Assessment of an Iterative Settlement Procedure in Railway Switches and Crossings Using Two Different Approaches

Differential settlement in transition zones of railways tracks is a consequence of variable track stiffness and load distribution potentially leading to the development of voided sleepers. This paper addresses the simulation of differential settlement in transition zones of turnouts. An iterative settlement procedure (ISP) has recently been proposed which combines short-term simulations of the vehicle-track interaction with long-term assessments of the settlement. A finite element model is used in order to estimate the track sublayers stresses. Owing to the asymmetry of turnouts, this ISP is extended in order to consider non-symmetry. The symmetrical and non-symmetrical approaches are compared in the case study of the Shift2Rail demonstrator located near Vienna, Austria. The transition zone between the plain line and the switch panel is considered where a good calibration of the short-term model is obtained. Further works should study the influence of flexible sleepers, the level of discretization and the dynamic contribution of substructure stresses. The novel non-symmetrical approach should prove even more relevant in the transition zone between long and short bearers in the crossing panel. Long-term monitoring tests on the track settlement are recommended to verify the accuracy of the proposed settlement prediction model. It is hoped that the novel approach can be used to help design and/or validate innovative concepts of turnouts and their effects on train dynamics.