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Safety Edge

The asphalt paving technique called the Safety Edge is gaining momentum across the country as State and local transportation departments strive to protect motorists from run-off-the-road crashes. The Federal Highway Administration recommends that agencies use the safety edge technique—particularly on two-lane roads with unpaved shoulders.

Street paving machineDuring the normal paving process, pavement edges are formed vertical or near vertical. The recommended practice of bringing the adjacent graded material (unpaved shoulder or stabilized soil) flush with the top of the pavement only lasts for a short time and requires frequent maintenance. The exposed vertical edge can contribute to drivers losing control of the vehicle when attempting to recover from a roadway departure.

While data documenting the role of pavement edges at the national level remain elusive, studies in several States point to the life-saving potential of safer edges. For example, researchers studying crashes in Missouri during 2002-2004 reported that pavement edges may have been a contributing factor in as many as 25 percent of rural run-off-road crashes on paved roadways with unpaved shoulders. This type of crash was twice as likely to include a fatality as rural crashes overall on similar roads.

Recent updated research has shown that almost all drivers and vehicles can recover if the edge is tapered to 30 degrees from the horizontal. This durable taper, the Safety Edge, is easy to include in the paving process, provides a safer roadway edge, and a stronger interface between the pavement and the graded material. The additional cost of the asphalt edge is minimal when included as part of resurfacing projects. Benefits include the avoided economic and social impacts of fatalities, injuries, property damage, and increases pavemnet durability.

Diagram shows cutaway of roadway. Atop the existing base or pavement is a new asphalt overlay surface. The edge of the new asphalt overlay does not drop off, but is cut into a wedge shape at a 30° to 35° angle. Graphic source: J. Pitzer.


Page last modified on May 18, 2012.
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