High railway rolling noise reduction by combining existing track based solutions

Abstract

The overall objective of the EU funded Quiet-Track project is to provide step changing track based noise mitigation systems and maintenance schemes for the railway rolling noise. This paper focuses on the combination of existing track based solutions to yield a global performance of at least 6 dB(A). The analysis and validation was carried out considering a track section in the network of Attiko Metro line 1 with an existing outside concrete slab track (RHEDA track) where high airborne rolling noise was observed. The procedure for the selection of mitigation measures is based on numerical simulations, combining two software tools for noise prediction, WRNOISE and IMMI with experimental determination of the required track and vehicle parameters. The availability of a detailed rolling noise calculation procedure, which includes the modelling of the wheel/rail source intensity and of the noise propagation with ability to evaluate the effect of modifications at source level (e.g. grinding, rail dampers, wheel dampers, change in resiliency of wheels and/or rail fixation) and of modifications in the propagation path (absorption at the track base, noise barriers, screening) allows for detailed designing of measures and of ranking individual measures. A relevant combination of existing solutions was selected in function of the simulation results. Three distinct existing solutions were designed in detail aiming at a high rolling noise attenuation and not affecting the normal operation of the metro system: - Action 1: implementation of sound absorbing precast elements (panel type) horizontally distributed in the track bed; - Action 2: Implementation of an absorbing noise barrier with a height of 1.10-1.20 m above rail level and close to the track and vehicle; - Action 3: Installation of rail dampers at the selected track. The selected solutions were implemented on-site and the global performance was measured-step by step-for comparison with simulations. A very good agreement was found between simulations and measurements after installation and a global noise attenuation performance of 9 dB(A) was obtained at the considered receiver location..