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Pavement Edge Drop-Offs

    Each year, an estimated 11,000 drivers are injured and 160 die in the US in crashes related to pavement edges. Tort liability claims resulting from pavement edge drop-offs cost highway agencies millions each year.

What are Edge Drop-Offs? How do they Develop?

    A drop-off occurs when there is a difference in height between a roadway's paved surface and the adjacent shoulder or ground. The pavement edge is unsafe when the angle is nearly a 90-degrees and the drop-off is more than 2 to 5 inches. Drop-offs occur due to:

    When tires slip off a paved surface onto an unimproved or deteriorated shoulder, drivers will attempt to steer back onto the roadway and may lose control of their vehicles. The pavement edge "scrubs" the tires so drivers over-steer. Over-steering results in drivers re-entering the roadway at a sharp angle and losing control of their vehicle. Their right rear tire may catch the pavement edge and swing the car around or sideways causing the car to veer into the adjacent lane. This may result in a collision with oncoming cars or running off the road and striking a fixed object.
    The solutions to repair severe edge drop-offs are simple:

What's A Safety Edge?
    A safety edge is installed at the edge of the road in reconstruction and resurfacing projects. It is a simple and cost-effective way to create a safer road edge. The edge creates a small "ramp" from the shoulder to the new pavement allowing errant vehicles to "climb" back onto the pavement in a controlled way. Asphalt pavement contractors use a special edging device to install a safety edge while resurfacing.
    The safety edge also creates a strong tie between roadway and shoulder by locking the old shoulder into the resurfaced road. If time and money prevent immediate resurfacing or rebuilding of shoulders, crews can restore the shoulders at a later time when the edge is used. If plans exist to rebuild the shoulders immediately the safety edge is still a good idea. If the rebuilt shoulder washes out, the safety edge will remain to assist errant vehicles back to the pavement.

Distance from Edge of Travel Lane

Dropoff Height

 

2 inches

 

 2 inches to ≤ 4 inches

 

> 4 inches to ≤ 2 feet

 

> 2 feet

≤ 4 feet

No channelizing devices required.

Install 1:1 or flatter safety edge. (1). (2). (3)

·     Place suitable material to grade and compact to non-movement.

·     Install a 1:3 (3:1) slope with suitable material and compact to non-movement. (1). (2). (3)

·     Install temporary barrier.

·     Install temporary barrier

·     Place suitable material to grade and compact to non-movement.

·     Install a 1:3 (3:1) slope with suitable material and compact to non-movement. (1). (2). (3)

> 4 feet to ≤12 feet

No channelizing devices required.

Install 1:1 or flatter safety edge.  (2).

·     Place suitable material to grade and compact to non-movement.

·     Install a 1:3 (3:1) slope with suitable material and compact to non-movement. (2). (3)

·     Install temporary barrier

·     Place suitable material to grade and compact to non-movement.

·     Install a 1:3 (3:1) slope with suitable material and compact to non-movement. (2). (3)

> 12 feet to ≤15 feet

No channelizing devices required.

Use channeliz­ing devices throughout dropoff condi­tion. (3)

Use channelizing devices throughout dropoff condition. (3)

Use channelizing devices throughout dropoff condition. (3)
 

Footnotes:

  1. Install low shoulder signs at intervals not to exceed ˝ mile throughout the dropoff condition.
  2.  Use channelizing devices throughout dropoff condition.
  3. No channelizing devices are needed if the dropoff is:

Kistic, Joseph, Remedy of Pavement Edge Drop-Offs from Resurfacing Projects, The Pennsylvania Local Roads Program, LTAP Technical Information Sheet #123, Fall 2005

The Safety Edge, Federal Highway Administration, Washington, D.C., FHWA-SA-05-003. accessed August 11,2005, at http://safety.fhwa.dot.gov/roadway_depUdocs/sa05003.pdf

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