Torsional effect on track support structures of railway turnouts crossing impact

The introduction of special crossings and rail turnouts provides flexibility in the rail network as it allows for vehicles to switch between various tracks, therefore maximizing the utilisation of current infrastructure. Turnouts are a costly and critical feature to a rail system as they suffer adverse operational loads, in comparison to a straight rail track, and thus require regular maintenance. This leads to the question of whether a turnout can be justified for flexibility in comparison to upkeep costs throughout the life of the turnout. Therefore, great consideration is given to the interaction between the turnout components, and reducing wear in service, as failed components may have adverse effects on the performance of neighbouring components. This paper herein presents a development of 3D finite element (FE) model, fostering nonlinearities in materials’ behaviours, in order to analyse the forces and reactions within a railway turnout system. The analysis provide new findings of critical sections within the turnout and further enables alterations to be made to initial design of members in order to accommodate for the increased effects. The FE model comprises of standard concrete sleepers with 60 kg/m rail, and with a tangential turnout radius of 250 m. The turnout structure is supported by a ballast layer, which is represented by a deformable solid. The FE model is the world first to predict the torsional behaviour of the turnout and its fragile support by considering multi-wheel impacts which would simulate in-service and cyclic loading, and will be adapted as a set of concentrated loads to represent a coupled locomotive negotiating the turnout. The simulations demonstrate the significance of the third medium to suppress the torsional effect of the crossing forces on supporting bearers.