Procedure and applications of combined wheel/rail roughness measurement

Wheel-rail roughness is known to be the main excitation source of railway rolling noise. Besides the already standardised method for direct roughness measurement, it is also possible to measure combined wheel-rail roughness from vertical railhead vibration during a train pass-by. This is a different quantity which has several applications. The measurement technique has significant practical benefits and has been in use for several years. There is currently still a need for measurement procedures for the following: - Assessment of noise control measures under operational conditions (rail and wheel dampers, roughness control, track/wheel geometry, railpads, shielding) - Separation techniques for track and vehicle contributions, and for separating rolling noise from other noise sources. Combined wheel/rail roughness and associated transfer functions offer an efficient means for this purpose. The method and procedures for the above applications are outlined here