Urban Traffic Calming Measures - Design, Effectiveness, Public Attitude and Environmental Issues
LAYFIELD Rand WEBSTER D, Transport Research Laboratory, UK
Traffic calming measures are used to reduce speeds and consequently accidents. The original work on the development of a suitable profile for speed reducing road humps was canied out by TRL in the early 1970Õs and was based on circular profile (round-top)
Traffic calming measures are used to reduce speeds and consequently accidents. The original work on the development of a suitable profile for speed reducing road humps was canied out by TRL in the early 1970Õs and was based on circular profile (round-top) road humps of various dimensions. More recently, in order to improve the advice available to Local Highway Authorities in Great Britain, the Driver Information and Traffic Management Division of the Department of Environment, Transport and the Regions (DETR) has commissioned TRL to assess the effectiveness of a wide range of physical traffic calming measures used on public roads. The work has included measures involving vertical deflections (round-top humps, flat-top humps, speed cushions, sinusoidal humps.and ÔHÕ and ÔSÕ humps); and horizontal deflections (single lane working and two way chicanes).
This paper summarizes the results that have been obtained by TRL fiom a number of different test track trials and public road studies of urban iraffic calming measures during the past six years. It briefly describes the different measures and cokiders 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, iraffic flows and accidents. Public reaction to Mi c calming measures is included as well as the likely impact of the measures on vehicle generated noise, ground-borne vibration and vehicle exhaust emissions.
Changes in speed have been shown to be related to changes in injury accidents, with a 1 mph reduction in mean speed giving 5 per cent reduction in accident fiequency (Finch et al, 1994). This has been confirmed for traffic calmed areas by a number of studies (Webster, 1993; Webster & Macke, 1996).
Association for European Transport