Experimental investigation of influential factors on adhesion between wheel and rail under wet conditions

In high-speed railways, adhesion between wheel and rail is a very important function to maintain safety and stable operation from the standpoint of braking and driving, in particular under wet conditions at the wheel/rail interface. This paper describes an experimental investigation, which mainly focused on the effects of surface roughness and water temperature on the adhesion between wheel and rail under wet conditions. The experiments were conducted by means of a twin-disc rolling contact machine using different water temperatures and various surface roughnesses. The maximum traction coefficient obtained by the experiments, which is called adhesion coefficient in railways, increased with an increase of the water temperature or the surface roughness, and the roughness orientation had an effect on the maximum traction coefficient. Based upon the experimental results, it can be a considerable method to improve the adhesion coefficient between wheel and rail under wet conditions by raising the water temperature or increasing the standard deviation of roughness height or controlling the roughness orientation.