Evaluation of the benefits of open graded friction course: Case study

Abstract

This study evaluated the benefits of Open Graded Friction Course (OGFC) via two field projects constructed by the Nevada Department of Transportation: one project was in Elko, and the other was in Las Vegas. Each project included both the OGFC and Dense-Graded Hot Mix Asphalt (DGHMA) sections. The Elko project was located in the town area of Elko while the Las Vegas project was constructed in a rural area on I-15 interstate highway. Laboratory tests were performed to evaluate the durability, rutting, and moisture-susceptibility of OGFC mixtures. The selected test methods included the Cantabro test, Tensile Strength Ratio test, and Hamburg Wheel-Track test (HWTT). The laboratory test results showed that the Las Vegas OGFC mixture passed all the performance criteria, but the Elko Mixture failed to satisfy the HWTT criterion.The field performance tests were conducted to assess the permeability, friction, and noise functionality over time. The selected test methods included the NCAT falling head permeameter test, locked-wheel skid trailer test, and On-Board Sound Intensity test. The field performance results demonstrated that the Las Vegas OGFC pavement exhibited benefits in permeability, friction, and noise reduction compared to the DGHMA pavement, while the Elko OGFC pavement showed comparable performance with the DGHMA pavement after 2-years of service. Finally, a cost-benefit analysis was conducted to monetize the advantages and disadvantages of OGFC pavements. As demonstrated in the economic analysis, the OGFC pavement in Las Vegas reduced the net present value of OGFC costs by 36%, while the OGFC pavement in Elko increased the net present value of costs by 86%. This indicates that the implementation of OGFC is cost-effective in rural highways but impractical in urban or town areas. High speed traffic is generally needed to help keep the interconnected voids of an OGFC pavement from becoming clogged over time. As a result of the reduced speed on the Elko project, the permeability functionality was lost after one year and the noise reduction benefit was lost after thirty two months.