Safety Edge: Cost Effective Way to Reduce Roadway Crashes

The Federal Highway Administration is recommending states implement a paving technique called the safety edge to reduce run-off-the-road crashes. This type of accident accounts for 53 percent of all fatal crashes.

The Safety Edge

Without the safety edge, roadways with unpaved shoulders are paved with a vertical edge against the soil. When a road is first paved, the shoulder material is built up to be flush with the pavement. For the shoulder to remain flush with the pavement frequent maintenance is required. Over time, a vertical drop off from pavement to shoulder develops.

The FHWA recommends a 30 degree sloped pavement edge to eliminate the vertical pavement drop-off.

The Dangers of Vertical Pavement Drop-Offs

It can be dangerous for drivers when the shoulder is not flush with the pavement and a resulting drop-off occurs. When a driver veers off a roadway and tries to steer back onto the pavement, the tire may be blocked by the vertical edge, an effect known as "tire-scrubbing". This can cause over-steering, which, when back onto the pavement, can cause drivers to veer into oncoming traffic or adjacent lanes.

The AAA Foundation conducted a study in 2006 analyzing pavement regulations and crash statistics in 10 states and British Columbia. The study states that from 2002 to 2004, un-safe pavement edges may have contributed to 25% of rural run-off-the-road crashes on paved roads with unpaved shoulders in Missouri. In the same time frame, pavement edges may have contributed to 18% of rural run-off-the-road crashes in Iowa.

The Texas Department of Transportation reports 1,210 fatal crashes on highways, where shoulders are often unpaved. This is over two times higher than reported fatal crashes on any other type of roadway in Texas.

Benefits of the Safety Edge

The safety edge is proven to reduce crashes and is becoming popular nationwide. There is minimal additional effort required to implement the safety edge. It can be included into any resurfacing project for less than 1 percent of the budget. The safety edge is also proven to improve the durability of the pavement and to extend service life.

FHWA pavement engineer Chris Wagner states, "We believe the safety edge is a focused solution that will reduce fatalities on rural two-lane roads where run-off-the-road crashes are most prevalent."