Characterizing low-frequency structure-borne noise from multi-span bridges on high-speed railways

As high-speed railways become increasingly prevalent in urban areas and operating speeds continue to rise, the issue of bridge noise has become a critical concern, giving that bridge sections account for over 80% of high-speed railway noise. As train speeds continue to increase, the number of bridge spans included in a noise prediction model becomes a crucial factor in accurately predicting bridge noise. To address this issue, using a 32-m simply supported box girder, which is commonly used for high-speed trains, as an example, we conducted a comprehensive study using both the Fourier series method and the 3D boundary element method to investigate the impact of bridge span number on highspeed railway bridge noise. Our results indicate that the effect of bridge span number on bridge noise is highly dependent on the location of observation points with respect to the bridge and the distribution of bridge noise. Specifically, when beyond 54 m and part of the near-field area, a minimum of five bridge spans are necessary to obtain a more precise estimation of total bridge noise. This study aids to control bridge noise and can inform the implementation of noise reduction measures of varying lengths at different locations along the bridge.