Scale modeling of railway noise barriers

Noise barriers are an efficient way of reducing the noise from railways, particularly the noise produced in the region of the rails and wheels. Several designs of noise barrier have been suggested in the literature which aim to improve the insertion loss over that obtainable from a plane screen of the same height. The positioning of these barriers is governed by the limitations imposed by the structure gauge of the railway. Scale modeling has been carried out in a humidity-controlled anechoic chamber at a scale of 1:20. Appropriate materials have been selected to model the impedance of the track ballast, absorbing barrier surfaces and grassland at the reduced scale. To model the interaction between the side of the train and the barrier realistically, models appropriate for a high-speed train cross section have been used. Experimental results for the insertion loss of shaped and multiple-edge barriers are compared with the results from numerical modeling. The efficiency of each of the designs is assessed. The generation of time histories for the passage of trains and the calculation of noise indices are considered.