, gradient abstract, bridge abstract, important bridges, stations, machinery, stations, and station sites.
Arrangement of Documents in the Report
All the documents pertaining to a final location survey report should be in the following order.
1. Covering note
4. A list of drawings accompanying the report
5. Appendices to the report
(a) Historical and geographical aspects
(b) Location report
(c) Rates for construction work