Road demand and road wear

Heavy trucks benefit the community by carrying freight more cheaply than lighter (smaller) trucks only if their extra costs, particularly the cost of repairing any additional deterioration to the highway network, are contained. Therefore, to achieve rational pavement management, it is necessary to estimate the relative deterioration caused by trucks of different types carrying different levels of payload. In particular, reliable data is required to provide for truck cost recovery and regulation with respect to pavement damage. A brief description is given of how the fourth power law is used to estimate the damaging effect of different axle loads on pavements. The types of vehicle surveys required to obtain data concerning the demands on road pavements by trucks and the relationship between power laws, demand data and load limit enforcement are discussed.