Contribution of Various Single Median Barriers to Environmental Noise Pollution

Median barriers are used in state highways to prevent cross-median crashes. However, installation of median barriers as a noise source in urban areas could make an increase in sound inconvenience. The aim of this paper is to investigate the noise performances of median barriers having different shapes. The 2D dimensional boundary element method (BEM) is used to analyze the influence of the screens. Various median barriers are designed and results are presented demonstrating that the T-shape, A-shape, Y-shape and Z-shape barriers produce less noise pollution compared with a plain barrier as their A-weighted insertion loss in the source side is higher than that of a simple plain barrier. Comparisons between all tested screens indicate that the best efficiency of noise pollution reduction is found by tilted barriers compared with plain barrier by 1.2 to 1.6 dB (A) . It is also found that, such performance is higher when the source side of the barrier is tilted outward by 10 degrees.

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