Scale and Numerical Modelling of a Metro Rail Viaduct with Sound Absorption to Reduce In-Car and Wayside Noise

A scale model of a 2-car metro train on a slab track rail viaduct was employed to investigate the reduction of in-car and wayside noise when acoustic treatments were added to the inside face of the edge noise barrier and within the four-foot. The performance of the acoustic treatments was evaluated in full octaves for the full-scale frequency range of 31.5 Hz to 2 kHz. The scale model results were compared with general rail noise modelling prediction formulae and with numerical modelling results using ODEON. The model results confirmed that the interior noise level experienced by passengers is likely to increase with the addition of viaduct edge noise barriers and that wayside noise levels are reduced due to the noise barrier effect. With the addition of acoustic panels on the inside face of the viaduct edge barrier and within the four-foot, in-car and wayside noise levels reduce.