Skip to contentSkip to contentUnited States Department of Transportation - Federal Highway Administration FHWA HomeFeedback

DOT logo
U.S. Department of Transportation

Federal Highway Administration

400 Seventh St., S.W.
Washington, D.C. 20590

January 13, 2006

Refer to: HSA-10/WZ-223

Mr. Ken Russell
3D Specialties
1110 25th Avenue North
Fargo, North Dakota 58102

Dear Mr. Russell :

Thank you for your letter of December 9, 2005, requesting the Federal Highway Administration (FHWA) acceptance of your company's modification to the Minnesota Portable Sign Support as a crashworthy traffic control device for use in work zones on the National Highway System (NHS). Accompanying your letter was a drawing of the support that was found acceptable in the FHWA letter WZ-133 dated November 26, 2002. You requested that we find a modification to this portable sign stand 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. The Minnesota Department of Transportation (Mn/DOT) rigid panel portable sign support is a stiffened perforated square steel tube "H-Footprint" device. You requested that a substitution for the 38.1 mm (1.5 inch) horizontal legs be allowed, using 50.8 mm (2.0 inch) perforated square steel tube in either 12 gage or 14 gage steel.

A description of the modified device follows:

Testing and Findings

The results of the Mn/DOT testing met the FHWA requirements and the FHWA acceptance letter WZ-133 was issued. We concur that your proposed modification increases the strength of the legs without significantly increasing the weight and would not adversely affect the performance of this sign stand. Therefore, the modified sign stand described above is 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 the FHWA letters of acceptance:

Sincerely yours,

/original signed by /

John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety


Safety Home | FHWA Home | Feedback