Study Of Optimal Travel Speed Limits For Shared Traffic PDF Download

This thesis identifies and investigates three specific speed related topics, namely the relationship between speed and safety, the effect that various factors have on vehicle speeds, and how a reduction in speed behaviour can be effectively influenced. Initially, the effect of speeds on the number and severity of road traffic accidents is examined. A case study is undertaken on a National Route on the approaches to an urban area in order to examine the speed behaviour of the road users. The effect that speeds have on road safety are investigated by examining accident data and by conducting conflict studies. The second speed related topic involves the identification of the main factors that influence the choice of speed on any road. These principal factors, namely the human, the road environment and the speed limits, are identified and their effects on traffic speeds are assessed. A comprehensive speed study is carried out on the approaches to and inside speed limit zones so as to establish the effect of these speed limits on actual vehicle speeds. These actual speeds are compared with an Ideal Speed Adaptation Model for these speed limit zones. Various measures which can be effectively used to influence the speed choice are also examined. These countermeasures include areas of enforcement of traffic law, education and training of the road users and the introduction of engineering techniques to restrict travel speeds. The application of some of these countermeasures to two different high speed National Routes is also examined. Finally, conclusions are are drawn concerning these three speed related issues. The thesis also provides recommendations in order to minimise the effects of travel speeds on interurban roads.