Long Term Performance and Acoustic Properties of an Aging Open Graded Friction Course Asphalt Pavement Surface

This paper describes a long term follow up study carried out by the British Columbia Ministry of Transportation and Infrastructure (BC MoT) on two developmental paving projects constructed in the mid 1990’s using Open Graded Friction Course asphalt concrete pavement (OGFC). These projects were on Vancouver Island in a wet/no freeze climate. OGFC pavements have a much coarser gradation, significantly higher air voids, and greater asphalt film thickness than conventional asphalt pavements. Benefits include improved safety due to increased skid resistance, improved surface drainage, reduced glare, and reduced spray during wet conditions. Substantial reduction in ambient traffic noise due to the noise attenuating qualities of OGFC significantly improves driver comfort and reduces driver fatigue. The reduction of noise is also a significant benefit to people living near roadway facilities which have been surfaced with OGFC. The study focuses on two projects constructed in and near Nanaimo BC in 1995, 1996 and 1997. One was constructed in two phases on Highway 19A in the City of Nanaimo. The other project was constructed on Highway 19 which was a new highway built to service the Duke Point Ferry Terminal. The paper presents recent and past measurement data regarding these pavement characteristics, and analysis of the long term performance of the pavement in terms of the following pavement characteristics: • Traffic noise attenuation • Skid resistance • Pavement roughness in terms of International Roughness Index • Pavement condition in terms of Pavement Deterioration Index • Rut depth • Remaining pavement life as determined using AASHTO 1993 Guide for Design of Pavement Structures using data from Falling Weight Deflectometer testing • Permeability A call for traffic noise reduction is often expressed during public consultation in advance of major projects in BC. The environmental benefit of reduced noise was of significant interest to the Ministry. MoT has a noise policy dating from 1993 that identifies where project-related noise impacts warrant mitigation and that the use of "quieter pavements" can be a component of such mitigation efforts. The follow up on these past projects will be used to gauge the long term effectiveness of this surface course type and will influence policy decisions regarding asphalt surface course specifications.