A railway project implementation involves different stages, as follows:
Railway Survey for Justification of Constructing New Line
When the question of constructing a new railway line due to public demand or some other reason, demands an intensive study as regards the viability of the project.
Railway Survey for New Railway Line
To construct anything haphazardly is not engineering. Prior to the survey, we ensure a thorough study of the available maps of the proposed area. This helps in fixing suitable alignment facilitate various surveys work. The previous engineering surveys we follow first so that can broadly help for a new railway line.
Reconnaissance for Railway Survey
Along with the tentative alignments. We conduct the survey to collect the following data:
- The magnetic bearings of the lines of the alignment. We measure by prismatic compass. And the distances we measure by pacing (i.e. stepping) and note down in a field book.
- Approximate positions of different objects and the nature of the ground. Therefore, we can calculate the strip of land covering above 100 m on both sides of the alignment,
- We conduct a soil survey subsequently with the alignment of sides.
- Boring should be done along the alignment to know the nature of the water table.
- By the Abney level or hand level, we determine the slope or undulation of the ground.
- We note down the number of crossing points, like roads, rivers, canals, etc. We also record detailed information regarding these points so that it is possible to design suitable structures to cross them.
- Consciously we note down the number of curves and difficulties most importantly for curve setting.
Some Other Reconnaissance of this Survey
- With detailed information, we note down the number and position of culverts or bridges. Therefore, they can help us pertaining to span, HFL, discharge, etc.
- SBSC Team also collects the rainfall records of that area and the discharge records (for the past 10 years) of big rivers.
- Large depressions and high summits we try to avoid as far as possible so that we can minimize the cost of earthwork or tunneling. Where they are unavoidable, we keep a record of detailed information regarding these obstacles.
- Finding the availability of construction material and the possible route for their collection. As a result, we can minimize the construction cost and save time.
- Also, we collect data on the availability of labor, suitable places for labor colonies, etc.
- We prepare a project report accompanied by an index map of alignment, approximate longitudinal section, the number of curves, culverts, bridges, etc. to select a suitable alignment for a preliminary survey.
- SBSC Team prepares a preliminary record of properties for which compensation is to be paid along with such details as the name of the owner, quantity of land, present valuation, etc.
Importance of Reconnaissance for Railway Survey
By reconnaissance survey, we can find out a number of possible alternative routes between two points. This information becomes very useful at the stage in the selection of the best possible route between two points. The successful conduct of the reconnaissance survey entirely depends on the personal qualities and abilities of surveyors. They should have proper training and experience, the capacity of observation and interpretation of the territory, etc.
Instruments We Use in Reconnaissance for Railway Survey:
- Aneroid Barometer
- Prismatic Compass
- Binocular telescope
Preliminary Railway Survey
The objects of the preliminary survey are
- To conduct the survey work along the alternative routes (found out by reconnaissance survey) with the help of theodolite and leveling instruments.
- Determining the greater accuracy of the cost of the railway line along these alternative routes involving
- Cost of removing the obstruction, construction of bridges, etc.
- To decide the most economical and efficient route.
Importance of Preliminary Survey
The preliminary surveys decide the final route and recommend only one particular route in preference to other alternative routes. Thus, we conduct the preliminary survey with greater precision as the alignment of the final route depends on it.
Works of Preliminary Railway Survey
We mark out the x-sections of all representative points along the route and features. We take the cross-sections at 500ft intervals normally. Similarly, where the route crosses a river, we survey the river in detail for about one mile on either the upstream and downstream sides. We prepare the detailed maps and calculate the cost of different alternatives accurately to select the most economic routes.
The following points we should keep in mind while considering the justification of Constructing a new line
- The total population of the villages, towns, industrial places, etc. coming –under the project.
- Thorough studies of the standard of living and habits of the population, and the economic conditions of the locality. After all they will be a source of revenue for the department.
- The amount of agricultural, natural, and industrial resources.
- Information regarding religious places, religious fairs of festivals, business centers, etc.
- Estimation of the amount of revenue that may accrue from passengers, agricultural goods, industrial goods, natural resources, etc.
- Studies of the topographical maps to determine the number of culverts, bridges, level crossings, tunnels, etc.
- Also, we need to study an agricultural map so that we can avoid the affection of too much valuable land.
- We study a contour map in order to ensure economical alignment, avoiding unnecessary cutting or filling, and maintaining a permissible gradient.
- Moreover, we study an Industrial map to find the shortest route to connect industrial areas.
Reconnaissance for Railway Survey and Information Gathered
We generally gather information in the following two categories:
(01) Traffic Reconnaissance Survey.
(02) Engineering Reconnaissance Survey.
Traffic Reconnaissance Survey
This consists of a collection of information regarding the following:
1. General character of the country and the extent of cultivation.
2. Local industries and religious festivals.
3. The general conditions such as the prosperity of people in the locality and density of population and its distribution.
4. The probable amount of traffic to be served by a new railway line.
5. The probable new traffic lanes to be opened up to join large trade centers
6. Nature and volume of exports and their destination and origin.
7. The number of imports and centers of their distribution.
8. Possibilities of development of new industries and irrigation schemes as a result of new railway lines.
Engineering Reconnaissance for Railway Survey
In Engineering Reconnaissance Survey, We collect the following information:
1. Physical features of a country.
2. The surface formation of the ground.
3. Nature of soil.
4. Streams and rivers in the area especially those likely to be crossed by the track, their direction of flow, approximate width, and depth.
5. Positions of hills and lakes.
Marking of Tentative Alignment
After the decision to set up a new railway line, We mark the tentative alignments on the contour map and topographical map for the area.
While marking the tentative alignment, the following points should keep in mind:
- The route should be as short as possible.
- As far as possible, it should follow the ridgeline to avoid unnecessary earthwork in filling.
- It should cross rivers perpendicularly.
- Should not pass through religious places, such as temples, mosques, churches, etc. or burial grounds, burning Ghats, and so on.
- The route should not pass through the centers of villages, towns, valuable structures, etc. where the compensation payable is quite higher.
- It should not be too zigzag so that the number of curves is minimized.
- It should not cross large depressions or valleys, high summits, or ridgelines, to avoid huge earth fillings in areas of depression and tunneling in regions including summits.
- The tentative alignments of the two routes should mark to compare the costs of construction, feasibility, advantages, etc.
Location Survey is the final survey to locate the centerline of the railway line. The main object of this survey is to carry out a detailed 3d survey along the route. Which represents the most economical route from the data of the preliminary survey.
Importance of Location Survey
The location survey establishes the centerline of the actual track to be laid. And hence after completion of the location survey, the construction work starts.
Final Location Survey
On the basis of the preliminary survey, We select the most economical route. Before the approval of the project, we complete the final location survey in all respects. This survey helps the engineers in charge of construction projects.