The safety edge is a simple, practical and cost-effect safety measure that addresses pavement edge drop-offs. Current research indicates that vertical interfaces between pavement edges and shoulder material become hazardous when a driver drifts off the road. These steep inclines can lead to “tire scrubbing” which can result in over-steering and ultimately, fatal collisions.
Photo source: AAA Foundation for Highway Safety
This is a typical diagram for a crash caused by tire scrubbing. The vehicle at left scrubbed the edge of the pavement, and when it returned, the driver overcorrected, lost control, crossed into the adjacent lane, and struck an oncoming vehicle.
The Safety edge resolves this issue by tapering pavement at a 30˚- 35˚ angle from the horizontal to newly graded material. It can be applied during any normal project and uses <1% of additional asphaltic material.
Photo source: FHWA
Benefits of the safety edge:
- Improves pavement density at edge
- Stronger interface between pavement and graded material
- Less raveling at pavement edge
- Eliminates "tire scrubbing"
- Increased durability and longevity of pavement
- Reduces tort law liability
Information and resources
- MnDOT tech memo 16-01-T-01
- MnDOT Safety Edge tech memo was recently retired and transferred to the Traffic Engineering Manual Chapter 11 - Traffic Safety (PDF) under section 11-8.02 Safety Edges.
- The safety edge - a pavement edge drop-off treatment (PDF)
- Safety edge specifications (PDF)