Effect of lateral misalignment defects of rail joints on dynamic derailment behaviour in railway turnouts

This study aims to investigate the mechanism of wheel jumping derailment in the railway switch panel after a freight wagon passes over a rail joint defect (RJD) situated before the switch. For this purpose, a 3D vehicle-track (turnout) coupled dynamic model that considers the elastic deformation of the rails and wheelsets has been established. Several extreme running conditions, including sharp curves, low-speed railway turnouts, lateral misalignment defects of RJs, and empty wagons are all considered in the simulation model. The vertical wheel rise limit for the railway switch panel is presented for the evaluation of a quasi-static derailment risk. The wheel-rail impact behaviour and the evolution of the derailment processes in the switch panel are revealed, and the effects of wagon load and misalignment width of RJ sections on the vehicle's dynamic response and running safety are investigated. The results show that the root cause of the high derailment risk in the railway switch is a lower wheel rise limit at the front region of the switch rail when compared with the mainline. This dynamic derailment limit is sensitive to the car-body load and the misalignment width. Severe lateral defects of the RJ before the switch toe should therefore be avoided.