Paper presented at the 32nd Annual Southern African Transport Conference 8-11 July 2013 "Transport and Sustainable Infrastructure", CSIR International Convention Centre, Pretoria, South Africa.
Modern road pavement design requires the knowledge of axle loads. These are usually
obtained by means of Weigh-In-Motion (WIM) measurements. The WIM technology is
complicated and measurements are expensive. However, reasonably good estimates of
the axle-load distribution can be obtained by a method combining the current knowledge of
road and traffic with the WIM information obtained in the past. The method estimates the
distribution of axle loads that is likely to occur on a route with a certain type of axle-load
distribution, with a certain split of short, medium and long heavy vehicles, and under
certain intensity of law enforcement against overloading. The estimation method, called
ALDIS, was derived from a comparison of WIM records obtained under condition of no law
enforcement and strong law enforcement, and from an analysis of good-quality WIM
measurements done on 22 permanent sites in 2012. The axle-load distribution produced
by the ALDIS method can be used in mechanistic pavement design tools such as
cncPAVE, or Cyrano, to arrive at practical and economic pavement configuration.
