Pilot program aims to ease over-correction problems
Posted March 22, 2011
Benson, N.C. — The North Carolina Department of Transportation is launching a pilot study in Johnston County involving a new paving technique designed to make roadways safer.
The Safety Edge technique adds a 30 degree slope between the edge of the resurfaced road and the unpaved shoulder.
Traditional resurfacing leaves a vertical pavement edge on the shoulder, creating a drop-off. When a driver heads off the road, sometimes the wheel gets caught on the edger of the pavement, causing the driver to over-correct and crash.
DOT safety engineer Shawn Troy said drivers aren’t prepared for that drop-off.
“I think it’s just because people don’t understand that you need to slow down. It’s a shock,” Troy said Tuesday.
Researchers studying wrecks involving vehicles that ran off the road between 2002 and 2004 found that pavement edges were a contributing factor in 18 percent of rural wrecks on paved roads with unpaved shoulders in Iowa and nearly one-fourth of those crashes in Missouri, according to the U.S. Department of Transportation’s Federal Highway Administration.
Safety Edge is designed to make it easier for drivers to transition between the road and the unpaved shoulder.
“What the Safety Edge does is gives you a little bit of a smooth transition from that run-off-the-road scenario back onto the pavement,” Troy said.
Crews will cover the pavement edge with dirt, but the benefit happens when the dirt is gone.
“Once vehicles run off the road and re-rut out the shoulder, the grass and the dirt, and that edge becomes exposed, that's when the real benefit would come,” Troy said.
NCDOT is part of a federal pilot project to test the Safety Edge method.
Crews are using it on eight Johnston County roads over the next few weeks:
- Technology Drive from N.C. 42 to Glen Road (.29 mile)
- Hospital Road from U.S. 301 to Buffaloe Road (.64 mile);
- Langdon Road from N.C. 50 to Stephenson Road (.94 mile);
- Brogden Road from Richardson Bridge Road to the Wayne County line (2.1 miles);
- Camelia Road from U.S. 301 to Raleigh Road (1.61 miles);
- Shade Tree Road from Raleigh Road to Federal Road (1.58 miles);
- Glen Road from N.C. 42 to the first pavement joint (.39 mile); and
- Country Club Road from U.S. 301 to the end of the state-maintained road (.75 mile).
The DOT also plans to use it on repaving jobs in Harnett and Robeson counties.
“It doesn’t mean that it’s going to prevent a crash, but it’s all about giving that driver the opportunity to get back on the road safely,” Troy said.
Since 2008, the Safety Edge technique has been used on stretches of four roadways—one each in Burke, Iredell, Johnston and Union counties—ranging in length from less than 2 miles to nearly 9 miles. The existing Johnston County installation is along 1.8 miles of Old U.S. Highway 70 West in Clayton from Shotwell Road to the Wake County line.
The Safety Edge system doesn't cost much more than traditional vertical pavement edges, according to the Federal Highway Administration.