Elevated noise sources in the European noise prediction model

The prediction model of the Environmental noise directive 2002/49/EC was transposed into Austrian national regulations in 2021 and 2022. In comparison to the Austrian prediction model defined in ONR 305011, which was last updated in 2009, it allows far more acoustic details to be taken into account enabling a more realistic description of noise emissions and propagation than before. For instance, an additional, elevated noise source position is used to model traction noise of aggregates or fans at the upper part of locomotives or motor coaches and aerodynamic noise caused by pantographs at high speeds. For free sound propagation the effect of split source positions is usually negligible, while in case of noise barriers the elevated source position lowers the insertion loss. This article discusses this effect using exemplary calculations with the European prediction model under various conditions (e.g. different barrier heights, and train speeds). The results emphasize the importance of accurate model input parameters describing traction and in case of high speeds aerodynamic noise for predictions, which need high accuracy.