WASHINGTON — Crashes involving trucks and cars travelling on roads with pavement edge drop-offs are far more likely to result in severe injuries, says a U.S. traffic research group.

A recent study sponsored by the AAA Foundation for Traffic Safety says accidents on such roadways are relatively infrequent, but are more than twice as likely to be fatal when they do occur.

Characterized by a shoulder that is lower than the edge of the paved road surface, pavement edge drop-off can be caused by pavement breaking, erosion and wear of unpaved shoulders, inadequate maintenance, or resurfacing projects that neglect to keep shoulders level with the paved road surface.

Although they can occur on any roadway, they are more common on rural two-lane roads with narrow lanes and shoulders. “A driver may be forced off the road or drive off the road for any number of reasons and pavement edge drop-off, especially if 2 inches or deeper, can increase the risk of a crash and make it difficult for a driver to return to the road safely,” says the group.

A study recommends 2 ft paved shoulders as well as a safety
edge on resurfacing work to reduce severity of crashes

Based on the analysis of crash data, the AAA Foundation report recommends that transportation agencies adopt a policy requiring routine comprehensive sampling of pavement edge drop-off on their roads, and prompt remediation of any pavement edge drop-off of depth meeting or exceeding a prescribed threshold, which should be no higher than 2 inches.

“No national standards exist that indicate the level at which pavement edge drop-off should be addressed,” says the study’s author. “And, construction and maintenance practices related to this problem vary considerably across the country.”

The report also recommends agencies adopt a policy of providing paved shoulders, with a minimum width of 2 feet — or wider if conditions warrant — wherever practical, as well as using a safety edge on resurfacing projects to help eliminate edge drop-offs.

“The safety edge is a low-cost construction technique that has the potential to save lives,” said John Baxter, director of the FHWA’s Office of Safety Design.

Based on an earlier study by the AAA Foundation, the new study was conducted by the Iowa State University Center for Research and Education and Midwest Research Institute.

To promote safe driving when encountering a steep drop-off, the AAA Foundation developed “Over the Edge and Back: What to do if you drop off the pavement edge” — a brochure that explains what drivers should do, and what they should avoid doing, if they drive off the road.

“It’s not about returning to the road quickly, it’s about returning to the road safely, according to Peter Kissinger, AAA Foundation president and CEO. “Don’t panic or immediately attempt to steer back on the road, especially at high speed, as this can easily cause you to lose control of your vehicle.”