Cost estimation of road wear due to heavy vehicles on the Namibian paved network

Abstract

This paper presents the results of a newly-developed methodology that quantifies the road wear caused by heavy vehicles on the Namibian paved road network in terms of equivalent standard axles and a monetary value. This was achieved by converting the spectrum of heavy vehicles travelling on the Namibian trunk road network per road section in one year to an equivalent number of standard axle-km travelled in the same year and multiplying the standard axle-km by the estimated unit construction and maintenance costs per uniform pavement section on the road network. The conversion of the spectrum of heavy vehicles to an equivalent number of standard axle-km travelled involved the calculation of load equivalency factors for the different vehicle configurations using the South African Mechanistic Empirical Design Method, which is based on data obtained from the Heavy Vehicle Simulator (HVS) and Stress-In-Motion (SIM) systems over the past few decades. Data obtained from the Namibia Roads Authority included traffic count data, weighbridge data, road network data and pavement data. This study has allowed for the development of a suitable platform to efficiently, and with improved accuracy, calculate the cost of road wear caused by heavy vehicles on the Namibian paved road network. The developed methodology will enable the Roads Authority to monitor changes in the road wear costs attributed to heavy vehicles. It also provides the Road Authority with a tool to determine the effect of initiatives such as improved overload control and for making more informed strategic decisions.