Rail Corrugation: Characteristics, Causes and Treatments

Corrugation is a phenomenon which has excited the interest of railwaymen for more than a century, but for which there often does not appear to be a cure. It has generally been realized that there are in fact different corrugation mechanisms, and that some types of corrugation can indeed be prevented. The present paper draws upon both the literature and the authors' experience to categorize corrugation according to two mechanisms: that damaging the rail (wear, plastic flow etc.) and that fixing the corrugation wavelength. Six types of corrugation are thus identified and described by the following proposed terminology: ‘heavy haul’, ‘light rail’, ‘ooted sleeper’, ‘contact fatigue’, ‘rutting’ and ‘roaring rails’. Both mechanisms are well understood for all but the last type of corrugation, for which a convincing and well-validated wavelength-fixing mechanism has yet to be demonstrated. Despite the absence of this understanding, satisfactory treatments of, and in many cases also means of preventing, all six types of corrugation have in fact been developed. Excitation of the vehicle's unsprung mass on the track stiffness is the most common wavelength-fixing mechanism.