Effects of source type, position, and train structure on BEM calculations

The 2D and 2.5D BEM can be used for calculating the sound field around structures with complex cross-sections. For railways, the calculation of the effects of noise barriers proves particularly challenging for a number of reasons such as the ballasted track, the modeling of the source and the modeling of the structure of the train. In this work, the focus lies on effects of the latter two for diffraction edges positioned close to the track. Such situations occur for example at railway platforms. Different source types, source positions, and train cross-sections were simulated using a 2.5D BEM approach and compared to measurements of train passbys near and far away from the track. Furthermore, simulations were performed and compared to measurements on the platform using a defined sound source located on the track. We will show that comparisons to the 2.5D BEM calculations are in good agreement with measurements from the point source. For passby measurements we will illustrate the difficulties to reconcile the measurements from positions on the platform and far away from it with the BEM simulations.