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                Safety Eligibility Letter B-167
  
  **Hardware Type:**
            Longitudinal Barriers and Bridge Rails
                          **Code:**
            B-167
                          **Date:**
            01/24/2008
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            Nucor Steel
                          **Device Description:**
            Four-cable Nucor Wire Rope Barrier System TL-4
                          **View PDF:**
            b167.pdf (368.19 KB)
    
    HSSD/B-167


DOT logo
U.S. Department of Transportation
**Federal Highway Administration**
400 Seventh St., S.W.
Washington, D.C.  20590January 24, 2008
In Reply Refer To:  
HSSD/B-167

Mr. Rick Mauer
Nucor Steel Marion,  Inc.
912 Cheney Avenue
Marion, OH 43302
	
Dear Mr. Mauer:
Thank you for your November 12, 2007, letter requesting the  Federal Highway Administration’s (FHWA) acceptance of the four-cable Nucor Wire  Rope Barrier System as a Test Level 4 device for use on the National Highway  System (NHS). Accompanying your letter  were reports of crash testing conducted by Holmes Solutions of Christchurch,  New Zealand. You requested that we find  this barrier 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 and  Description**
  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 Nucor Wire Rope Barrier System consists of four 19-mm  (3/4-inch) wire rope cables attached directly to 4 pound-per-foot Nucor U-post  sections. The ropes are attached at  heights of 380 mm, 640 mm, and two at 890 mm (15 inch, 25 inch, and 35 inch)  above ground level. The lower two cables  are attached using locking hook bolts which connect directly to the U-posts. The top two cables are supported by a top clip  which engages with the top of the U-post section.
All posts in the Nucor Wire Rope Barrier System are  installed directly into plastic sockets that have been cast into 300 mm (12  inch) diameter concrete foundations. The  posts are spaced at 
  6.1 m (20 foot) centers along the length of the barrier. The overall length of the test installation  was 103.7 m (340 feet) plus an additional 8 m (26 feet) of Armorwire terminal  at either end of the barrier.
The Nucor Wire Rope Barrier System was constructed with the  cable fittings and cable adjustment mechanism staggered along the length of the  barrier, with two fittings upstream and two downstream from the point of  impacts. All of the cable fittings were  located midway between the steel line posts.
The 19 mm diameter 3x7 strand “Galvanized 320, lay – RHRL”  cables were pre-stretched by 
  25 percent and tensioned to 25kN (5600 pound-force) at an  ambient temperature of 21 Celsius (70 Fahrenheit). The barrier was terminated using the  Armorwire Terminal End which was found acceptable in FHWA letter CC-98 dated  April 9, 2007.
The U-posts have different dynamic strength characteristics  in different orientations. In medians,  the posts may be installed in an alternating sequence where each post is  rotated 180 degrees from the previous post. It was considered appropriate to orient all  posts into the strong axis orientation during the crash tests as it was expected  that this orientation makes the posts more prone to failure, thus offering the  least assistance in maintaining the cable height. As such, NCHRP Report 350 Test 4-12 was run  with the posts oriented with the hollow field towards the test vehicle (i.e. in  the strong direction.)
**Testing**
  Full-scale automobile and single-unit truck testing was  conducted on the Nucor Wire Rope Barrier System. Successful testing with the 2000P pickup had  been conducted on the 3-cable system and this optional test was deemed  unnecessary for the validation of the 4-cable barrier. The test details are  summarized in the table below, and the test data summary sheets are enclosed  for reference.
NCHRP 350 #
    Vehicle Mass
    Speed
    Angle
    Deflection*4-10
    904 kg
    100.5 km/hr
    20.1 degrees
    1.40 m4-12
    8050 kg
    84.5 km/hr
    15.0 degrees
    2.29 m* The “design deflection” of a barrier is that recorded  during NCHRP 350 Test 3-11 using the 2000P vehicle. As there has been no test 3-11 on your  four-cable TL-4 system we must rely on a TL-3 test showing a deflection of 2.9  m.
**Findings**
  The four-cable Nucor Wire Rope Barrier System described  above and shown in the enclosed drawings may be used as either a roadside or median  barrier on the NHS under the range of conditions tested when such use is acceptable  to the contracting agency.
Although the barrier performed well under ideal test impact  conditions with the two test vehicles, 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 100m (330-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-167 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 Nucor Wire Rope 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 SafetyEnclosures
Nucor Wire
Summary of results for test 50724121 (NCHRP 350 Tset 4-12)
Summary of results for test 50724121 (NCHRP 350 Tset 4-10) U.S. DEPARTMENT OF TRANSPORTATION

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