Investigations and proposals for investigatory level requirements for skid resistance of south africa’s roads

Abstract

With South Africa’s high incidence of serious road accidents there is a need to provide the country’s roads with effective skid resistance characteristics in all weather conditions. Currently there are no skid resistance requirements specific to South Africa, and reliance is placed rather on the Polished Stone Value of the aggregate used in chip seals and asphalts, and to a certain extent on surface macro texture. Recent studies have found these two methods of assessing skid resistance to be highly unreliable at the higher speeds at which a large proportion of road collisions are initiated. In an attempt to improve the status quo, investigations have been undertaken using a specialised vehicle that measures the sideways force coefficient of the road’s surface in both wheel tracks. This vehicle also has the capability of simultaneously carrying out continuous texture measurements and enables large sets of surface friction and texture data to be collected for detailed analysis and identification of sites requiring a more detailed investigation of skid resistance. This paper presents the methodology of the investigation; the results obtained and discuss proposals for the formal adoption of skid resistance investigatory limits appropriate to South Africa’s road conditions.