Traffic noise attenuation by green belts

Green belts reduce the traffic noise at the same time transfigure environment. The traffic noise attenuation by green belts and the effects on different frequencies were studied by in-situ and outside investigation in this paper. The results indicate: green belts could reduce traffic noise, and its effect reduces when canopy density increased; There is a highly significant linear relationship between greening attenuation of noise and belt width, the correlation modulus is 0.990, however the noise attenuation rate decline when belt width increased; noise attenuation effect of different green belt type vary, the maximal attenuation effects by Robinia pseudoacacia is 15.38 dB, and the attenuation effect by Populous and Salix are weaker, respectively 7.25 dB and 11.02 dB; Attenuation in high-frequency is lower than the other frequencies.