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                Safety Eligibility Letter WZ-115
  
  **Hardware Type:**
            Work Zone Devices
                          **Code:**
            WZ-115
                          **Date:**
            06/07/2002
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            United Rentals Highway Technologies
                          **Device Description:**
            Portable Sign Trailer
                          **View PDF:**
            wz115.pdf (391.85 KB)
    
    
Refer to: HSA-10/WZ-115
Mr. Henry Ross
  United Rentals Highway Technologies
  P.O. Box 7050
  Villla Park, Illinois  60181-7050
Dear Mr. Ross:
Thank you 
  for your letters of January 29 and March 15, 2002, requesting Federal Highway 
  Administration (FHWA) acceptance of your company's portable sign trailer as 
  a crashworthy traffic control device for use in work zones on the National Highway 
  System (NHS).  Accompanying 
  your letter was a letter report of crash testing conducted by E-Tech testing 
  services and a video of the tests.  You requested that we find these devices 
  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.”  On April 5, 2002, in response to our request, 
  you provided additional information via the Internet.
Introduction
The FHWA guidance on crash testing of 
  work zone traffic control devices is contained in two memoranda.  The first, 
  dated July 25, 1997, titled “INFORMATION: Identifying Acceptable Highway 
  Safety Features,” established four categories of work zone devices: Category 
  I devices were those lightweight devices which could be self-certified by the 
  vendor, Category II devices were other lightweight devices which needed individual 
  crash testing, Category III devices were barriers and other fixed or massive 
  devices also needing crash testing, and Category IV devices were trailer mounted 
  lighted signs, arrow panels, etc.  The second guidance memorandum was issued 
  on August 28, 1998, and is titled “INFORMATION: Crash Tested Work Zone 
  Traffic Control Devices.”  This later memorandum lists devices that are acceptable 
  under Categories I, II, and III.
The trailer consists of 2 x 2 inch square 
  steel (ASTM A-500, Grade B) tubing with a wall thickness of 1/8 inch.  Two 14 
  inch diameter wheels are affixed to the axle, which is 45 inches long.  The 
  tongue is 6 feet long. The 2 inch diameter steel pipe mast is six feet in length 
  and carries a framework that supports signs up to 51 inches wide.  The mast 
  is slides into a 2-1⁄2 inch diameter pipe, which is affixed to a hinged connection 
  that, along with the overall trailer design, is illustrated in the enclosed 
  drawings for reference.  The overall weight of the trailer and sign is 220 pounds 
  (99.8 kg).
Testing
Full-scale automobile testing was conducted 
  on your company's devices.  Two stand-alone  examples of the device were tested 
  in separate impacts.  One was struck head-on and the other was impacted at 90 
  degrees. The complete device as tested is shown in Enclosure 1.  The crash test 
  is summarized in the table below:
Test Number
    05-7210-016
    05-7210-017Test Article
    United Rental Portable Sign TrailerOrientation
    Head-on
    PerpendicularHeight to Bottom of Sign
    1276 mm (50 in)
    1276 
        mm  (50 in)Height to Top of Sign
    2800 mm (110 in)
    2800 mm (110 in)Flags or lights
    None
    NoneTest Article Mass (each)
    99.8 kg
    99.8 kgVehicle Inertial Mass
    819 kg
    816 kgImpact Speed
    101.8 km/hr
    99.7 km/hrVelocity Change
    3.9 m/s
    3.9 m/sOccupant Impact Speed
    3.9 m/s
    3.9 m/sVehicle crush
    None
    Roof crushOccupant Compart. Intrusion
    None
    Sign edge entered vehicleWindshield Damage
    No Contact
    PenetrationFindings
This trailer is somewhat similar to one crash-tested at the Federal Outdoor 
  Impact Laboratory for the State of Montana.  The Montana trailer was judged 
  acceptable for use in FHWA Acceptance Letter WZ-19 dated July 26, 1999.  The 
  Montana trailer was also tested via two impacts, at zero and 90 degrees respectively.  
  There was a significant difference in the testing procedure, however, in that 
  the sign panel was oriented perpendicular to the direction of vehicle travel 
  in both impacts of the Montana trailer, causing the face of the sign 
  to impact the vehicle in both tests.  In testing the UR trailer, the entire 
  rig, sign and all, was turned through an angle of 90 degrees.  This resulted 
  in the edge of the sign facing the test vehicle in the second test.
Apparently the testing of the Montana 
  trailer was conducted in this manner because it was known that the leading edge 
  of an end-on sign would be very likely to cause severe damage.
It was also recognized that these sign 
  trailers are removed at the end of the workday.  Therefore,  the situation where 
  the sign is turned 90 degrees in order to obscure the message from drivers does 
  not occur.
The URL trailers were tested with the 
  sign blank oriented perpendicular to the trailer tongue in both tests.  In the 
  second test the thin edge of the sign penetrated the windshield and caused extensive 
  roof damage.  If the second test had been run with the sign perpendicular to 
  the windshield it is expected that the results would be comparable to those 
  of the Montana trailer.
The results of the testing met the FHWA 
  requirements except as noted and, therefore, the devices described above and 
  shown in the enclosed drawings for reference are acceptable for use on the NHS 
  under the range of conditions tested, when proposed by a State.  The failing 
  results of the second test are an indication that the trailer should never be 
  left with the sign oriented parallel to traffic.  The design of the United Rentals 
  trailer incorporates a hinge base feature that makes it relatively easy to obscure 
  the message of the sign when it is no longer appropriate.
Please note the following standard provisions that apply to FHWA letters of 
  acceptance:
Our acceptance is limited to the crashworthiness characteristics of the 
    devices and does not cover their structural features, nor conformity with 
    the Manual on Uniform Traffic Control Devices.
  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 FHWA and NCHRP Report 350.
  To prevent misunderstanding by others, this letter of acceptance, designated 
    as number WZ-115 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 United Rentals trailer may include 
  patented components and if so are considered "proprietary."  The use 
  of proprietary work zone traffic control devices in Federal-aid projects is 
  generally of a temporary nature.  They are selected by the contractor for use 
  as needed and removed upon completion of the project.  Under such conditions 
  they can be presumed to meet requirement "a" given below for the use 
  of proprietary products on Federal-aid projects.  On the other hand, if proprietary 
  devices are specified 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 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, a copy of which is enclosed.
Sincerely yours,
Carol H. Jacoby, P.E.
Director, Office of Safety Design
Enclosure U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

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