Axle Load Distribution Characterization for Mechanistic Pavement Design

In Sri Lanka, Overseas Road Note 31 and AASHTO method are the most frequently used pavement design methods. However, in these methods the consideration given for utilization of readily available in-situ materials and incorporating characteristics of substandard materials into the designs, is not significant. On contrary, the AASHTO Mechanistic-Empirical (M-E) method of pavement design allows the designer to utilize in-situ materials and allows to optimize the pavement design to suit the conditions at site. However, due to the amount of data input required in M-E design, the preference of local practitioners in using the M-E method is not satisfactory. This study was carried out with the objective of identifying trends in axle load group type distributions of different regions in Sri Lanka. It has been found that there are similar patterns in distribution of axle group types throughout the island. Also, it was found that there are certain geographical regions with similarities in pavement loading conditions. An attempt for zoning traffic load distributions for selected geographic areas is presented in this study. This will aid in determining the traffic data input for M-E design, with a degree of accuracy level 2 as defined in M-E design method.