Federal Highway Administration
400 Seventh St., S.W.
Washington, D.C. 20590
May 3, 2006
Refer to: HSA-10/WZ-235
Mr. Randy Held
5004 Steelhead Street
Juneau, Alaska 99801
Dear Mr. Held :
Thank you for your email correspondence of November 28, 2005, requesting Federal Highway Administration (FHWA) acceptance of your company's RubberSteeltm method for overlaying sign panels as crashworthy, for use in work zones on the National Highway System (NHS). You provided a sample, and requested that we find this system 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."
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. Our new acceptance process was outlined in our memorandum "FHWA Hardware Acceptance Procedures – Category 2 Work Zone Devices" dated November 11, 2005.
A brief description of the devices follows:
The "RubberSteeltm" material is a flexible, magnetic attractive panel that can be applied to sign substrates. Magnetic sheeting panels that carry alternate legends or symbols may then be placed on the sign as the traffic situation warrants. The system can also be use to obscure the entire sign when not needed.
Your request was to permit the use of signs consisting of RubberSteeltm affixed to corrugated plastic substrates. As no crash tests have been conducted on this product, you asked that the FHWA accept the use of the RubberSteeltm modified signs on sign stands that have been successfully crash tested with conventional rigid substrates such as wood and solid aluminum.
The RubberSteeltm material weights approximately 6.85 ounces per square foot. For a sign measuring 36 x 36 inches, the weight of a solid aluminum substrate (0.080 inches thick) is approximately 8.7 pounds. A similar sized sign of corrugated plastic with RubberSteeltm weighs approximately 7.0 pounds. As most plywood sign substrates are heavier than solid aluminum, they too would be substantially heavier than a corrugated plastic substrate with RubberSteeltm applied.
Because the modified signs would weigh no more than the conventional solid sign substrates they would replace, they can be expected to perform at least as well when impacted when mounted on the following categories of sign supports:
The results of the testing of the original sign stands and supports met the FHWA requirements and, therefore, the portable stands and permanent sign supports described above, modified with RubberSteeltm material, are acceptable for use under the range of conditions the original sign stands were tested, when proposed by a State.
Please note the following standard provisions that apply to the FHWA letters of acceptance:
/original signed by George Ed Rice, Jr/
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety
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