Prediction of rolling noise from ballast and slab track at speeds up to 360km/h

Abstract

The total noise generated during the passage of a high speed train results from different noise sources including traction and auxiliary systems, wheel/rail interaction (rolling noise) and, at high speeds, aerodynamic noise from the lower and upper regions of the train. This paper focuses on the contribution of rolling noise to the total noise. Slab track is conventionally considered to radiate more noise than ballast track. This paper presents the results of studies undertaken to better understand the performance of high speed slab track using parameters relevant to High Speed Two (HS2). The approach was validated with a comparison between predictions and measurement data from high-speed trains running on ballast track at speeds of up to 350km/h. The predictions indicate that slab track could result in rolling sound pressure levels of the order of about 1 dBA greater than for the ballast track. The similarity in noise emission is a result of the dual stage fastening system. The upper pad fitted above the base plate on the fastening has the effect of increasing the decay rates at higher frequencies compared with a notional slab track with a single layer soft fastener. This compensates for the increased radiation, particularly from the rail, due to the absence of ballast absorption. Considering the total noise, at speeds above 300 km/h the total noise including other sources is expected to be similar for ballast and slab track. At lower speeds, ballast track is expected to be somewhat quieter. This study identifies that the relative differences between slab and ballast tracks are highly dependent on the precise characteristics of the systems being compared.

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ORCID for David Thompson: orcid.org/0000-0002-7964-5906

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