Track data-oriented maintenance intervention limit determination for ballasted light rail tracks through multibody simulations

Abstract

Light rail trains (LRT) form an important part of public transport. However, due to the high life-cycle costs, light rail systems are not always considered a suitable solution. One way to reduce life cycle costs is in the area of maintenance management. The maintenance of light rail tracks is based on the experience of the infrastructure managers and focuses on preventive and corrective maintenance. The current track condition is not always sufficiently considered, which means there are hardly any possibilities for optimizing costs. In particular, tolerance and limit values for maintenance measures applicable to light rail systems have not yet been defined or adequately analyzed. Instead, limits are taken from the regular railway guidelines, which means that adequate intervals for maintenance and repair measures are not possible. Tolerances and limits for light rail systems should be based on vehicle reactions, which in turn depends on the current track quality. This would permanently lead to a track condition which allows an operation that is comfortable for the passenger or economically profitable for the infrastructure manager. The focus of this work is on the evaluation of the track geometry of LRT tracks, for which, based on the vehicle reaction, tolerance and limit values for maintenance measures are determined. Since data for sections in very bad condition were not available, artificially poor track conditions are generated by a successive increase of the signal amplitudes within the frequency range of the measured track geometries. The track measurement data is imported into a multi-body simulation software and the vehicle response is calculated on the passage of selected sections for a running time of five minutes. Then the vehicle reaction is evaluated on the basis of the passenger comfort, the track loading and the derailment coefficient, and the quality of the track position is determined. The load on the track body calculated by the multi-body simulation does not exceed permissible limits in comparison to the comfort value and the derailment coefficient. To better illustrate the tolerances and limits for light rail systems derived from the vehicle reaction, a track geometry index is introduced. The Track Geometry Index allows a track manager to visualize the deterioration of the track layout and to divide it into different quality levels. The quality levels help infrastructure managers to determine the time for repair measures in a scheduled manner. Two LRT lines are examined in detail using the method developed here. The result indicates that the routes considered in this work were repaired too early. Future work should detect irregularities in the road through continuously measured accelerations on the vehicle and in the track. In addition, acceleration data can then also be used for the assessment of longer sections of the route using the approach developed here.