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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter

Safety Eligibility Letter B-141E

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U.S. Department of Transportation
Federal Highway Administration

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

April 8, 2009

In Reply Refer To: HSSD/B-141E

Mr. Brian Smith
Trinity Highway Products, LLC
P.O. Box 568887
Dallas, TX 75356-8887

Dear Mr. Smith:

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

Name of system:Trinity CASS
Type of system:Cable Barrier
Test Level:NCHRP Report 350 TL-3
Testing conducted by:Texas Transportation Institute
Date of request:November 25, 2008
Date of completed package:February 26, 2009

You requested that we find this system acceptable for use on the NHS under the provisions of the 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 “Identifying Acceptable Highway Safety Features” of July 25, 1997, provides further guidance on crash testing requirements of longitudinal barriers.

Description
In our FHWA Acceptance Letters B-119 dated May 13, 2003, and B-119B dated August 28, 2003, we accepted Trinity Highway Products’ 3-cable CASS Cable Safety System with c-channel posts at 2.0m (6’6”), 3.0m (10’0”) and 5.0m (16’5”) post spacing for use on the NHS under the NCHRP Report 350 Test Level 3 (TL-3) criteria.

Your present request is for acceptance of a modified, 4-cable CASS system with c-channel posts. The original 3 cables of the CASS system with c-channel posts remain at the same heights. The modification is the addition of a fourth cable located at a height of 585mm (23”), midway between the bottom and middle cables of the 3-cable CASS system with c-channel posts, and separated by plastic spacers as shown in the enclosed drawings.

You correctly noted that terminating the fourth cable must be properly addressed, and you did so by modifying the NCHRP TL-3 compliant terminal that was accepted in the FHWA letter CC-76 dated July 29, 2002. The modification includes increasing the length of the CASS Cable Terminal through the addition of a fourth Cable Release Post as shown in the enclosed drawing. The fourth cable remains at the 585mm (23”) height on the traffic side of the terminal from Post #9 through Post #4, at which point it begins its descent towards its termination at Cable Release Post #1X.

Findings
Because the spread of the four cables is within the limits of the 3-cable system tested with c-channel posts, we consider this system to be similarly crashworthy. In addition, the modified, 4-cable CASS system with c-channel posts are acceptable for use on the NHS under the NCHRP Report 350 TL-3 conditions at all previously accepted post spacing and embedment types (driven post, post set in driven tube sleeve, and post set in tube sleeve encased in a concrete footing) under the range of conditions tested and discussed above, when such use is acceptable to a highway agency.

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

 

Sincerely yours,

David A. Nicol

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

Page last modified on August 16, 2011.
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