Longitudinal profile and rut depth have been monitored over a period of six years on over one thousand, twenty metre long test sections spread over motorway and trunk road sites using the TRRL High-speed Road Monitor (HRM). Trends in profile with time were compared with assessments of structural condition using visual inspection, and deflection. Changes in longitudinal profile for features of less than three metres wavelength over a period of two years were found to reflect significant pavement deterioration as assessed by visual inspection. Also, this measure of profile change was found to increase significantly with a decrease in the residual life of pavements as estimated from deflection under a rolling wheel. Criteria, based on the proportional change in longitudinal profile have been defined for use in detecting significant pavement distress in fully flexible pavements and those with a lean concrete roadbase. The application of these criteria to surveys made with the HRM is described and the combination of machine and criteria is shown to provide an efficient and economic means of locating deterioration in the road network. (A)

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