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Federal Highway Administration Research and Technology
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Publication Number: FHWA-RD-99-089
Date: December 1999
Research, Development, and Implementation of Pedestrian Safety Facilities in the United Kingdom
8. Traffic Calming, Speed Reduction, and Pedestrians
8.1 Recent UK traffic calming
Traffic calming has been the focus of much research, development, and implementation in the past decade as the United Kingdom has sought to catch up in this field with other European countries such as Holland, Germany, and Denmark. The Traffic Calming Act 1992, The Highways (Traffic Calming) Regulations 1993, and The Highways (Road Humps) Regulations 1996 have clarified and increased the powers of UK highway authorities to introduce traffic calming measures and to be more innovative. More recently, 32 km/h (20 mi/h) speed limit zones have been introduced where the lower speed limit is enforced by physical measures. The DETR allocates some £60 million ($98 million) per annual to local highway authorities in England for Local Safety Schemes and a substantial proportion of this now goes for traffic calming schemes (Tootill and Mackie, 1995).
Traffic calming refers to a wide range of physical measures, including vertical and horizontal deflections, changed surfaces, planting, etc. It may include specific facilities for pedestrians, such as pedestrian refuges, curb build-outs, entry treatments, or Zebra crossings; and these features are reviewed in section 5 above. Although traffic calming is not a pedestrian facility, it can be parti- cularly beneficial to pedestrians as they are most vulnerable to excessive speed even on 48 km/h (30 mi/h) roads which was until recently the lowest permitted speed limit for a public road.
The standard height for road humps is now set at 75 mm which has been found to be just as effective at reducing vehicle speeds as the 100-mm humps (Webster and Layfield, 1996). Flat-top humps provide easier crossings for pedestrians and can be combined with Zebra crossings, although they are generally more uncomfortable for bus passengers than round-top humps.
Side road entry treatments — usually flat-top hump in combination with curb build-outs and other physical measures — can be provided to help pedestrians cross side roads. This creates greater route continuity for pedestrians and reinforces the Highway Code rule that drivers turning into side roads should give way to pedestrians who are crossing.
Although traffic calming is considered to have substantial casualty reduction effects, the United Kingdom’s approach has been criticized for over-reliance on physical measures, particularly road humps, and a lack of attention to aesthetics, changing driver attitudes, or integration with wider transport and environmental policy objectives. Some measures have had adverse consequences for emergency services, bus users, and cyclists.
Figure 11. Examples of pedestrian guardrails.
8.2 32 km/h (20 mi/h) zones
Thirty-two km/h (20 mi/h) zones appear to be highly successful at reducing vehicle speeds and casualties. Webster and Mackie (1996) found that the average all accident frequency fell by 60 percent and that child pedestrian accidents were reduced by 70 percent. There was a 6.2 percent reduction in accidents for each 1.61 km/h (1 mi/h ) reduction in vehicle speed. At the time of reporting, there were over 200 32 km/h (20 mi/h) zones in the United Kingdom of which 82 had been granted permanent status. (See figure 12.) While this seems a very encouraging initiative, it must be remembered that the 32 km/h (20 mi/h) zones are relatively small areas, excluding linear sites, the average size of a 32 km/h (20 mi/h) zone is 0.28 km and the cost of applying these techniques to the majority of residential roads is prohibitive. PACTS (1996) and others have suggested trials of 32 km/h (20 mi/h) limits without fully-enforcing physical measures, equivalent to the 30 km/h (19 mi/h) limits adopted throughout the city of Graz, Austria, on all roads except a few strategic routes where 50 km/h (31 mi/h) limits apply.
8.3 Other speed reducing initiatives
Some UK local highway authorities are developing speed management plans. York (Pheby, 1997) found strong public support for a plan which categorizes all roads into traffic, mixed priority, or residential, with appropriate speed management and enforcement policies. The city of Gloucester has been selected for the 5-year Safe City project which involves a combination of physical and other safety measures, including speed management, on the basis of the Urban Safety Management guidelines (IHT, 1990).
A range of ambitious measures, including lower speed limits and speed governors in vehicles are proposed by PACTS (1996), the European Transport Safety Council (1995), and Plowden and Hillman (1996). However, lowering speed limits in urban areas does not feature as an option in the DETR's recent review of road safety strategy (DETR, 1997b).