ECONOMIC ANALYSIS OF AXLE-LOAD LIMITS IN LESS-DEVELOPED COUNTRIES

Overloaded vehicles contribute significantly to the deterioration of road surfaces. Most jurisdictions provide protection against severe pavement deterioration by enacting legislation that limits permissible axle loads. In most cases, axle-load limits are determined without reference to economic viability. Axle-load limits in less developed countries are obtained from experience in developed countries, where axle-load distributions, truck fleet composition, and adherence to regulations may differ significantly. An analysis is presented in which economically viable axle-load limits are established when the additional costs from pavement deterioration due to higher axle-load limits are offset by the benefits from reduced vehicle operating costs. With reference to this criterion, axle-load-distribution data from Abu Dhabi are used to establish economically viable axle-load limits. The dominance of vehicle operating cost savings due to higher limits submerges any additional costs due to pavement deterioration in the analysis. This suggests that economically viable axle-load limits in Abu Dhabi should be set to maximum feasible levels where bridge loading restrictions come into effect. This conclusion is amplified for less developed countries in general by considering sources of additional revenues. These additional revenues would be necessary to restore road serviceability after accelerated pavement deterioration from the application of higher axle loads. (Author)