Developing the automatic measurement of surface condition on local roads

Following the successful application of traffic-speed surveys on the English motorway and trunk road network, the UK Department for Transport has introduced traffic-speed surveys on the local road network, to provide fully automatic measurement of the surface condition. These surveys aim to meet the needs for national reporting of condition, whilst providing data of value for local engineers. To meet these dual goals required that suitable parameters be developed to identify the defects of key importance on local roads. A significant programme of research was commissioned by the Department for Transport to develop these. Firstly, new parameters assessing ride quality have been developed that identify areas of most concern to the road user, in particular where there is localised roughness that causes vehicle jolting. Secondly, new parameters have been proposed that exploit the potential of texture and transverse profile measurement systems in the measurement of surface deterioration across the full width of the pavement. Finally, a fully automatic method has been implemented that aims to identify deterioration, such as stepping and subsidence, developing at the outer edges of minor local roads. Each of these measures was assessed through comparison with conventional site surveys, and they have subsequently been implemented in the national survey of local roads.