Study on pavement damage caused by axle overloading and associated costs in kenya

Abstract

Road transport remains the predominant mode of transportation in most developing countries for both freight and passenger traffic. To this end, most developing countries have invested heavily in improving the condition of their road network since the turn of the millennia. However, it is emerging that these gains are coming under increasing threat as a result of overloading vehicle axles. This study focuses on vehicle loading trends in Kenya. The study involved performing pavement life-cycle cost analysis using the Highway Development & Management (HDM-4) tool based on the concept of Equivalent Standard Axle Load Factor (ESALF). HDM-4 was used to determine annual road condition trends, road user costs, and yearly road works costs for two-axle loading scenarios; (i) using ESALF determined from the legal axle load limits, and (ii) those determined from independent field axle load surveys. The study revealed that axle overloading is still prevalent in Kenya, and that Kenya is losing about US$ 43 million per year to pavement damage as a result of overloading while collecting less than 10% of that amount in axle overloading fines. The study further quantified the average increase in road user cost per vehicle-km and additional maintenance costs due to axle overloading.