Asymmetrical effects on railway turnout bearers due to wheelset impact over a crossing nose

Railway infrastructure is a nonlinear complex system as witnessed by its actual behaviors, geometry and alignment, wheel-rail contact and operational parameters such as tractive efforts. It generally experiences harsh dynamic load conditions due to train-track interactions. In addition, ballast pressure and its degradation will cause differential settlement, resulting in further aggravated impact forces acting on partial and unsupported tracks. Especially at switch and crossing areas, the aggressive dynamic train-turnout interaction often damages the supporting components such as turnout bearers and fastening systems. This study presents a nonlinear finite element model of a standard-gauge concrete bearer in a turnout system, taking into account the nonlinear tensionless nature of ballast support. The finite element model was verified using static and dynamic measures from in laboratory and in the field. In this paper, the dynamic effects of topologic asymmetry on both dynamic sagging and hogging behaviours of sleepers under a wheelset’s impulse loading are firstly highlighted. In addition, it is the first to demonstrate the dual-wheel effects of asymmetrical length on the nonlinear dynamic behaviour of the turnout bearers when the wheel running over the crossing nose. It would be naively thought that a failure of a single bearer or sleeper would not affect train operations; indeed, historical findings shows that such the failure at critical locations (e.g. at crossing panel, joints/welds, misaligned track, location with rail foot damage, and many more) could give rise to crossing nose damage, broken rail, broken joints, bowed baseplates, broken bolts, and so on. The outcome of this study is very critical to public safety and will improve the insight into structural damage and predictive condition-based track maintenance. It will help track engineers to appropriately adjust support profile and develop solution in order to mitigate excessive bearer/ballast interaction.