The Pennsylvania Department of Transportation, in partnership with Pennsylvania State University, published a report that quantifies the safety effects of high-friction surface treatment (HFST) on pavement at horizontal curves and intersections across the state.
Pavement friction, or skid resistance, influences road safety performance. As pavement gets polished and friction decreases, crash potential increases—especially for maneuvers such as steering, turning, braking, or accelerating. When pavement is wet, friction becomes even more critical. Consequently, road agencies must manage pavement friction throughout the entire pavement lifecycle. Recognizing that, FHWA adopted Pavement Friction Management as one of the updated proven safety countermeasures in 2021.
HFST, one of the tools for managing pavement friction, is a surface enhancement applied to existing pavement. HFST consists of a durable, gritty, and highly polish-resistant aggregate layered within a polymer resin binder that bonds to the pavement surface. HFST is ideally suited for targeted locations the need more friction, such as horizontal curves, ramps, and intersection approaches. Improving friction at these high-friction-demand locations can help vehicles maintain control and effectively reduce braking or stopping distance, which in turn can decrease speed and kinetic energy in case of a collision.
The Pennsylvania study developed crash modification factors (CMFs) for severe (fatal and injury) crashes, total crashes, and various crash types. The data set included over 57 treated miles with 700 horizontal curves and 33 intersections, making it one of the largest studies of its kind in the US.
For horizontal curves on two-lane rural roads, the Pennsylvania study found that application of HFST led to a reduction of fatal and injury crashes by 48 percent. The findings were consistent with results from other US studies and confirmed that HFST is a highly effective strategy for mitigating run-off- road crashes at curves.
This study is particularly notable for developing CMFs for applying HFST at intersections, including stop-controlled and signalized, in urban and rural contexts. For this scenario, the analysis found a combined reduction of fatal and injury crashes of 76 percent.
Learn more:
- Crash Modification Factors for High-Friction Surface Treatment in Pennsylvania (Pennsylvania DOT, 2023)
- FHWA HFST website
- Every Day Counts Biweekly Newsletter, April 18, 2024
- Evaluation of Thin Polymer Overlays for Bridge Decks (Montana DOT/FHWA, 2023)