A South African Road Network Classification Based on Traffic Loading

As South Africa’s road system comprises a total road network of rural and urban roads of approximately 534 000 kilometres, it is of utmost importance to have an effective road network level management system in place, which utilises reliable traffic loading data for long-term planning. Road authorities are therefore largely dependent on the availability and accuracy of traffic loading information to achieve the above and to assist them with their long-term strategic planning. In addressing these needs, this paper has three objectives. Firstly to evaluate the feasibility of the road network classification as presented by Bosman in 1988 after changes to the legal axle loads, which occurred in 1996. Secondly to revise the route classification system based on the actual traffic loading for the South African road network, if appropriate and finally to present a traffic loading reference guide for design, rehabilitation and maintenance purposes. Based on a literature review covering the South African and international vehicle and route classification systems, traffic loading data for South African road traffic routes are analysed. This comprises the analysis of traffic loading data collected at 301 Comprehensive Traffic Observation (CTO) stations along 40 different traffic routes. Utilising the South African National Roads Agency Limited’s (SANRAL) vehicle classification system, selected road traffic routes were divided in three classification categories, namely short (S-roads), medium (M-roads) and long (L-roads). Each of the three road classification categories represents a unique set of heavy vehicle characteristics, which are highlighted in this paper. Finally the South African rural road network is classified accordingly.