While standard road surfaces may appear adequate to motorists, their ability to maintain tire grip can degrade rapidly once it begins to rain. On sharp, winding roadways, this sudden loss of traction significantly raises the danger of a vehicle sliding off the path. To combat this hazard, transportation agencies have increasingly turned to high-friction surface treatments, commonly known as HFST.
A comprehensive 2020 Federal Highway Administration study evaluated the performance of these treatments by analyzing 157 curves distributed across West Virginia, Pennsylvania, and Kentucky. Researchers discovered that wet-road crashes plummeted by an estimated 83 percent following the application, while overall traffic accidents declined by 57 percent. These statistically significant outcomes highlight the value of deploying targeted grip enhancements at high-risk locations.
Driving through a curve requires pavement to supply adequate friction so tires can hold their trajectory. When precipitation reduces this available traction, motorists face a narrower margin of error. HFST addresses this issue by bonding durable, high-quality aggregate, such as calcined bauxite, to the existing pavement using a specialized polymer resin binder. Instead of resurfacing entire highway corridors, agencies apply the treatment selectively to accident-prone zones like sharp curves, highway ramps, and hazardous intersections.
The 2020 research employed an empirical Bayes before-and-after statistical methodology to control for variables like traffic volume fluctuations and underlying trends. Average annual traffic volumes across the analyzed sites ranged between 6,000 and 8,000 vehicles depending on the state. The analytical model compared actual post-treatment accident figures against the higher number of collisions that would have been statistically expected without the intervention.
Beyond the dramatic drop in wet-weather incidents, the data showed substantial improvements across other accident categories. Roadway-departure accidents dropped by 72 percent, injury crashes fell by 48 percent, and opposing-direction collisions involving head-on or sideswipe impacts decreased by 31 percent. In total, the study recorded 329 actual crashes post-treatment compared to an estimated 768 expected accidents, while wet-road incidents numbered 82 against an expected 496 without intervention.
Additional evaluations conducted concurrently in Georgia and Pennsylvania demonstrated that HFST retains its friction capabilities over extended periods under heavy traffic loads. More recent investigations, including a 2024 analysis in Pennsylvania utilizing advanced matching methods, have continued to validate these safety benefits. Although exact percentage reductions can vary based on local traffic, weather, and driving behavior, highway authorities view the treatment as an effective way to improve safety without undertaking costly roadway reconstruction.