Why not Rail Rail corrosion?
In fact, from the security perspective, the railway department also hope there is rust because of rust on the surface of the rail, said adhesion coefficient can be increased after EMU locomotive / when the possibility of greatly idling or gliding down, thus reducing the possibility of damage of wheel rail. Actually, when the rails were just being laid, they were all rusted.
The friction force of railway locomotives, EMUs can advance the power comes from between the wheel and rail forces, so as long as there is a certain volume of the railway line, the rail surfaces are smooth and no traces of rust.
As the train passes, the constant rail friction with the wheel rust away.
