Various traffic calming schemes have been introduced by local authorities to slow traffic but the most effective usually involve some form of vertical deflection, normally in the form of a road hump or speed cushion. Although, vertical deflections are effective at reducing traffic speed there has been concern raised by some local authorities about disturbance to residents from vehicle noise and ground vibrations as well as discomfort to road users. The objective of this study was to compare the noise emission levels for a wide range of vehicles travelling over different designs of speed control cushions and humps; the vehicles included: a car, different types of buses and a range of commercial vehicles (gross weights 16t to 38t) which were chosen to demonstrate possible 'worst case' effects since these vehicles were known to be prone to generate above average levels of suspension related noise and body rattles etc when driven over uneven road surfaces. The results have been used to predict the change in traffic noise levels following the installation of such speed control measures for different proportions of buses and commercial goods vehicles in the traffic stream. Predicted changes in traffic noise levels were shown to be in good agreement with site measurements. (A)

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