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Data shows high-friction pavement treatment improves safety on I-380 Cedar Rapids


Zero LogoEvery day, more than 31,000 vehicles navigate the S-curve on Interstate 380 in Cedar Rapids. A 2008 safety audit investigated potential safety solutions for the many serious crashes on the S-curve through downtown. From May 1, 2007, to April 30, 2012, there were 54 crashes causing 28 injuries and $980,000 in damage. To address the issue, the Iowa DOT, along with our Federal Highway Administration partner, placed a new pavement treatment on the road in the summer 2012.

The treatment adds a layer of epoxy topped with a sharp aggregate to increase the friction between vehicle tires and the road surface, assisting the tire to better grip the road.

“We think it’s working well,” said Cathy Cutler, Iowa DOT transportation planner. “The crash statistics show that both the number and severity of crashes have been reduced since the high-friction surface treatment was installed.” I-380-curve

The cost of the Cedar Rapids project cost was $494,000 for 1.8 miles of roadway.This included 0.3 miles over six lanes. Nearly 80 percent of the cost of the project was for materials. Because this was a safety project in cooperation with FHWA, they chipped in $50,000 for the project.

In addition to the mainline lanes on I-380, the treatment was also used on three ramps at the east mixmaster in Des Moines where interstates 35, 80, and 235 converge.  Post-project crash data from those locations is not yet available.

Iowa DOT safety engineers are looking at other areas where the treatment might be beneficial. Steve Gent, director of the Office of Traffic and Safety, said, “Moving forward, we would potentially place the product where we have a pavement that measures low in friction (generally a polished pavement) and an associated high number of crashes related to the low-friction surface.”

Gent continued, “This is not an inexpensive option, and using it in the right situation could save lives. That’s always our goal with any safety project.”



Annual average before new surface treatment

Annual average after new surface treatment










Property damage



Lost control/Speed too fast/Evasive



Roadway surface contributing


0.7 (work zone)

Wet roadway







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Iowa highway in the evening