Study on Power-level Measuring Method of Structure-Borne Noise of Viaduct Road

Noise is generated when vehicles running on the viaduct road cause the structure to vibrate. The authors studied a measuring method for the power levels of structure-borne noise of viaducts, generated when tyres of running vehicles excite the road surface. This paper reports on the findings of the study on the effects of diffracted noise and measuring positions on the measured power levels. On the effect of diffracted noise, as a result comparing the structure-born noise measured at a point on the boundary of the road bridge site with a value gained by subtracting the diffracted vehicle noise from the measured noise, it was confirmed that the effect of diffracted noise is sufficiently low. As for the influence of measuring positions, when comparing values measured at a position located 1.2 m above ground with those at 0 m, a difference of about 3 dB was found. Considering the fact direct waves and ground reflected waves synthesize, it was confirmed that the difference is valid. As this study shows, influences of diffracted waves and measuring positions are small, and based on these results, the practical measuring method is proposed.