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                Safety Eligibility Letter WZ-121
  
  **Hardware Type:**
            Work Zone Devices
                          **Code:**
            WZ-121
                          **Date:**
            06/07/2002
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            Work Area Protection
                          **Device Description:**
            SCI48 Plastic Sign Blank
                          **View PDF:**
            wz121.pdf (106.28 KB)
    
    
Refer 
  to: HSA-10/WZ-121
Mr. Jeff Smith
  Work Area Protection Corporation
  P.O. Box 4087
  St. Charles, IL  60174-9081
Dear Mr. Smith:
Thank you for your letter of February 
  28, 2002, requesting Federal Highway Administration (FHWA) acceptance of your 
  company's SCI48 plastic sign blank as a 
  component of crashworthy traffic control devices for use in work 
  zones on the National Highway System (NHS).  Accompanying your letter was a 
  list of portable sign stands which have been successfully crash tested with 
  other sign substrates.  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."
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.
This 48 x 48 inch sign blank is blow molded of high-density polyethylene, with 
  tack offs on back to reduce straight line creasing.  Its thickness is 0.625 
  inches and it weighs approximately 11 pounds.  You requested that this sign 
  substrate be permitted as a substitute to a number of other substrates that 
  have been successfully crash tested on various manufacturers' sign stands.
Because this sign substrate has not yet been crash tested we cannot be sure 
  of its performance in every application.  Although there are certain substitutions 
  that are a reasonable extrapolation, others may only be applied on a case-by-case 
  basis.  Recent discussions with crash test experts have indicated that rounded 
  corners of signs are not always a feature that will improve the performance 
  during a crash.  In some cases the square cut corner will crush, absorbing some 
  of the energy of the impact.  Of course, in other cases the hard square corner 
  will penetrate the glass much more readily.  Therefore, we will review those 
  various applications here to assess the potential of your company's sign panel 
  to perform at least as well as the tested substrate.
Rigid Substrates:
Aluminum, Solid. 0.080, 0.100, 0.125 
  inches thick.  These substrates are usually made with rounded corners.  Because 
  they are much thinner, and also are usually heavier than the SCI48 blank, aluminum 
  signs are a "worst case" crash test scenario.  Therefore, any sign support, 
  permanent or temporary, that has been successfully crash tested with a solid 
  aluminum sign may also be used with the SCI48 sign.
Plywood. Plywood is sometimes rounded, 
  but usually cut square.  In the few tests run using square cut corners the windshield 
  was penetrated readily.  Plywood corners do not crush. Because the SCI48 is 
  significantly lighter than typical plywood substrates, it will be allowed as 
  a substitute on sign supports that have been successfully tested with plywood 
  signs.
Semi-Rigid Substrates:
Alpolic/Dibond/Renalite.  This two millimeter 
  thick aluminum laminate material appears to be very flexible when impacting 
  windshield glass.  Although the aluminum laminate sign blanks that have been 
  tested also have rounded corners, we cannot be certain that the SCI48 sign blanks 
  will flex in a similar manner when mounted on low to medium height stands.  
  We recommend that the SCI48 be crash tested on stands where aluminum laminate 
  signs were mounted at heights of 12 to 18 inches.  We do believe, however, that 
  the SCI48 will perform in an acceptable manner when mounted on portable sign 
  stands at a height at or above 5 feet as windshield contact is unlikely.
Reflexite Endurance.  This 5/8 inch thick 
  fluted Lexan sign panel is similar in thickness and weight to the SCI48 substrate.  
  As with the aluminum laminate signs we can expect the SCI48 to perform in a 
  similar manner when mounted on sign stands where Endurance was tested at heights 
  of 5 feet or above.  In tests where the Endurance sign was mounted low to the 
  ground (12" to 18" range) there was overall cracking of the test vehicle 
  windshields.  Because the structural differences that lead to success or failure 
  are not completely understood, we recommend that crash testing be conducted 
  at this height range.
Hinged ABS.  Here we concur that the 
  SCI48 is likely to be a less harmful sign substrate than the hinged ABS.  Therefore, 
  the SCI48 may be used on any sign stand that has been successfully crash tested 
  with the hinged ABS material at the same heights.
Corplast/coroplast/safetycor/safetyplast.  
  These lightweight corrugated plastic substrates are thinner than the SCI48 sign 
  blank.  Also, their resistance to flexing is dependent upon the orientation 
  of the fluting whereas the SCI48 is homogenous.  These significant differences
between the materials lead us to recommend 
  that the SCI48 be crash tested.  We do expect that the crash testing recommended 
  above will reveal a great deal about the performance of the SCI48 and may allow 
  us to then extrapolate our acceptance to sign stands tested with corrugated 
  plastic signs.
Use on Type III barricades.  The SCI48 
  may be used on any Type III barricade that has been successfully crash tested 
  with a 48 x 48 sign mounted above the top rail of the barricade.  This includes 
  those tested for the FHWA (WZ-40) and the Pennsylvania DOT (WZ-44).
In your request you included a table 
  of portable sign stands that you wished to use the SCI48 on. Here is a list 
  summarizing the stands we consider acceptable with the SCI48 without further 
  testing.
WZ #
      Manufacturer
      Model
      DescriptionWZ-44
      Pennsylvania DOT
      Type III Barricade
      Sign above top railWZ-46
      Traffix Devices
      Big Buster
      60 inch mounting ht.WZ-52
      Reflexite
      DF4700TX
      60 inch mounting ht.WZ-59
      Eastern Metal / USA Sign
      X-602
      60 inch mounting ht.WZ-69
      MDI
      4860K Breakaway
      60 inch mounting ht.WZ-73
      Traffix Devices
      Big Buster
      60 inch mounting ht.WZ-73
      Traffix Devices
      Big Buster, with light
      60 inch mounting ht.WZ-74
      United Rentals
      Hi-Pro 350
      84 inch mounting ht.WZ-78A
      Eastern Metal / USA Sign
      E-350 Econo Stand
      15 inch mounting htWZ-78A
      Eastern Metal / USA Sign
      X-842
      12 inch mounting ht.WZ-78A
      Eastern Metal / USA Sign
      X-602
      60 inch mounting ht.WZ-78B
      Eastern Metal / USA Sign
      X-602
      60 inch mounting ht.
Findings
The signs in the above table have been 
  shown to perform in an acceptable manner when tested with sign substrates more 
  rigorous than the SCI48.  We expect that they would also perform in an acceptable 
  manner when tested with the SCI48 plastic sign panel.  Therefore, the devices 
  described above and shown in their respective FHWA acceptance letters are acceptable 
  for use on the NHS under the range of conditions tested, when proposed by a 
  State.
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-121 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 signs and stands covered by this 
  letter 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

202-366-4000Subscribe to email updates
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