Wheel Flats in the Dynamic Behavior of Ballasted and Slab Railway Tracks

Abstract

Wheel flats induce high-impact loads with relevance for the safety of the vehicle in operation as they can contribute to broken axles, hot axle boxes, and damaged rolling bearings and wheels. The high loads also induce damage in the track components such as rails and sleepers. Although this subject has been studied numerically and experimentally over the last few years, the wheel flat problem has focused on ballasted tracks, and there is a need to understand the phenomena also for slab tracks. In this research, a numerical approach was used to show the effects of the wheel flats with different geometric configurations on the dynamic behavior of a classical ballasted track and a continuous slab track. Several wheel flat geometries and different vehicle speeds were considered. The nonlinear Hertzian contact model was used because of the high dynamic variation of the interaction of the load between the vehicle and the rail. The results evidenced that, for the same traffic conditions, the dynamic force was higher on the slab track than on the ballasted one, contrary to the maximum vertical displacement, which was higher on the ballasted track due to the track differences regarding the stiffness and frequency response. The results are useful for railway managers who wish to monitor track deterioration under the regulatory limits.

Development and Validation of a Weigh-in-Motion Methodology for Railway Tracks

“…Since no significant variations in the dynamic wheel-rail contact load are expected to occur for the scenarios analysed in this work, a linearised stiffness approximation may be acceptable [31]. However, for other scenarios, such as the wheel flats, the nonlinear contact between the wheel and the rail should be adopted [6].…”

“…Train WIM is of great interest in controlling axles and vehicle loads, detecting wheel defects and predicting train derailment in order to guarantee acceptable train operations and safety [1][2][3][4][5]. The presence of high loads in the track induces damage in the track components, such as rails, sleepers and ballast, which has implications in maintenance periodicity [6]. WIM systems are essential for freight wagons with overloaded or unbalanced loads, as it leads to damages to the infrastructure on the one hand and enhances the risk of derailment on the other hand.…”

Detection of Wheel Polygonization Based on Wayside Monitoring and Artificial Intelligence

“…Although these components represent a high maintenance cost, serious accidents with high economic losses and possible human injuries can be avoided. Regarding railway safety, wheel defects are one of the main causes of accidents [ 10 , 11 ], causing interruptions in the normal operation of railway transport systems and considerably reducing their reliability. Furthermore, these defects promote negative effects on both the vehicle and track, increasing maintenance costs.…”

An Unsupervised Learning Approach for Wayside Train Wheel Flat Detection

“…Wheel flats are the most common type of defect in train wheels and remarkably affects running safety and causes significant damage to the infrastructure, namely the rails and sleepers, due to the higher impact forces induced in the track [ 6 ]. The initial cause for the wheel flat is the friction between the wheel and rail due to braking forces, as friction can change the shape of the exterior perimeter of the wheel from round to flat.…”