The development of road safety assessment screening procedures for the city of tshwane metropolitan municipality

Abstract

In the global context, South Africa, as characteristic of many developing countries with limited resources, faces the challenge to proactively manage, reduce and eliminate the high incidence of road crashes, injuries and fatalities. Due to an absence of practical Road Safety Assessment and Audit procedures within the relevant departments at the City of Tshwane Metropolitan Municipality (CTMM), the main aim of this research was for the development of procedures with measurable benefits in promoting a safer road environment. The research scope is limited to road safety engineering and the road network within CTMM boundaries. However, aspects of the study can be generalised to other municipalities. The research used data from the CTMM accident database, traffic count database including road classification, and design information from the ARCGIS system, to determine a linear regression model for accident rate prediction. The model can be used to establish screening procedures for effective prioritisation of scarce funding as well as a safety comparison of selected intersection control types. Intersection controls and traffic safety measures such as traffic signs, traffic circles and traffic signals were assessed for effectiveness in reducing the Rate of accidents per Million of Entering Vehicles (RMEV’s). The results show a relationship between Average Daily Traffic (ADT) and Accident Frequency. The linear regression equation allows for the prediction of crash rates and the prioritization of road safety projects. The findings in addition illustrate approximately a twofold increase in accident rates on higher order roads, typically traffic signal-controlled intersections. Factors such as a greater number of intersection conflict points, greater pedestrian volumes and increased intersection saturation or volume/capacity levels contributed to higher accident rates.