Steel rail is the main component of railway track. Its function is to guide the wheels of rolling stock to move forward, bear the huge pressure of the wheels, and transmit it to the sleepers. The rail must provide a continuous, smooth and least resistance rolling surface for the wheels. In the electrified railway or automatic block section, the rail can also be used as a track circuit.
The section shape of Steel Rails adopts the I-shaped section with the best bending resistance, which is composed of three parts: rail head, rail waist and rail bottom. In order to make the rail better withstand the forces from all aspects and ensure the necessary strength conditions, the rail should have sufficient height, its head and bottom should have sufficient area and height, and the waist and bottom should not be too thin.