Differential Ballast Settlement, and Consequent Undulations in Track, Caused by Vehicle-Track Interaction

SUMMARY Dynamic vehicle/track forces from a train travelling over a long continuous wave in vertical track profile can compress the ballast preferentially in the troughs, thus making the wave worse. This model, built from simple representations of ballast, track and vehicle response, provides qualitative insights into the physical phenomena involved. Predictions are in accordance with expectations from practical experience, and numerical results are within the practical range. The simplifications at present incorporated in the model to offer these qualitative insights are not essential to it, and the approach can be extended to a full quantitative analysis.