“Rutting” occurs mainly on the low rail in curves. It results from excitation of a flexural resonance of a wheelset, excited by high lateral tangential forces. Wear is very periodic and often occurs rapidly. Rutting is exacerbated by applied traction and by high angles of attack of bogies.
In existing track rutting can be reduced
- by reducing cant, thereby reducing the tangential force required for bogies to steer;
- by reprofiling to help steering;
- by controlling friction at the wheel/rail interface to reduce conditions for stick/slip.
Since rutting is a so-called “self-excited oscillation”, longitudinal irregularities are triggers but are not fundamentally important.