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FHWA Highway Safety Programs

Raised Pavement Markers (RPMs) – A Low-Cost Alternative for Run-off-the-Road Crashes

Publication Year:

Original publication: 2013 National Roadway Safety Awards Noteworthy Practices Guide; FHWA-SA-14-002; 2013

"Two photographs of a curve with 20 feet RPM spacing, one during the day and one at night. The photograph at night shows the markers reflecting light."

Example of 20 feet RPM spacing for a curve.

Example of same location at night.

Describe the roadway safety situation or state before the new practice was implemented. What was the safety issue, problem, or gap?

With help from the Federal Highway Administration (FHWA) and Alabama Department of Transportation (ALDOT), Mobile County, Alabama determined that 10 rural roadways within the county rated the highest in the State for run-off-the-road crashes. These roadways, totaling more than 68 miles, had experienced 224 run-off-the-road type crashes between 2005-2008, resulting in 7 fatalities and 152 injuries.

What were the key challenges that needed to be addressed before the new practice could be implemented?

The challenge was to determine the most effective low-cost treatment. While rumble strips can reduce run-off-the-road crashes, installing them requires large machinery, manpower with technical skills, and oftentimes additional right of way, making them a cost-prohibitive solution.

Describe the new practice:

To counter these cost concerns, Mobile County and ALDOT implemented a program for the systematic application of raised pavement markers (RPM) to improve sight distance recognition and guidance along the edge of the pavement, especially during wet weather conditions at night. One-directional, white RPMs adjacent to the white edge-line stripe were easily installed using existing traffic maintenance department equipment and manpower.

What technical and/or institutional changes resulted from the new practice?

The program set guidelines for consistent implementation for all roadways within the county. RPMs were placed just outside the existing edge-line stripe.

  • Tangent sections of roadways would have RPMs installed at 80 feet spacing.
  • At the approach to a curve having an advance warning curve sign, the spacing would be 40 feet apart from sign location to the beginning of the curve.
  • In the curve, the spacing would be 20 feet until reaching the tangent section.

What benefits were realized as a result of the practice?

Based on 2009-2012 crash data, crashes on the initial 10 roadways treated dropped from 224 to 33, from 7 fatalities to 0, and from 152 injuries to 10. The average number of crashes for all 10 roadways decreased by 85.3 percent. RPMs give critical guidance to drivers, especially along dark and rainy county roadways. As a result of this pilot project, they are now included in most roadway projects in Alabama.

Is the practice you are submitting from a larger report, journal, or other document? Yes

2013 National Roadway Safety Awards Noteworthy Practices Guide
Publication FHWA-SA-14-002

Contact

James Foster
Mobile County Engineer Office
251-574-8595
JFoster@mobilecounty.net