Addressing the effects of overtopping vegetation on the performance of highway noise barriers

Clair W. Wakefield

Abstract


The effects of sound scattering by overtopping vegetation on the performance of highway noise barrier performance and the ways in which they might be addressed, either physically or administratively, was studied. The study also explored the interaction between pavement design and vegetation scattering effects. The scattering effects of scale model broad trees, placed to one side of, and then directly above a noise barrier, were also measured in a 1:20 scale model facility using an electric spark discharge as the sound source. The noise spectrum measured beside Highway 19 in Nanaimo, B.C. was used, which featured standard asphalt pavement and carried roughly 2,500 vehicles per hour at an average speed of vehicle of 75 kmph. The results showed that the traffic noise generated with OGA pavement contains less energy at middle and high frequencies, and these model results have been used to estimate the potential effects of overtopping vegetation on highway noise barriers.

Keywords


Acoustic noise measurement; Electric discharges; Electric sparks; Highway systems; Noise pollution; Pavements; Roads and streets; Scattering; Vegetation; Average speed; High frequencies; Highway noise; Model results; Noise barriers; Noise spectrum; Pavement designs; Potential effects; Scale models; Scattering effects; Sound scatterings; Sound sources; Spark discharges; Traffic noise; Vegetation scatterings

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