A rail is subjected to heavy stresses due to the following types of forces.
(a) Vertical loads consisting of dead loads, dynamic augment of loads including the effect of speed, the hammer blow effect, the inertia of reciprocating masses, etc.
(b) Lateral forces due to the movement of live loads, eccentric vertical loading, shunting of locomotives, etc.
(c) Longitudinal forces due to tractive effort and braking forces, thermal forces, etc.
(d) Contact stresses due to wheel and rail contact.
(e) Stresses due to surface defects such as flat spots on wheels, etc.