Study on the derailment of the remote locomotive in a heavy-haul train with distributed power at the turnout frog area: field investigation and numerical simulation

The derailment of railway vehicles in the turnout area is a worldwide concerned issue. Previous studies mainly concentrate on the derailment at the switch area, and the risk at the frog area is seldom concerned. Based on a specific derailment case of the remote locomotive in a 20,000-tonne heavy-haul train, a study on the derailment of the locomotive at the turnout frog area is presented. The conditions of the derailed locomotive and turnout track are introduced, and the potential influence factors are screened according to the field investigation results. A detailed simulation model that considers the complex wheel-frog/guard rail contact relationship and the interaction between adjacent vehicles is established. Through numerical simulation, the derailment process of the locomotive at the turnout frog area is reproduced, and the derailment mechanism is revealed, followed by the influence analysis of the potential factors. The results indicate that the combined effect of the compressive coupler force and the coupler jack-knifing promotes the derailment remarkably. Moreover, the derailment at the turnout frog area is more likely to occur under low-speed conditions, and the possibility of derailment can be reduced by decreasing the compressive coupler force and the friction coefficients between the wheel and stock/frog/guard rail.