Rails are similar to steel girders. These are provided to perform the following functions in a track.
(a) Rails provide a continuous and level surface for the movement of trains.
(b) Rails provide a pathway which is smooth and has very little friction. The friction between the steel wheel and the steel rail is about one-fifth of the friction between the pneumatic tyre and a metalled road.
(c) Rails serve as a lateral guide for the wheels.
(d) Rails bear the stresses developed due to vertical loads transmitted to them through axles and wheels of rolling stock as well as due to braking and thermal forces.
(e) Rails carry out the function of transmitting the load to a large area of the formation through sleepers and the ballast.