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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter B-227

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U.S. Department of Transportation
Federal Highway Administration

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

January 6, 2012

In Reply Refer To:
HSST/B-227

Dave Olson
Design Policy, Standards, & Research Manager
Washington State Department of Transportation
P.O. Box 47329
Olympia, Washington  98504-7329

Dear Mr. Olson:

This letter is in response to your request for the Federal Highway Administration (FHWA) to review a roadside safety system for eligibility for reimbursement under the Federal-aid highway program. 

Name of system: High Tension 3-cable median and roadside barriers
Type of system: Generic cable barrier system
Test Level: NCHRP Report 350 Test Level 3
Testing conducted by: Texas Transportation Institute
Task Force 13 Designator: SGM01b
Date of request: December 23, 2010
Date initially acknowledged:

January 7, 2011

Date of completed package:

January 7, 2011

Decision:
The following device is eligible, with details provided below:

Based on a review of crash test results submitted by the manufacturer certifying the device described herein meets the crashworthiness criteria of the National Cooperative Highway Research Program (NCHRP) Report 350, the device is eligible for reimbursement under the Federal-aid highway program.  Eligibility for reimbursement under the Federal-aid highway program does not establish approval or endorsement by the FHWA for any particular purpose or use.

The FHWA, the Department of Transportation, and the United States Government do not endorse products or services and the issuance of a reimbursement eligibility letter is not an endorsement of any product or service.

Requirements
Roadside safety devices should meet the guidelines contained in the NCHRP Report 350 or the American Association of State Highway and Transportation Officials' Manual for Assessing Safety Hardware (MASH).   The FHWA Memorandum “Identifying Acceptable Highway Safety Features" of July 25, 1997 provides further guidance on crash testing requirements of longitudinal barriers.

Description
The purpose of this test program was to develop a generic, high-tension 3-cable roadside and median barrier using the same length-of-need design as the current low-tension generic cable systems.  The 476-foot long test installation consisted of a 336 ft length modified Weak-Steel Post Wire Rope Guardrail System SGR01a-b with posts spaced at 16 feet.  A high-tension terminal anchored each end.  Wire rope heights are the same as detailed in the SGR01a-b specification.  The system was terminated with Trinity terminals that utilize wire rope Controlled Release Posts (CRP). Standard 3x7 non-prestretched wire ropes were used to match field applications of the system. A splice connection was placed in the second clear span downstream of first contact with the test vehicle.

A Crosby 3/4-inch G-416 epoxy socket was used for termination of each wire rope.  The epoxy socket termination performed as well as the field swage termination; however, this termination presented a higher risk of an unsuccessful full-scale test due to snagging at the termination site. It is expected that if the epoxy socket termination is successful the field swage would also be successful.  Each epoxy socket requires 86 cc. of Crosby Wirelock W416-7 socket compound. A standard Crosby HG-226 1-inch x 12-inch eye and eye turnbuckle were used to connect the two epoxy sockets at each splice.  A 1-inch x 6-inch Crosby G-291 eye bolt with double nuts was used to terminate the wire ropes at the CRP. Tension of the wire ropes prior to the full-scale crash test was 5620-5640 lb. 

You asked that field swaged fittings, previously crash tested at TTI on cable barrier systems, would be found eligible.  Dynamic testing of the field swage fitting at Texas Transportation Institute (TTI) indicates that field swaged fittings performed better than the Crosby epoxy socket used in the full scale crash test. We concur that field swaged fittings (such as the Trinity parts 5873 and 5874 included in the TTI evaluation) are eligible as an alternative to the Crosby epoxy sockets. 

Enclosed for reference is the test data summary sheet showing the crash test and results which were in reasonably close conformity with NCHRP Report 350.  The vehicle remained upright and deflected the barrier 10.2 feet. A working width of 11 feet should be used for design purposes.

Findings
The system described above and detailed in the enclosed drawings is eligible for reimbursement and should be installed under the range of conditions tested, when such use is acceptable to a highway agency.

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

 

Sincerely yours,

/* Signature of Michael S. Griffith */

Michael S. Griffith
Director, Office of Safety Technologies
Office of Safety

Enclosures

Page last modified on January 17, 2013.
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