The gradient is the rate of rising or fall off the track. It is expressed as the ratio of vertical distance to horizontal distance or as the percentage of rising or fall. If any track rises 1 m 100 m horizontal length, its gradient is expressed as 1 m 100 or 1 percent. If another track falls by 1 m 50 m length, its gradient is 1 in 50 or 2 percent.
Gradients are provided to the formation of rail track to serve the following purpose:
- To reduce the cost of earthwork
- To provide uniform rate or fall as far as practicable.
- To reach the stations situated at different elevations.
- To drain off rainwater
- Factors which affect the selection of gradient are the following:
- Nature of the ground
- Safety required
- Drainage required
- Total height to be covered
- Hauling capacity of railway engines.