Bristol is one of five cities and towns involved in the Urban Safety Project led by the Transport and Road Research Laboratory (TRRL) to demonstrate the effects of combining, on an area-wide basis, a range of low-cost engineering measures to reduce accidents. In 1986, after gaining the acceptance of local residents, a package of interacting countermeasures was implemented in an area in the north of Bristol. The scheme was based on retaining substantially the existing network of arterial and distributor roads, and trying to encourage through traffic to keep to these, thereby minimising traffic within residential areas. Many junctions on and between distributors and arterial roads were improved, and a number of junctions with residential access roads were closed or had turning prohibitions imposed. In the latter respect, particular attention was given to one residential area which had been experiencing disproportionate numbers of accidents. These changes were achieved without appreciable extra delays to traffic. The effect on accidents was to have been assessed by comparison with a similar area chosen beforehand, but some unexplained changes in accident occurrence in this area led to the use of a wider area for comparison. On this basis, the reduction of injury accidents during the first two years of operation of the scheme is estimated to have been in the region 10 to 25 per cent. Accidents to users of motorcycles and mopeds was reduced by more than the average for the area, and no road-user group experienced an increase in accidents.

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