Vibrations in signalling equipment: limitations and improvements of current standards

Signalling equipment mounted on rails are subjected to harsh environmental conditions in electrical, thermal and mechanical terms. The presence of nearby local features in the track (such as void sleepers, joints, local railhead defects, bad geometry welds) or highly defective passing-by wheel treads polygonization, wheel flats) give rise to exceptionally high mechanical stresses that are not properly accounted for in the current standards for signalling equipment acceptance. The paper describes the results of a measuring programme held in a location where wheel treadles suffer abnormal failures. A critical analysis of current standards is shown, together with the proposal of new indicators to better characterize the vibration environment that can be encountered in practice on a real track.