U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
The friction provided by a roadway surface affects how vehicles interact with the roadway. Measuring, monitoring and maintaining pavement friction can prevent many roadway departure and intersection related crashes, resulting in fewer serious injuries and fatalities.
More than 50 years ago, National Cooperative Highway Research Program (NCHRP) Report 37 stated that "the lowest friction levels are found on high-speed roads, curves and approaches to intersections; in short, in locations at which high friction values are needed most." ssentially, this research recognized that friction varies as you travel down the road and that a clear friction "supply and demand" relationship exists, and is a factor in determining the safety performance of a road. The current state of practice for high speed friction measurement by State DOTs is the locked wheel skid trailer which is a discrete, sample-based approach, and thus does not effectively differentiate the changes in friction along the route corridor.
CPFM is an established and proven approach that has been used for several decades in other countries, and could revolutionize the role of pavement friction in framing our understanding and management of the safety performance of our Nation’s roads. This approach is commonly used by road authorities in many European countries, Australia and New Zealand, and even by airport authorities in the U.S. to measure friction on runways. CPFM equipment is able to measure pavement friction continuously, through tangents, curves and intersections.
A recent study by FHWA confirm that CPFM data, combined with crash data and road characteristics, provide significant insight regarding whether friction improvements may reduce crashes. FHWA encourages the use of CPFM to provide comprehensive pavement friction data, combined with existing safety data and analysis, to create an overall pavement friction management program anchored in safety.