Pressure Waves Generated When a Train Passes a Nearby Structure

When a high-speed train enters or leaves a tunnel, impulsive pressure waves are radiated from the entrance/exit portal toward the outside of the tunnel. The waves are called a “micro-pressure wave, ” a “tunnel entry wave” and a “tunnel exit wave.” A similar phenomenon occurs when a train passes a short structure in axial length in an open section (such as an over-bridge). We call it a “structure-passing wave.” The length of the structure along the railway is several times or less the diameter of the structure cross-section. Although the structure-passing wave is weak at present, it could cause an environmental noise problem of a low-frequency (which has become public concern) as the train speed increases. This paper describes the characteristics of the structure-passing wave based on the results of model experiments and acoustic analyses. The results obtained from the acoustic analyses were in good agreement with the result of the experiment except for the very short length structures. This implies that the structure-passing wave can be modeled on a superposition of the pressure waves radiating from both sides of the structure.