The structural wear of road pavements: an assessment of the fourth power law on the A1(M) motorway in County Durham

This Paper records the results of an audit which has examined the structural performance of a heavily trafficked public road in Durham County. A detailed history of the construction, maintenance and classified traffic flows for the road was available from Durham County Council (DCC) and, together with typical axle loads from the Traffic Loading Unit, University of Newcastle upon Tyne, the study estimated actual exponent values for sections of public road assuming that a power law relationship existed between structural wear and wheel load. The study showed that the actual power exponent values were between 0.02 to 7.16 and, for exponent values that were significantly different to 4, an initial pavement design life of 20 years would no longer minimize whole life cost. The consequences of this finding are far-reaching for the design and management of road pavements.