Investigation of the Influence of the Condition of Asphalt Pavement Surface on Road Safety of Rural Ontario Highways

Abstract

Road collisions are complex events that are influenced by a combination of factors, including driver behaviour, environmental condition (e.g., icy and wet roads), road geometry, roadside elements, vehicle speed, tire deficiencies, traffic, and pavement condition. While the influence of some of these factors has been studied extensively for decades, the influence of pavement condition on road safety is relatively under-researched. This research investigated the influence of pavement surface condition on road safety by developing statistical models that correlate pavement surface condition and collisions. This research also examined the possibility to integrate skid resistance into pavement management by investigating the correlations between skid resistance, pavement distress, and operational conditions of the roads. This study was limited to rural arterial and freeways of the Ontario asphalt pavement road network. Data of pavement condition, operational condition, and collision was obtained from the Ontario Ministry of Transportation for 6879 kilometers across 37 provincial rural highways for the period of 2012 to 2014. Pavement condition data was collected at network level with an automatic road analyzer road and included information about roughness, rutting, cracking, and macrotexture. Skid resistance data was collected with a locked wheel tester. The collected data was combined into a spatial data model, also known as a vector-based geographic information system. The results of the investigation using regression analysis showed that pavement friction is affected by traffic, pavement age, and pavement distress. Skid resistance decreased with the increase of traffic and increased with the increase of pavement distress. Macrotexture increased with the increase of traffic and pavement distress. The influence of pavement condition on road safety using statistical analysis and regression models indicated that collisions were lower for pavements in fair condition and greater for pavements in poor and good condition. Pavement texture also showed to be an important factor for collision classes that demanded satisfactory levels of macrotexture and pavement friction. In particular, greater levels of macrotexture contributed to a reduction in sideswipe and wet surface collisions.