Traditionally traffic calming has been applied to residential (Class 5) roads to deal the need to eliminate extraneous traffic from a residential area and/or to reduce speeds of vehicles using residential streets, both for obvious safety reasons. Local distributor (Class 4) routes can be defined as through routes that distributes traffic within communities and link district distributors routes and residential streets. These routes may accommodate the local bus/taxi routes, but should not carry extraneous traffic. Often non residential land uses such as community facilities and commercial uses are found along these routes. Local distributors therefore have both an access and a mobility function. The mobility function of these routes has to be preserved or else traffic will divert to the residential streets, thereby resulting in a traffic calming problem. Requests for traffic calming on Class 4 roads lead to a trade-off between mobility and safety. The paper presents a case study with the initial study of the traffic situation, the suggested strategy and an after study comprising intersection turning movement counts and travel time surveys together with accident data for the route and the traffic flow data. Average speed has decreased drastically and the 85th percentile speeds is now well below the posted speed limit. Vehicular flows have reduced, thereby indicating that the reduced speeds on the route have resulted in a diversion of some traffic to parallel routes. The frequency of accidents has been reduced by approximately 80 per cent, while the frequency of slight injury accidents has reduced by approximately 70 per cent. Over the past two years, the occurrence of serious injury accidents appears to have been eliminated.
Abstract