Safety assessment of underground vehicles passing over highly resilient straight track in the presence of a broken rail

Abstract

The current article presents the results of a research study that dealt with the simulation of vehicle—track interaction for a new slab track design, conceived to reduce noise and vibration levels transmitted to the neighbouring buildings. This design is mainly distinguished by its high elasticity and damping. A more elastic track, however, leads to greater rail deflections, which could affect the train's overall running safety. In this study, the derailment risk for trains running on slab track when encountering a broken rail has been evaluated. Two different types of rail fastening system with different elasticities have been analysed and compared. The results of this study will be considered in future track work projects. Up to now, the study has only been applied to straight track, even though the model is currently being extended to also study curved tracks. Numerical methods were used in order to simulate the dynamic behaviour of the train—track interaction. For that purpose, multi-body system (MBS) modelling techniques were combined with the techniques based on the finite-element method (FEM). MBS modelling was used for modelling the vehicle and FEM for simulating the elastic track. The simulation model was validated by comparing simulated results with experimental data obtained in field testing. During the simulations, various safety indices, characteristic of derailment risk, were analysed. The simulations realized at the maximum running velocity of 110 km/h showed a similar behaviour for several track types. When reducing the running speed, the safety indices worsened for both cases. Although the worst behaviour was observed for the track with a greater elasticity, in none of the simulations did a derailment occur when running over the broken rail.