This project for the Swedish National Road Administration examines the international literature on traffic calming in urban areas with a view to identifying methodologies and design ideas which have been developed and monitored in a wide range of different conditions. The literature review covers the context in which traffic calming should be used, including national policies and legal arrangements. It also looks at the detailed design of traffic calming measures and reviews their effects. Within the review consideration was given to: · Different types of urban area · The value of Urban Safety Management as a guiding set of principles · Environmental effects · Effects on mobility of all road users · Different road users · Effects on speeds · Effects on traffic flows · Effects on accidents and potential problems of accident migration · Special considerations for public transport, heavy goods vehicles and emergency vehicles · The need to create attractive town environments for all users · The effects on commercial activities · Social effects · The need for legislation · International comparisons This literature review has shown that traffic calming is now a major part of the treatments available to safety engineers to reduce road accidents in urban areas. Although there are some early historical examples of attempts to control speeds it is really from about 1970 that traffic calming began to appear in its modern form. It was Northern European countries, particularly Holland, which gave the lead, but traffic calming is now in use world-wide. There was initially considerable resistance to the introduction of traffic calming, particularly from car drivers and those organisations that represented them. The result of this was that rules and regulations introduced by national governments on how to implement traffic calming were quite restrictive and as a result progress on implementation in many countries was slow. Since the 1980s this situation has changed and many national governments now actively encourage local authorities to implement traffic calming, even to the extent of providing funding for it. Generally the countries that introduced traffic calming had a more or less specified legal framework and specification guidelines for the design of measures. For some countries there was strong central government control of design, for others much more delegated responsibility to local authorities and their engineers. Many technical guidelines have also been produced on traffic calming. A principa l recommendation is that traffic calming should not be used piece-meal, but rather should fit into an integrated strategy which considers all roads in an urban network. This strategic approach is referred to as Urban Safety Management and the EU has recommended member countries to adopt its use when tackling urban accidents, which tend to be scattered and therefore not amenable to the traditional single site treatment. The effects of traffic calming on safety have been shown to be good. Virtually all schemes have reduced casualties, often by more than 50 per cent. Research has shown that there can be both positive and negative environmental effects resulting from traffic calming schemes and that these environmental changes are dependent on the traffic calming measures used, the volume and composition of the traffic stream, the speed reduction obtained and any changes in driving style. Before and after studies in a number of towns revealed that traffic calming schemes had a positive affect on retailing. The research indicated that the number of pedestrians visiting traffic calmed shopping areas increased substantially after implementation. Public opinion about traffic calming is generally favourable although there is often a vociferous minority against its use. Good consultation can minimise opposition. A great variety of measures are described in this review. They are mainly some form of vertical or horizontal deflection. Most commonly used are vertical measures, usually speed humps or speed cushions, but the use of different types of speed cameras is also common in some countries. The review provides recommendations on best design and outlines the effects of the different measures identified. (Author/publisher)
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