Acoustic Monitoring of Rail-Head Roughness for Targeted Grinding and Noise Modelling

Railway rolling noise is a function of the combined roughness at the interface between the wheel and the rail. If wheels are comparatively smooth, the combined roughness is dominated by the rail-head roughness. It is therefore possible to monitor the level of rail-head roughness, and especially short-wavelength corrugation, by measuring the rolling noise with a microphone mounted on the underside of a rail vehicle in the vicinity of the bogie. This paper describes the principle behind this approach, and explains how it may be applied practically to identify roughness "hot-spots" so that grinding may be targeted cost-effectively. It also shows how the data thus acquired may be used to improve the accuracy of rolling noise models, which are of particular relevance at present due to the requirements of the "environmental noise directive"