Effect of vegetation on noise propagation in streets and squares

Abstract

This paper focuses on noise mitigation using vegetation in urban streets and squares of geometries typical for European city centres. Simulations of noise propagations have been performed using energybased CRR (combined ray-tracing and radiosity) and wave-based PSTD (pseudospectral time-domain) methods. The noise abetment schemes included the placement of vegetation on building facades and on low-profile barriers. Generally good agreement between the simulation methods has been achieved for the cases with vegetation on the facades, although for the cases with barriers the effect of diffraction at low frequencies shows the limitation of the CRR method. Considering a relatively high broadband absorption of 0.33 for facades as the reference cases, when vegetation is applied on all facades, a SPL decrease of up to 0.7dB and of up to 1dB can be achieved in the street and square, respectively. The insertion of a low-profile barrier in the street and the square can result in a decrease in SPL of up to 3dB and up to 4.5dB, respectively. Decreasing the absorption coefficient from 0.33 to 0.1 as the reference cases would result in an increase of broadband insertion loss by 2dB in the street and by 2.5dB in the square with vegetated facades.