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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter B-171

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U.S. Department of Transportation
Federal Highway Administration

1200 New Jersey Ave. S.E.
Washington, D.C. 20590

April 16, 2008

In Reply Refer To: HSSD/B-171

Tim Aschenbrenner, P.E.
Project Development Branch Manager
Colorado Department of Transportation
4201 East Arkansas Avenue
Denver, CO 80222-3400

Dear Mr. Aschenbrenner:

This letter is in response to your request for Federal Highway Administration (FHWA) acceptance of a roadside safety system for use on the National Highway System (NHS).

You requested that we find this system acceptable for use on the NHS under the provisions of National Cooperative Highway Research Program (NCHRP) Report 350 “Recommended Procedures for the Safety Performance Evaluation of Highway Features.”

Requirements
Roadside safety systems should meet the guidelines contained in the NCHRP Report 350, "Recommended Procedures for the Safety Performance Evaluation of Highway Features". FHWA Memorandum “ACTION: Identifying Acceptable Highway Safety Features” of July 25, 1997, provides further guidance on crash testing requirements of longitudinal barriers.

Description
The Colorado portable concrete barrier is a modification of the Oregon barrier covered in FHWA acceptance letter B-86 dated August 17, 2001. Drawings of the Colorado barrier, the Oregon barrier, and a comparison of the two shapes are enclosed for reference. Here is a brief description of the Colorado barrier:

Each 12-foot, 6-inch long barrier segment is reinforced longitudinally with eight #5 bars. The barrier is 34 inches tall, 23 inches wide at the base, and 8 inches wide at the top. The distance from the ground to the slope break point is 11 inches which is 1 inch higher than the standard “F” shape and 2 inches lower than the New Jersey shape.

The pin and loop connection consists of two 3/4-inch A36 steel loops near the top of one segment end, above a single 3/4-inch steel loop near the bottom on the same end. The corresponding loops on the adjacent barrier segment consisted of a single loop near the top and double loops on the bottom. When placed together, the single loops fit between the double loops, forming two connection points, each consisting of three loops. A one-inch diameter, 29-inch long ASTM A449 steel pin, with no nut or retention device, is dropped through the loops to complete the connection.

Crash Testing
The Oregon barrier was tested by KARCO Engineering and had a deflection of 30 inches. The modified Colorado barrier is approximately 5 percent lighter, a factor which should have no significant effect on the crashworthiness of the barrier system.

Findings
We concur that the Colorado portable concrete barrier system is comparable to the Oregon barrier that was previously accepted and is acceptable for use on the NHS as a TL-3 barrier when allowed by the highway agency.

Please note the following standard provisions that apply to FHWA letters of acceptance:

 

Sincerely yours,

George E. Rice, Jr.

for David A. Nicol, P.E.
Director, Office of Safety Design
Office of Safety

Enclosures

Page last modified on June 24, 2011.
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Federal Highway Administration | 1200 New Jersey Avenue, SE | Washington, DC 20590 | 202-366-4000