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          For More Info Visit the Office of Safety's SafetyEdgeSM website

              SafetyEdgeSM
U.S. Department of Transportation logoU.S. Department of Transportation
    Federal Highway Administration
    FHWA-SA-21-038

          PDFSafetyEdge_508.pdf (PDF, 441.8 KB)


        The SafetyEdgeSM technology shapes the edge of the pavement at approximately 30 degrees from the pavement cross slope during the paving process. This safety practice eliminates the potential for vertical drop-off at the pavement edge, has minimal effect on project cost, and can improve pavement durability by reducing edge raveling of asphalt.

Rural road crashes involving edge drop-offs are 2-4 times more likely to include a fatality than other crashes on similar roads.1 Vehicles may leave the roadway for various reasons ranging from distracted driver errors to low visibility, or to the presence of an animal on the road. Exposed vertical pavement edges can cause vehicles to become unstable and prevent their safe return to the roadway. The SafetyEdgeSM gives drivers the opportunity to return to their travel lane while maintaining control of their vehicle.

The SafetyEdgeSM technology only requires adding one of several commercially available devices to the screed or endgate when placing hot-mix asphalt. Forms for shaping the edge of concrete pavement are simpler and can be made on site by the contractor. Some agencies allow the SafetyEdgeSM to remain exposed while a segment is under construction, unlike conventional pavement edges. However, before construction ends, agencies should bring the adjacent roadside flush with the top of the pavement for both the SafetyEdgeSM and traditional pavement edge. Over time, regardless of the edge type, the edge may become exposed due to settling, erosion, and tire wear. When this occurs, the gentle slope provided by the SafetyEdgeSM is preferred versus the traditional vertical pavement edge.

Transportation agencies should develop standards for implementing the SafetyEdgeSM systemwide on all new asphalt paving and resurfacing projects where curbs and/or guardrail are not present, while also encouraging standard application for concrete pavements.

"Illustration: This cross-section diagram describes the pavement structure after an overlay with SafetyEdge is applied. At the bottom of the cross-section diagram is the base material. Above the base is the old pavement and old graded shoulder. Some of the old graded shoulder has worn away, revealing the 90-degree edge of the old pavement. Above the old pavement is the new overlay with SafetyEdge. This overlay overlaps with the old graded shoulder and tapers off at a 30-degree angle to the horizontal. Finally, the new graded shoulder is located adjacent to the new overlay."

**Cross-section view of an overlay with the SafetyEdgeSM**.

Source: FHWA-SA-17-044



        Sources
        1. Hallmark et al. Safety Impacts of Pavement Edge Drop-offs, (Washington, DC: AAA Foundation for Traffic Safety: 2006), p 93.

2. (CMF ID: 9205, 9211, 9217) Donnell et al. Development of Crash Modification Factors for the Application of the SafetyEdgeSM on Two-Lane Rural Roads. FHWA-HRT-17-081, (2017).

3. Safety Effects of the SafetyEdgeSM, FHWA-SA-17-044, (2017).
    
    Safety Benefit IconSafety Benefits:
              
11%
      
            reduction in fatal and injury crashes.2
          21%
      
            reduction in run-off road crashes.2
          19%
      
            reduction in head-on crashes.2
          Benefit-Cost Ratio Range3
          700:1 to 1,500:1
      
            "The angle of SafetyEdge relative to the roadway surface. A person holds a level perpendicular to the edge of the roadway. There is no backfill material adjacent to the paved surface, revealing the SafetyEdge below. The SafetyEdge consists of a slope of asphalt installed at approximately a 30-degree angle to the horizontal."**Example of the SafetyEdgeSM after backfill material settles or erodes.**

Source: FHWA U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

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