August 11, 2004
Refer to: HSA-10/WZ-190
Mr. Chuck Mettler
Plastic Safety Systems
2444 Baldwin Road
Cleveland, Ohio 44104
Dear Mr. Mettler:
Thank you for your letter of May 29, 2004, requesting Federal Highway Administration (FHWA) acceptance of your company's Anchor Sign Stand as a crashworthy traffic control device for use in work zones on National Highway System (NHS). Accompanying your letter were photographs and engineering drawings of the stand. 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" based on comparison to your Type III barricade which was successfully crash tested using similar components.
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 are those lightweight devices which are to be self-certified by the vendor, Category II devices are other lightweight devices which need individual crash testing but with reduced instrumentation, Category III devices are barriers and other fixed or heavy devices also needing crash testing with normal instrumentation, and Category IV devices are trailer mounted lighted signs, arrow panels, etc., for which crash testing requirements have not yet been established. 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.
A brief description of the devices follows:
The Anchor Sign Stand consists of components which have been found acceptable in the PSS Type III barricade systems. The Anchor feet were accepted in the FHWA acceptance letters WZ-152 and WZ-166. The HDPE uprights are the same as those accepted in WZ-61, WZ-152, and WZ-166. The stand will support a 48x48 inch diamond roll-up sign at a mounting height of approximately 13 inches and a top height of approximately 80 inches. The pultruded fiberglass spreaders supporting the roll up sign are 1 1/4 inch wide. The maximum thickness of the vertical spreader is 1/4 inch, and the maximum thickness of the horizontal spreader should be 3/16 inch. And additional 34-inch long fiberglass rib is attached to the uprights and the sign's vertical spreader at a height of 25 inches above the ground to provide additional stability.
Full-scale automobile testing was conducted on your company's Type III barricades using similar framing materials. There was only slight to moderate cracking of the windshield from the impacts of the barricade rails and uprights which extended to a height of 64 inches.
The components of this stand conform to those used in your crash tested and accepted Type III barricade. Also the proposed sign stand can be considered a "compact" portable sign stand that has no substantial components that are likely to come in contact with the windshield. The typical "compact" stand is an "X-footprint" design with a steel or aluminum mast no taller than approximately 12 to 18 inches tall that supports the vertical fiberglass spreader of a roll up sign.
We concur in your assessment that the Anchor Sign Stand would meet the crashworthiness requirements of the FHWA and, therefore, the devices described above and detailed in the enclosed drawings are acceptable for use on the NHS under the range of conditions the "parent" type III barricade was tested, when proposed by a State.
Please note the following standard provisions that apply to FHWA letters of acceptance:
/Original Signed by/
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety