A 2020 FHWA study analyzed 157 treated curves across West Virginia, Pennsylvania and Kentucky to assess the impact of high-friction surface treatment (HFST) on crashes.

In Pennsylvania, Route 611’s treated curve reportedly saw no wet-pavement crashes for eight years after HFST installation in 2007, illustrating site-specific results rather than a universal guarantee.

HFST is not meant to overhaul entire highways but to target locations with concentrated friction-related crashes, and longer-term friction performance has proven durable under heavy traffic in separate studies.

Across three states, 329 crashes occurred after treatment versus an empirical-Bayes estimate of about 768 crashes would have been expected without HFST, with 82 wet-road crashes after treatment versus an expected 496 without it.

HFST bonds high-quality aggregate to pavement with a polymer resin binder, typically calcined bauxite, to improve tire grip, and targets curves, ramps and intersections where friction demands are high.

The strongest observed impact was on wet-road crashes, with a crash modification factor of 0.168, meaning the post-treatment rate was about 16.8% of the expected rate without treatment; roadway-departure crashes dropped 72%, injury crashes 48%, and opposite-direction head-on/sideswipe crashes 31%.

Results showed an estimated 83% reduction in wet-road crashes and a 57% reduction in total crashes at the treated curves, with all reductions statistically significant.