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                Safety Eligibility Letter B-137D
  
  **Hardware Type:**
            Longitudinal Barriers and Bridge Rails
                          **Code:**
            B-137D
                          **Date:**
            02/08/2008
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            Gibraltar
                          **Device Description:**
            Four point anchorage to 4 cable barrier
                          **View PDF:**
            b137d.pdf (488.86 KB)
    
    HSSD/B-137D



DOT logo
U.S. Department of Transportation
**Federal Highway Administration**
400 Seventh St., S.W.
Washington, D.C.  20590February 8, 2008
In Reply Refer To: HSSD/B-137D

Mr. Bill Neusch 
President
Gibraltar
320 Southland Road
Burnet, TX 78611
	
Dear Mr. Neusch: 
  Thank you for your letter of  October 19, 2007, requesting a modification to the anchorage of your company’s  4-cable barrier. Your original test  level 4 (TL-4) Gibraltar cable barrier was formally accepted for use on the  National Highway System (NHS) in the September 9, 2005, Federal Highway  Administration (FHWA) acceptance letter B-137A. The tested design, as described in that  letter, consisted of cables placed 20 inches, 30 inches, and 39 inches above  the ground line.
In our October 27, 2006, letter  B-137A1 we accepted your 4-cable design having the lower three cables at the  same heights as your TL-3 design while retaining the top cable at the tested  TL-4 height of 39 inches. The addition  of the fourth cable required a modified "hairpin" and lock plate to  retain the cables at the proper heights. In order to "anchor" the added cable  you tapered that 25-inch high cable down to the bottom (20-inch) cable between  the first line post and the last terminal post and connected the two cables  with a series of four cable clamps. Because  of concerns raised over this splicing treatment, especially on downstream  terminals, you have proposed to anchor each of the four cables separately.
The modified anchor is shown on  the enclosed drawings for reference and features the fourth cable attached  directly to the anchor post foundation plate instead of being cable clamped to  the bottom cable. You also added a  fourth J-bolt to each terminal post to accommodate the fourth cable. We concur in this modification and find it  acceptable for use with your four-cable barrier.
The  modified Gibraltar Cable Barrier as described above remains a National  Cooperative Highway Research Program (NCHRP) Report 350 TL-4 median barrier  when the posts are set on alternate sides of the cables or a TL-4 roadside  barrier when the cables are all on the traffic side of the C-posts.
Although the barrier performed well under ideal test impact  conditions when originally crash tested, the likelihood of passenger car  underrides of any cable system****may  increase as the post spacing increases, particularly when the barrier is  installed on non-level or slightly irregular terrain and the cables are not  restrained from lifting at each post.  Consequently, some transportation agencies have limited post spacing to  approximately 6m (20 feet) for cable 
  barriers. The dynamic  deflection of the barrier is likely to increase when it is installed along the  convex sides of horizontal curves, and when distances between anchorages exceed  the 350-foot test length.
Please note the following standard provisions that apply to  the FHWA letters of acceptance:
This acceptance is limited to the  crashworthiness characteristics of the device(s).
  Any changes that may adversely influence the  crashworthiness of the device will require a new acceptance letter.
  Should the FHWA discover that the qualification  testing was flawed, that in-service performance reveals unacceptable safety  problems, or that the device being marketed is significantly different from the  version that was crash tested, it reserves the right to modify or revoke its  acceptance.
  You will be expected to supply potential users  with sufficient information on design and installation requirements to ensure  proper performance.
  You will be expected to certify to potential users  that the hardware furnished has essentially the same chemistry, mechanical  properties, and geometry as that submitted for acceptance, and that they will  meet the crashworthiness requirements of the FHWA and the NCHRP Report 350.
  To prevent misunderstanding by others, this  letter of acceptance, designated as number B-137C, shall not be reproduced  except in full. This letter, and the  test documentation upon which this letter is based, is public information. All such letters and documentation may be reviewed  at our office upon request.
  The four-cable Gibraltar Cable Barrier System is  a patented product and considered proprietary.  If proprietary devices are specified by a highway agency for use on  Federal-aid projects, except exempt, non-NHS projects, they: (a) must be  supplied through competitive bidding with equally suitable unpatented items;  (b) the highway agency must certify that they are essential for synchronization  with the existing highway facilities or that no equally suitable alternative  exists; or (c) they must be used for research or for a distinctive type of  construction on relatively short sections of road for experimental  purposes. Our regulations concerning  proprietary products are contained in Title 23, Code of Federal Regulations,  Section 635.411.
  This acceptance letter shall not be construed as  authorization or consent by the FHWA to use, manufacture, or sell any patented  device for which the applicant is not the patent holder. The acceptance letter is limited to the  crashworthiness characteristics of the candidate device, and the FHWA is  neither prepared nor required to become involved in issues concerning patent  law. Patent issues, if any, are to be  resolved by the applicant.Sincerely yours,
        Signature of David A. Nicol
      David A. Nicol, P.E. 
Director, Office of Safety  Design
Office of SafetyEnclosures U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

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