Prediction of Low Frequency Noise Radiated from Vibrating Highway Bridges

Low frequency noise radiated from highway bridges due to fast moving heavy vehicles, is giving rise to a new traffic problem. In order to solve this problem, it is necessary to consider the reduction of noise and control of bridge vibrations. In this research, measurements of low frequency noise radiated from highway bridges and measurements of bridge vibration were carried out. From these results, the radiation efficiency of the slabs of the highway bridges was determined. Four types of bridge were measured, steel composite girder bridges, steel plate girder bridges, steel truss bridges and PC-girder (T) bridges. From experimental formulae for the radiation efficiency, and from vibration acceleration levels, the sound pressure levels and 1/3 octave band spectra of the low frequency noise radiated from the slabs were predicted. As a result, the sound pressure level at an arbitrary point can be predicted by measuring the vibration acceleration level of the bridge. Predictive calculation results agreed relatively well with measured values, particularly at locations close to the bridges.