Railway Electrification Basic | Surveying and Foundation Types

Railway electrification basic

Railway electrification is a wide and interesting field which is not taught in our BTech electrical.

So, there are some basics one needs to know if they got their first job in the railway electrification field.

The topic for the day is SURVEYING. 

Railway Electrification Survey

When you listen to railway electrification, your mind will get the visualization of cables, electricity, source of generation, the value of voltage, etc. 

So, let’s make your first visualization to picture. For laying cables one must need poles, for erecting poles one needs pits (foundation in railway terms), and for the foundation to take place one must need to survey the land.

There might be a foundation on bridges, under overhead lines (overhead lines vs underground lines) so to ensure proper marking Survey becomes the most important step.

Different types of foundations are given by the designer and there are certain rules to be followed while giving them, some of the terms used are-

• Cess level: Height from the highest rail level to the ground. 
• Shoulder width: Are we getting the area required for the foundation. 
• Soil pressure: If the soil is capable to hold the vertical and axial load created by the cantilever assembly. 
• Clear span: distance from the nearest pole to the adjacent pole. 

Note: clear span is generally in the multiple of 4.5m.

There are several types of foundation used in railway construction depending upon the soil bearing capacity, shoulder width, cess level broadly classified as…

1. Side bearing (or B-type) foundation
2. Side gravity (or Bg-type) foundation
3. Pure gravity (or P-type) foundation
4. New pure gravity (or Mg-type) foundation
5. WBC or NBC type foundation

In the next article, I would share in details about the statistical data for each type of foundation, terms values, and the ratio of cement: sand: concrete as well as quality checks done by the engineers for ensuring the fastest, economical, and safest travel to the passengers via rail.