TOTAL CRASHES

(Per Year)

WET CRASHES

(Per Year) NET ANNUAL BENEFIT

SAFETY

COST BENEFIT

TIME SAVINGS

CASE STUDY

SOUTH CAROLINA

US 25-Greenville County

HIGH FRICTION SURFACE TREATMENT (HFST)

A one-mile section of US 25 in Greenville County 

had been a cause for concern for the South Carolina 

Department of Transportation (SCDOT) for many 

years. Located in rural, mountainous terrain, and often 

subject to inclement weather including rain, snow, 

ice, and fog, US 25 carries traffic on two lanes in each 

direction and is separated only by a damaged and 

brittle concrete barrier. US 25 changes dramatically, 

from a relatively straight road in North Carolina 

directly to this particular section in South Carolina 

with horizontal and vertical curves and a 6 percent 

grade. US 25 has a speed limit of 55 mph and carries 

approximately 10,000 vehicles per day with heavy 

truck traffic. 

SCDOT discovered a number of factors contributing to the high crash rates along this short section of US 25. One 

significant factor was that the concrete barrier’s design did not allow for proper drainage, channeling water to the 

driving lane and shoulder. Speeding, inadequate pavement superelevation, and sight distance constraints also 

contributed to the safety issues at this location.

In 2000, SCDOT considered funding a major reconstruction project which involved replacing and updating the barrier 

wall and modifying the roadway’s superelevation and drainage structures. However, with the project’s estimate coming 

in at nearly $5 million, this project was unlikely to happen. Both costly and lengthy, the overall project development 

timeline for this alternative would have spanned approximately three years, and would have involved an extensive 

work zone and detour which would have inconvenienced local residents and drivers traveling through this area.

9.6

8.1

4.2 2.6

Before After Before After HFST RECONSTRUCTION 

ALTERNATIVE

A Cost-Effective and Time-Sensitive Safety Solution

56.5%

decrease

68.1%

decrease $

80%

savings

vs.

$1 M

$5 M

6 Months

TO IMPLEMENT

HFST

3+ Years 

DESIGN/CONSTRUCT

RECONSTRUCTION 

ALTERNATIVE

6 Months

TO IMPLEMENT

HFST

3+ Years 

DESIGN/CONSTRUCT

RECONSTRUCTION 

ALTERNATIVE

MP 52.19

GREENVILLE US 25 ©Google Maps

MP 53.22
SOUTH CAROLINA

HIGH FRICTION SURFACE TREATMENT (HFST)

Over the years, low-cost measures of additional signing 

and markings were added along US 25, but these did not 

adequately address the excessive speeds and drainage 

issues, and the resulting safety improvement was minimal 

at best. At one point, a dynamic message sign (DMS) was 

installed to display a regulatory 45 mph speed limit during 

rainy conditions. However, due to the rural nature of 

this road segment and the wide road template, speeds 

remained excessive.

In 2008, a High Friction Surface Treatment (HFST) was 

applied to this curvy stretch of US 25. SCDOT had used 

this pavement treatment on ramp segments to increase 

skid resistance in locations where friction demand was 

high, but this one-mile project was the largest application 

to date, and at the time, it was unclear whether 

HFST would mitigate the hydraulic issues motorists 

experienced on this segment. With the planning 

process and installation complete in approximately six 

months, the HFST project cost SCDOT $1 million, which 

was 80 percent less than the previously considered 

reconstruction project. 

A before and after study evaluating the HFST project’s 

success on US 25 revealed significant safety benefits, 

with a 68 percent reduction in wet crashes and a 56 

percent reduction in total crashes. Six years after HFST 

installation, SCDOT reports the pavement treatment is 

holding up very well, considering the high exposure to 

snow plowing.

To develop its current HFST specification, SCDOT used 

the AASHTO specification as the base model and 

integrated pieces from other States’ specifications as 

well as their own experiences with the treatment. While 

their HFST specification is still evolving, SCDOT believes 

it strikes a good balance between quality materials and 

application, while still maintaining reasonable contractor 

expectations and competitive bidding.

BEFORE AFTER

Frank Julian

FHWA Resource Center

frank.julian@dot.gov

Joseph Cheung

FHWA Office of Safety

joseph.cheung@dot.gov

Joey Riddle, Safety Engineer

South Carolina DOT 

RiddleJD@scdot.gov

FOR MORE INFORMATION

Citing a before and after study of seven HFST project locations, SCDOT experienced an 

81 percent reduction in wet crashes and 71 percent reduction in total crashes. Since HFST 

has proven to be a very cost-effective safety countermeasure, SCDOT has installed 20 HFST 

projects, with approximately 20 more locations planned for 2015. Widespread deployment will 

be incorporated once the DOT identifies the horizontal curves throughout the State. The benefit/

cost analysis for these locations has proven HFST to be a very cost-effective countermeasure.

FHWA-SA-15-056

http://safety.fhwa.dot.gov

Photos: SCDOT