Numerical evaluation of rail track noise and vibration and components optimization

In the context of a project commissioned by the Swiss Federal Office for the Environment, an open-source modelling toolbox was developed to simulate and analyze rail tracks dynamics. In particular, a vibro-acoustic multi-sleeper model, which is based on advanced finite element modelling techniques, was used to investigate the effects of components properties on track noise and vibration. Considering changes around a reference construction (60E2 rail, SBB hard pad, B91 sleeper), parametric studies were performed on the dominant parameters identified for the acoustic and ballast protection performance indicators defined. The following sweet spot for the component properties of the track have been identified as using a rail pad of medium stiffness (1000 kN/mm at 1kHz, 300 kN/mm static stiffness) and high damping (at least 0.5) combined with soft Under Sleeper Pads (250 kN/mm). Based on the present models, such combination could provide both a significant noise reduction and a marked improvement in ballast protection compared to current track construction.