Evaluation of Dynamic Derailment in a Railway Switch Considering the Longitudinal Impacts Caused by Vehicle Retarder

The operating conditions at the railway marshalling station are quite complicated, featuring low-speed turnouts, sharp curves, and vehicle retarders. Train derailments frequently occur in the switch panel. However, the passive safety and derailment behaviour considering the longitudinal impacts are still not clearly understood. With this aim in mind, a three-dimensional freight wagon-track (turnout) dynamic interaction model considering the impacts between wagons in longitudinal direction is established. The braking of the vehicle retarder on wheels is also simulated. The comparative analysis between the simulation results and field observation for the derailment is presented. The derailment limits along the switch are assessed based on 3D quasi-static analysis and numerical simulation. The results show that the longitudinal impact from the rear wagon can significantly increase the derailment risk when an empty wagon located in the middle passes through the vehicle retarder and switch. As the side wear depth of the switch rail increases to 5 mm, the vertical wheel rise at the front of the switch increases from 0 to 4.73 mm even though the other parameters keep an ideal level. Proper measures such as rail grinding and lubricating are suggested to be adopted for optimizing wheel-rail contact relationships and improving running safety.