Parameter Identification of Tram Acoustic Models for Noise Mapping from Pass-by Measurements
Résumé
From the beginning of 2019, the new European common method CNOSSOS-EU must be used for strategic noise mapping in accordance with Directive 2002/49/EC. For the assessment of railway noise emissions, the method requires a detailed description level. On the one hand, the contributions of the different sources (rolling, traction) must be specified. On the other hand, for rolling noise, excitation data (wheel/rail roughness) must be distinguished from the vibro-acoustic efficiency (track/vehicle transfer functions) as well as the relative contributions of track and vehicle. For conventional railways, national operators generally have a large amount of experimental data and models available to evaluate these input parameters. This is not the case for tramway networks, for which few studies or measurements exist, particularly with regard to wheel and rail roughness or track transfer functions. This study aims to identify the parameters required by CNOSSOS-EU based on pass-by and wheel/rail roughness measurements for several sites and vehicles on the Lyon tramway network. Near-field emission and propagation models are first developed and then, an inverse method is proposed for parameter identification. Several options are tested. The data obtained are compared with the default values of the CNOSSOS method for conventional rail.
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