TYRE-PAVEMENT INTERFACE CONTACT STRESSES ON FLEXIBLE PAVEMENTS – QUO VADIS?

Worldwide, road pavement networks are constantly under pressure of an ever increasing demand from economic and other market forces. As a result, road infrastructure needs constant protection and it is therefore necessary to understand the ever-changing operating conditions such as the impact of heavy vehicles (HVs). Since the previous CAPSA 1999 conference further progress has been made with the application of Stress-In-Motion (SIM) technology to assist in the quantification of tyre-pavement interaction. An up-graded 4-pad system was recently used at the Traffic Control Centre (TCC) on the National Route 3 (N3) near Heidelberg in South Africa. The aim of this paper is to highlight the use of SIM technology on typical HVs found at this site (N3-TCC), with illustrative examples on real world trucks on this highway. A summary of the findings on tyre inflation pressure on this route is also given. Finally, the paper discusses an improved definition of the actual tyre/pavement interaction of modern heavy vehicles and their loads on the current flexible road infrastructure. A simplified method is used as an example to illustrate the application of improved tyre loading models that could be used for thinly surfaced flexible pavement design methodologies in future. The effect on maximum horisontal tensile strain as a direct result of a weak bond at the bottom of the thin asphalt surfacing is also discussed