Effect of roadside vegetation on the reduction of traffic noise levels

Abstract

A study was carried out to determine the effect of roadside vegetation on the reduction of road traffic noise levels under varying traffic conditions. Roadside vegetation which have the potential to act as noise barriers were selected for this study. The road traffic noise was measured together with the parameters that control the vegetation. Several noise level descriptors were recorded together with the A-weighted continuous noise level. The results show that higher frequency noise (above 4 kHz) is heavily attenuated by the vegetation barriers with virtually no attenuation for low frequency noise (below 100 Hz). The width of the vegetation barrier is linearly proportional to the amount of sound absorption. Without the vegetation barrier, the observed maximum and minimum noise levels were 72 dB(A) and 64 dB(A) respectively. On average, vegetation barriers were able to reduce the noise by 4 dB(A) which corresponds to an approximately 40% acoustic energy reduction. Thus, with careful planning and growing of roadside vegetation, the effect of road noise can be reduced.