Traffic calming measures are used to reduce speeds and consequently accidents. The original work on speed reducing road humps was carried out at TRL in the early 1970's and was based on circular profile (round top) road humps of various dimensions. More recently, in order to improve the advice to Local Highway Authorities in Great Britain, the Driver Information and the Traffic Management Division of the Department of the Environment, Transport and the Regions has commissioned TRL to assess the effectiveness of a wide range of physical traffic calming measures used on the public roads. The work has included measures involving vertical deflections (round-top humps, flat-top humps, thumps and lower height humps, speed cushions, sinusoidal humps and 'H' and 'S' humps) and horizontal deflections (single lane working and two way chicanes). This paper summarises the results that have been obtained by TRL from a number of different test track trials and public road studies of urban traffic calming measures during the past six years. It briefly describes the different measures and considers how changes in the dimensions, layout and spacing of the measures affect vehicle speeds. It also considers the effect of the measures on driver behaviour, passenger discomfort, traffic flows and accidents. Public reaction to traffic calming measures is included as well as the likely impact of the measures on vehicle generated noise, ground-borne vibration and vehicle exhaust emissions.
Abstract