- Requirement of Proper Surveying for Constructing New Railway Line
For the construction of a new railway line between two places, proper surveying is essential. This surveying process involves various steps to determine the best alignment for the new railway line.
- Stages Involved in Proposing Suitable Alignment for New Railway Line
A number of stages are involved in proposing the most suitable alignment for the new railway line. These include examining the landforms and terrain, assessing the available resources and potential hazards, and analyzing the climate and land use. The surveyors must also consider the existing infrastructure and potential construction costs. All of these factors must be taken into consideration when proposing the best alignment for the new railway line.
Stages in Surveying for New Railway Line
Various steps involved in railway line surveying are as follows.
- Validation of New railway line construction
- Marking of tentative alignments
- Reconnaissance survey
- Selection of Good alignments
- Preliminary survey of alignment
- Final alignment survey
- Final survey report
Viability of New Railway Line Construction
Justifying the Viability of a New Railway Line
When a new railway line is proposed, the viability of the project must be evaluated. This involves taking into account several factors, such as the population living in the area, the economic conditions, the alignment and gradients, the presence of bridges, culverts, tunnels, etc., the presence of industries, agricultural, natural, and industrial resources, the presence of religious places, business centers, and markets, as well as the amount of revenue that can be generated from passengers and goods.
Analyzing the Population Habits and Living Standards
It is important to assess the population habits and living standards in the area covered by the proposed railway line. This helps to determine the potential revenue the railway line can generate.
Surveying the Topography
A topographical map of the area must be studied in order to determine the number of bridges, culverts, and tunnels that need to be built for the railway line. Additionally, a contour map of the area should be studied to assess the alignment and gradients.
Examining the Industrial and Agricultural Maps
Industrial and agricultural maps of the area must be studied to ensure that the new railway line will not encroach upon valuable agricultural land. The presence of agricultural, natural, and industrial resources should also be noted.
Studying the Presence of Religious Places, Markets, and Business Centers
The presence of religious places, markets, and business centers should also be noted when evaluating the viability of the new railway line. This helps to identify the potential sources of revenue for the project.
Calculating the Estimated Revenue
An estimate should be made of the amount of revenue that may be generated from passengers, goods, etc. This helps to determine the viability of the railway line and whether it is worth investing in.
Marking of Tentative Alignments
Shortest Possible Alignment
When constructing a new railway line, it is important to ensure that the alignment marked should be as short as possible. This will help to reduce the cost of construction as well as the amount of time it takes to complete the project.
Avoid High Value Areas
When marking the alignment of the new railway line, it is important to avoid passing through high value areas such as the center of villages or cities, valuable structures, etc. This will help to protect these areas and reduce the chances of any damage being caused by the construction of the railway line.
Minimize Curves
The alignment of the new railway line should also be as straight as possible and the number of curves should be minimized. This will not only help to reduce the cost of construction but also help to ensure a faster and smoother journey for those using the railway line.
Ridge Line Alignments
The alignment should also be marked on ridge lines whenever possible in order to reduce the amount of earth filling required. If it is necessary to mark across any valleys or depressions then proper attention should be paid to this area during the reconnaissance survey.
Avoid Religious Areas
The alignment should also avoid passing through any religious places, temples, churches, mosques, burial grounds, etc. This will help to ensure that the religious sensitivities of local communities are respected and that no damage is caused to these areas during the construction process.
Perpendicular River Crossings
Finally, when crossing any rivers the alignment should be perpendicular in order to reduce the amount of engineering involved in the construction process. This will not only help to reduce costs but also help to ensure that the new railway line is safe and secure.
Reconnaissance Survey
Reconnaissance Survey:
In the reconnaissance survey, data is collected from each alignment to determine which alignment is most suitable for construction. This involves measuring the magnetic bearings and distances of the lines of alignment with a prismatic compass, examining the surrounding area within 100 meter radius of the alignment, and noting the number of bridges, culverts, crossings, curves, depressions and high summits, and construction materials available.
Soil Survey:
A soil survey is conducted along the alignment to determine the soil type and the presence of water table level. This helps to identify potential construction difficulties and identify suitable materials for construction.
Index Map:
An index map is created for each alignment, noting the number of curves, bridges, approximate longitudinal section, and other details. This helps to easily compare and select the best alignment for construction.
Compensation to Private Property Owners:
If the alignment passes through private property, structure, or land, the details of the owner are recorded and the owner is compensated by the government. This ensures that private property owners are not unfairly affected by the construction.
Selection of Good Alignments
- Criteria for Selecting a Good Alignment:
When reconnaissance survey is completed for all the marked tentative alignments, the selection of a good alignment is based on various criteria. A good alignment should be short and economical, generate considerable revenue, have a minimum number of bridges and culverts, require minimal earth filling and excavation, and should not include vertical curves. Additionally, the construction material and labor availability should be taken into account, as well as the alignment connecting important and rush areas in the region, and the location of the station yards being easily reachable for passengers. Lastly, the cost of construction and expected revenue should be estimated along the good alignment. - Benefits of a Good Alignment:
When selecting a good alignment, there are several benefits to consider. A good alignment can help reduce the cost of construction and generate a considerable amount of revenue. It also helps to reduce the number of bridges and culverts, as well as the amount of earth filling or excavation needed. The construction material and labor availability will be closer, and the alignment will connect all the important and rush areas in the region. Furthermore, the station yards will be easily reachable for passengers. - Factors to Consider for Good Alignment:
When selecting a good alignment, several factors should be taken into account. Firstly, the length of the alignment should be short and economical. Secondly, the number of bridges or culverts should be minimized and the amount of earth filling or excavation should be reduced. Additionally, vertical curves should be eliminated and the construction material and labor availability should be as near as possible. Finally, the alignment should connect all the important and rush areas in the region, and the location of the station yards should be easily reachable for passengers.
Preliminary Survey of Alignment
Step One: Conduct a Preliminary Survey
Conducting a preliminary survey is the first step in selecting a good alignment. This survey consists of constructing a pillar at the starting point of alignment and connecting it to a nearby GTS benchmark using fly leveling. Additionally, longitudinal leveling with an interval of 20 or 40 meters is carried out along the alignment, as well as cross leveling with an interval of 100 meters. Magnetic bearings of each line of traverse are also noted in a level book.
Step Two: Prepare Route Survey Maps
A route survey map should be prepared to provide details of the 100 meters of land on both sides of the alignment. This can be done by plane table surveying or prismatic compass surveying. Additionally, permanent bench marks should be established at regular intervals, such as every 2 kilometers.
Step Three: Record Bearings and Soil Capacities
The bearing capacity of soil and the water table level should be recorded. Additionally, a map should be prepared for the marked station yards using plane table surveying.
Step Four: Check River Crossings
At river crossings, details such as the cross section, width, water level, HFL, and scour depth should be noted for a distance up to 1000 meters on either side of the crossing, with an interval of 100 meters. Boring the river bed is also necessary to determine the depth of the foundation required.
Step Five: Create Drawings and Estimate Sheets
Using all of the previously recorded readings, a drawing should be prepared for the entire alignment. Additionally, an approximate estimate sheet should be prepared for each alignment. This should include information such as earthworks, compensations, and costs of culverts and bridge structures.
Final Survey Alignment
Final Alignment Selection:
The final alignment is chosen based on the economy of the track. After the preliminary survey is completed, all the good alignments are compared and the most economical one is chosen.
Final Location Survey:
Before the final alignment is approved, a final location survey is conducted. This process involves constructing masonry pillars along the center line of the selected alignment at an interval of 1000 m. The position of the pillars helps to define the width required for the railway track. Along these pillars, pegs are placed at an interval of 30 m. Station yards, level crossings, culverts, bridge provisions, intersection points, and tangent points of the curves are also marked. Finally, the compensation of properties is estimated and marked.
Final Survey Report
Final Survey Alignment Report
When final survey alignment is completed, a comprehensive report is prepared and submitted for approval. This report details the project introduction, necessity, justification of the final alignment, estimation and specifications, expected revenue, and recommendations. The report also includes a set of maps with a suitable scale to give a better visual understanding of the project.
Project Introduction
The report includes an introduction to the project, outlining the purpose, scope and objectives of the project.
Necessity of the Project
The report outlines the necessity of the project and why the final alignment is justified.
Justification of Final Alignment
The justification for the final alignment is outlined in the report, including the length, area, number of bridges, culverts, and other crossings.
Estimation Sheet
An estimation sheet is included in the report which outlines the cost associated with the project.
Specification Details
The report includes specification details of the project, such as the materials used and the design of the project.
Expected Revenue
The report outlines the expected revenue from the project.
Recommendation of Project
The report includes an overall recommendation of the project.
Maps Included
In addition to the report, the following maps are included for a better visual understanding of the project:
Map of the Area Through Which Alignment Will Pass
Route Survey Map
Longitudinal Section of Alignment
Cross Section of Alignment
Map of Station Yards
Drawings of Culverts, Bridges, Tunnels, etc. to be Constructed Along the Alignment
Drawings of Station Buildings, Yards, etc.