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                Safety Eligibility Letter B-137C (HSSD)
  
  **Hardware Type:**
            Longitudinal Barriers and Bridge Rails
                          **Code:**
            B-137C (HSSD)
                          **Date:**
            01/08/2008
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            Gibraltar
                          **Device Description:**
            Revised anchor design (4 archors)
                          **View PDF:**
            b137c_hssd.pdf (484.28 KB)
    
    Safety Eligibility Letter B-137C (HSSD)

			 
			**Download Version**PDF [563 KB]
			
			DOT logoU.S. Department of Transportation**Federal Highway Administration**
			1200 New Jersey Ave. S.E.Washington, D.C. 20590
			February 8, 2008
			In Reply Refer To: HSSD/B-137C
			
			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
							Director, Office of Safety Design
							Office of Safety U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

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