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                Safety Eligibility Letter B-168
  
  **Hardware Type:**
            Longitudinal Barriers and Bridge Rails
                          **Code:**
            B-168
                          **Date:**
            02/02/2008
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            Mac Ray MassHighways
                          **Device Description:**
            Annisquam River Bridge Rail
                          **View PDF:**
            b168.pdf (195.32 KB)
    
    HSSD/B-168


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-168

Malcolm H. Ray, P.E., Ph.D.
Department of Civil Engineering
Worcester Polytechnic Institute
100 Institute    Road
Worcester,   MA 01609
	
Dear Dr. Ray:
Thank you for your  letter of September 6, 2007, requesting the Federal Highway Administration’s  (FHWA) acceptance of a Massachusetts Highway Department (MHD) modification to  the Minnesota Type Three Combination Bridge Rail. You requested that we find this barrier  acceptable for use on the National Highway System (NHS) under the provisions of  the National Cooperative Highway Research Program (NCHRP) Report 350  "Recommended Procedures for the Safety Performance Evaluation of Highway  Features.” Crashworthiness of the Test Level  3 (TL-3) barrier, intended for use on the Annisquam River   Bridge, was evaluated  using finite element modeling.**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.”
**Description**
  The 35-inch tall Minnesota railing was  tested to NCHRP Report 350 TL-4 and accepted by the FHWA in our memorandum “Crash  Testing of Bridge Railings” dated May 30, 1997. The 
  32-inch tall  Annisquam/MHD version (shown in the enclosed drawings) varies from the tested  railing in a number of dimensions including overall height, height of concrete  parapet, and details of the post and rail. The dimensions and test results of the  Minnesota TL-4 rail, and the six different Annisquam Bridge  railing proposals that were evaluated with finite element analysis (FEA) for  TL-3, are detailed in “Table 17”, enclosed for reference.
Current FHWA policy  does not allow the substitution of computer modeling for the NCHRP Report 350 crash  test evaluation of new devices. However,  we have considered the results of FEA when evaluating modified devices that had  already been evaluated and accepted using full 
  scale crash testing. Because the requested modifications retain  the significant structural details of the Minnesota design, and the requested railing  is comparable to other crash tested concrete-parapet-and-steel-rail designs, we  concur in your assessment.
**Findings**
The bridge rail system described above and detailed in the  enclosed drawings is acceptable for use on the NHS under the NCHRP Report 350  Test Level 3 conditions tested, when proposed by a highway agency.
Please note the following standard provisions that apply to  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-168, 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.
  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
Annisquam River Bridge (Sheet No. 1 of 4)
Annisquam River Bridge (Sheet No. 3 of 4)
Table 17 - Design features and NCHRP Report 350 evaluation criteria for the six design alternatives. U.S. DEPARTMENT OF TRANSPORTATION

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