Roads wind through the Ouachita, Winding Stair and Kiamichi Mountains in LeFlore County, where ODOT Division Two Engineer Anthony Echelle and his team strive to reduce the number of collisions, injuries and fatalities. In 2016, the Oklahoma Highway Safety Office recorded 15 fatal crashes in the county.
Oklahoma locations where HFST will be applied in Fall 2018.
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"We're always ready to bring in anything that will further enhance safety. We have lots of curvy roads and places where using a treatment like HFST can make a difference," said Echelle, who is keen to begin the safety enhancements this fall.
The curve safety project will allow ODOT to install curve advisory signs, LED blinking lights, lowered-speed limit signs, guard rails and HFST along a stretch of US-259 that passes through the Kiamichi Mountains. The project will also benefit drivers in Sequoyah County.
"We've been concerned by the crashes on SH-82 north of the SH-82 and SH-100 junction in Sequoyah County," said ODOT Division One Traffic Engineer Justin Calvarese. "We’re hoping that the HFST provides additional traction so that drivers are less likely to crash at that location."
What is HFST?
High Friction Surface Treatments are pavement-surfacing systems with exceptional skid resistant properties not typically provided by conventional materials. In spots where extra friction is needed, such as steep grades, sharp curves or places that see heavy braking, an epoxy-resin binds a layer of the rough mineral aggregate calcined bauxite to the roadway surface. The treatment creates a durable surface that retains its grip and skid-resistant properties for up to eight years on Oklahoma roads.
The technology was brought to Oklahoma by the State Innovation Council (STIC), a task force that meets quarterly to bring together transportation stakeholders to evaluate innovations and spearhead their deployment in the state. Innovation council members learned of HFST through the Federal Highway Administration (FHWA) Every Day Counts (EDC) program, which encourages deployment of innovative underutilized innovations that shorten project delivery, enhance roadway safety, reduce traffic congestion and improve environmental sustainability.
"Oklahoma's innovation council is a unique opportunity for representatives from transportation agencies, industry and academia to collaborate and pursue innovations that will help deliver a modern and efficient transportation system in our state," said ODOT Director of Capital Programs and STIC Chair Dawn Sullivan.
High Friction Surface Treatment (HFST) in Oklahoma
Oklahoma began using HFST in 2013, when members of the STIC saw an opportunity to address a particularly challenging stretch of roadway on a horizontal curve in northeast Oklahoma with this cost-effective treatment.
“We did a system-wide screening to see where this technology really made sense. A rural two-lane highway near Salina, where we were observing high speeds and run-off-the road crashes, fit the criteria,” said ODOT Traffic Safety Manager David Glabas. “ODOT Division Eight had done everything they could to improve the safety of the highway, including adding rumble strips and oversized chevron signs. During the HFST application process, the neighbors were showing up and thanking us."
“Before high friction surface treatment was applied, we were seeing a high rate of crashes occurring on SH-20 in Mayes County, especially in wet conditions,” noted ODOT Division Eight Maintenance Engineer Trapper Parks.
Two of the original three sites on SH-20 in Mayes County are slated for re-application under the new curve safety plan, which is consistent with anticipated treatment life.
An Oklahoma Success Story By the Numbers
After applying HFST to three curves in Mayes County in 2011-2013, ODOT applied HFST on three high volume roadway sections of I-40 and I-44 in the Oklahoma City metropolitan area in 2015.
As of June 2018, HFST has been applied and reducing crashes at locations in Oklahoma and Mayes counties.
To measure the performance and lifespan of HFST on Oklahoma roads, ODOT Field Services Manager Bryan Cooper conducted visual monitoring of pavement condition at all six HFST sites. Cooper analyzed ODOT skid-friction data and collaborated with Oklahoma State University (OSU) professors Kelvin Wang and Qiang Joshua Li to secure grip data on the sites.