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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter B-183

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U.S. Department of Transportation
Federal Highway Administration

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

In Reply Refer To: HSSD/B-183

Mr. Rick Mauer
Outside National Sales Representative
Nucor Steel Marion Inc.
P.O. Box 837
Greenland, NH 03840

Dear Mr. Mauer:

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

Name of system: Nu-Cable Systems – Use of Plastic or Steel Sockets
Use of driven steel sockets
Type of system: Cable Barrier
Test Level: NCHRP Report 350 TL-3 and TL-4
Testing conducted by: Holmes Solutions of New Zealand and
Texas Transportation Institute
Date of request: July 25, 2006

You requested that we find these modified systems 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. The FHWA Memorandum “Action: Identifying Acceptable Highway Safety Features” of July 25, 1997, provides further guidance on crash testing requirements of longitudinal barriers.

Description
The Nu-Cable barrier systems consist of three or four steel cables mounted on 4 lb/ft Nucor Steel Marion Rib-Bak u-channel posts. These systems were found acceptable in the following FHWA acceptance letters:

B-96 August 30, 2002 3-strand roadside or median barrier
B-96A October 12, 2005 Alternative post and foundation designs
B-167 February 24, 2008 4-strand Nucor Wire Rope Barrier System TL-4

Crash Testing
All test level 3 (TL-3) and TL-4 barriers were tested in either plastic socket sleeves (New Zealand tests) or steel socket sleeves (Texas tests) encased in a rebar fortified concrete foundation. No difference in performance was noted between the two types of sleeves. Your request is to allow the interchangeability of the two foundation systems on your Nu-Cable systems. We concur in this request for new installations. When barrier installations are damaged to the degree that the post foundations are affected, repairs should be made using the same foundation systems they were tested with to the extent practicable.

You also requested the use of driven steel socket sleeves for 4-pound-per-foot u-channel posts, as shown in the enclosed drawing. Informal vehicle testing in standard soil showed no perceptible movement of the socket.

Findings
The following Nu-Cable System modifications acceptable for use on the NHS under the range of conditions tested, when such use is acceptable to a highway agency:

1) Posts mounted in plastic socket sleeves encased in a rebar fortified concrete foundation,
2) Posts mounted in steel socket sleeves encased in a rebar fortified concrete foundation,
3) Posts mounted in driven socket sleeves with soil plates.

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

 

Sincerely yours,

Signature of David A. Nicol
David A. Nicol
Director, Office of Safety Design
Office of Safety

Enclosures


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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