Efficiency of resilient wheels on the alleviation of railway ground vibrations

The aim of this paper is to show how resilient wheels, initially used for reducing the noise generated at the wheel/rail contact and stresses on wheels, are also efficient for reducing ground vibrations. Brussels tramway T2000 is considered as an example. A prediction model as complete as possible is used, taking into account the track and the vehicle dynamics. A multibody approach is chosen to describe the vehicle behaviour, over a finite element model for the track. The soil is modelled with the finite/infinite element approach, taking into account the layered configuration of the ground. Three variants of tram are analysed, focusing on the resilient wheel stiffness. The stiffness and damping properties of the wheels are obtained by updating a finite element model. A validation step is presented, based on measurements at the soil surface during the passing of the tram over a rough rail and a local rail defect. A modal decomposition is applied on the vehicle model with emphasis on relevant modal contributions in the wheel/rail forces. A sensitivity analysis of the resilient wheels stiffness is performed, showing a meaningful decrease of ground vibrations using a soft resilient material. This study shows that the vehicle dynamics intervenes in the onset of the vibration waves in the soil and demonstrates the real interest of a compound vehicle/track/soil model in the design of this kind of wheel.