No Gaps: Kentucky Pilots New 

Friction Management Approach

Roadway departure (RwD) and intersection crashes make up 75 percent of all traffic fatalities in the U.S. 

Many of those crashes come down to how vehicle tires interact with the pavement of the roadway. In 

other words, adequate pavement friction to meet friction demand is crucial to roadway safety. That means 

agencies need reliable methods for measuring pavement friction to meet safety performance goals. 

In Kentucky, 60-70% of their yearly highway fatalities are the result of roadway departures. Those crashes 

have an annual economic impact of over $10 billion, as well as life-changing effects on Kentucky residents.

“We’ve reframed the way we think about roadway fatalities overall,” said Michael Vaughn, traffic safety 

branch manager at the Kentucky Transportation Cabinet (KYTC). “It’s much more proactive and about 

preventing the next crash, not reacting to the last one. We’ve started thinking that way about managing 

friction on our roadways.”

Recently, the KYTC piloted a program that uses Continuous Pavement Friction Measurement (CPFM) 

to better measure and manage friction on Kentucky roadways. CPFM equipment measures pavement 

friction continuously, through tangents, curves, and intersections at speeds as high as 50 mph, 

eliminating data gaps created by other friction-testing methods that are not continuous. 

KYTC used CPFM to collect friction data on 15,118 lane miles of its 63,878 total lane miles. Data were 

collected on interstates, parkways, and State primary and secondary routes, as well as ramps on all these 

facility types. 

Credit: Texas Transportation Institute
The data included friction coefficient (SFN40), texture (mean profile depth), curve radius, grade, cross

slope, and GPS coordinates. This information was incorporated into the State’s Linear Referencing

System (LRS) and then the roadway network was divided into 0.1-mile-long analysis segments. Each

segment was assigned to a site category, such as curves with a radius of less than 300 feet, curves 300-

700 feet, intersections, tangents, etc.

From there, KYTC developed a network-level safety performance function that helped predict the crash

reduction for each site category along the various KYTC-managed route systems if friction were increased

by 10 points. A 10-point increase in friction corresponds to increasing a pavement’s coefficient of friction

by a value of 0.1.

The analysis showed that a 10-point increase in average friction across the network would lead to a 

crash reduction of over 10% of all crashes. This could save many lives and serious injuries as well as save 

Kentucky residents more than $1 billion per year. Treatments such as resurfacing, microsurfacing, chip 

seals, shot blasting, and diamond grinding typically provide a 10-point or higher increase in friction. 

Other treatments, such as high-friction surface treatment (HFST), can provide a 30-40 point or higher 

increase in friction. With a wide variety of friction treatment options available, KYTC is confident that 

utilizing CPFM will allow for better management of pavement friction and over time will achieve a 10-

point increase in average friction across their roadway network.

“This has helped us reassess how we see our whole network,” Vaughn said. “We used to focus more on 

our high-volume roads and freeways because of the increased traffic. But this study has shown us that 

we have real opportunities to save lives on lower-volume roads because they can have more challenging 

geometry and contextual issues that friction management can help.” 

KYTC is using the CPFM data to identify locations where friction enhancements may be worthwhile. 

Transportation practitioners at KYTC plan to use their experience with CPFM in many ways going 

forward. They are using friction and texture data to identify locations for the installation of HFST. A few 

dozen sites have been prioritized for installation of HFST during the 2023 construction season and more 

will be prioritized for installation during the 2024 construction season. They are also working to 

incorporate more strategic use of HFST, as well as other friction and texture enhancing treatments. 

Additional plans include incorporating friction and texture measurements in the scoring matrix used to 

prioritize pavement resurfacing projects, improving mix designs and materials specifications, and more.

“I truly believe CPFM is an opportunity to make significant strides in reducing severe crashes nationwide 

and help us achieve our safety goals,” Vaughn said.

For More Information:

FHWA Office of Safety

Jeff Shaw

jeffrey.shaw@dot.gov

FHWA Resource Center

Andy Mergenmeier

andy.mergenmeier@dot.gov FHWA-SA-23-017

Watch an FHWA video on CPFM. Find case study summaries, best practices, and more on CPFM. 

Pavement Friction Management using CPFM is a Proven Safety Countermeasure and is consistent 

with the Safe System Approach.