Separation of Rolling Noise and Aerodynamic Noise by In-Service Measurement of Combined Roughness and Transfer Functions on a High Speed Slab Track

Abstract

Combined sound and vibration measurements during train pass-bys can be used to quantify contributions from the excitation and transmission of rolling noise. This is useful for the identification of sound sources and the assessment of the track contribution. In this paper, a practical application on a high-speed track is discussed. Acoustic measurements were conducted on a high-speed slab track, with pass-bys of the Thalys and conventional intercity trains, at speeds of around 300 and 160 km/h, respectively. Both sound pressure and vertical rail vibrations were recorded simultaneously. These were used to derive an estimate for the vertical track decay rates, combined effective roughness and transfer functions, with the Pass-by Analysis Software (PBA). The transfer function of the slab track is compared with a conventional concrete sleeper track, showing a distinct difference in the low and medium frequency ranges. The transfer function is characteristic of rolling noise, and if also measured at high speed, the contribution of aerodynamic noise can be quantified. For this train/track combination, aerodynamic sound sources are shown to contribute to the pass-by levels mainly in the lower frequency range. Based on the transfer functions and roughness levels, it is shown that rolling noise is still a significant noise source up to 300 km/h. © 2012 Springer.