U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Avenue, SE
Washington, DC 20590
202-366-4000
U.S. Department of Transportation
Federal Highway Administration
1200 New Jersey Ave. S.E.
Washington, D.C. 20590
November 5, 2007
In Reply Refer To: HSSD/CC-102
Mr. Owen Denman, PE
President, Barrier Systems Inc.
180 River Road
Rio Vista, CA 94571-1208
Dear Mr. Denman:
Thank you for your letter of August 2, 2007, requesting the Federal Highway Administration (FHWA) acceptance of tangent, flared, and median versions of the X-Tension™ Technology End Terminals for use on the National Highway System (NHS). The original system, the X-350™ Guardrail Terminal was developed by Armorflex, Ltd., and accepted by FHWA in our July 9, 2005, letter CC-91. Barrier Systems, Inc. has since acquired the rights to use the X-350™ Guardrail technology and has developed it further. Accompanying your letter were reports of crash testing conducted by Holmes Solutions, an approved test laboratory which was formerly a facility of the University of Canterbury in Christchurch, New Zealand, and DVD video of the tests. You requested that we find the terminals 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."
Introduction
The FHWA guidance on crash testing of roadside safety hardware is contained in a
memorandum dated July 25, 1997, titled "INFORMATION: Identifying Acceptable Highway
Safety Features." The original Armorflex X350 tangent terminal for use with strong-post
W-beam guardrail includes an impact head through which two anchor cables are threaded,
breakaway line posts, a slider/slider bracket assembly, a cable anchor bracket, and a foundation
anchor. For side impacts to the rail, tension is transferred via the cables to the foundation anchor
to provide containment and redirection. For head-on and angled impacts directly at the end,
friction between the cables and a convolution in the impact head dissipates crash energy. The
slider/slider bracket assembly allows the first W-beam rail segment to slide back along the
second segment and away from the impacting vehicle.
Your present request is for: 1) modifications to the original tangent version, 2) a flared version, and 3) a median version, using the name X-Tension™ Technology Guardrail End Terminals. The enclosed chart "National Cooperative Highway Research Program Report 350 Test Matrix – X-Tension Testing Program" details the original matrix of tests used to validate the Armorflex X350 design, a Test Requirement Analysis of the needed impacts to validate the Flared Offset Configuration and the Median Terminal, and a Component Modification Analysis.
Testing
You discussed the proposed test matrix with Mr. Nicholas Artimovich of my staff and reached
agreement on the tests detailed in the enclosed testing program chart mentioned above. The
following tests were conducted and the test data summary sheets are enclosed for reference:
We concur that these tests are satisfactory to show NCHRP Report 350 compliance with the following:
Findings
The results of the testing met the FHWA requirements and, therefore, the devices described in
the various requests above and detailed in the enclosed drawings are acceptable for use on the
NHS under the range of conditions tested, when proposed by a highway agency.
Please note the following standard provisions that apply to the FHWA letters of acceptance:
Sincerely yours, /* Signature of George E. Rice*/
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Enclosures