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U.S. Department of Transportation

Federal Highway Administration

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

December 19, 2005

Refer to: HSA-10/WZ-221

Mr. Mark G. Carrk, Sr.
VP - Risk Management
Mathy Construction Co.
920 10th Avenue North
P.O. Box 189
Onalaska, Wisconsin 54650

DearMr. Carrk, Sr.:

Thank you for your letter of June 9, 2005, requesting the Federal Highway Administration's (FHWA) acceptance of your company's A-Frame portable sign stand as a crashworthy traffic control device for use in work zones on the National Highway System (NHS). Accompanying your letter were reports of crash testing conducted by E-TECH Testing Services and 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." Additional information on the windshield deformation was supplied by E-TECH on
December 6, 2005, in response to our request.

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 Mathy Construction Sign Stand consists of a sign support formed from a pair of 16mm hot rolled steel round bar legs. The legs are hinged together at the top with a pair of 19 mm

Schedule 40 pipe joints that are welded to one of the legs and disposed about the other. Metal flat washer "stops" are welded to adjacent legs to limit the spread angle between the legs to approximately 60 degrees. The frame unfolds into an A-frame like support for a 1219 x 1219 mm by 2.03 mm thick aluminum sign panel. The base of the panel rests in a 25 x 25 mm by 3mm angle iron "pocket" welded to one of the legs. When deployed the base of the sign is at a nominal 305 mm above the ground. The top of the sign is secured to the frame at the top with a pair of rubber "bungee" cords crossed over one another. The total test article mass was 16.3 kg and the sign mass was 8.2 kg. A drawing of the Mathy Construction Sign Stand is enclosed for reference.

Full-scale automobile testing was conducted on your company's devices. Two stand-alone examples of the device were tested in tandem, one head-on and the next placed 6 meters downstream turned at 90 degrees, as called for in our guidance memoranda.

The tests are summarized in the table below.

NCHRP Report 350 Test 3-71

Test Number

Sign Stand Tested



Weight of Tested Stand

16.3 kg

Mounting heights

305 mm

Flags? Lights?



Mass of Test Vehicle

818 kg

Impact Speed

101.1 km/hr

99.7 km/hr

Velocity Change

0.4 m/s

0.4 m/s

Extent of contact

Both signs hit windshield

Windshield Damage

Extensive damage across entire windshield

Other notes

Maximum windshield deformation 2.625 inches


Damage to the windshield was extensive due to the impact of the solid aluminum sign panels. There was general overall cracking and flexing of the glass, but there were no holes through the plastic laminate layer because the flat face of the sign impacted the windshield during the head-on test. Our guidance has a "preferred" limit of 2 inches of deflection, with a maximum allowable deflection of 3 inches. Devices that cause the windshield to deflect between 2 and 3 inches can be found "acceptable, but marginal.

The results of the testing met the FHWA requirements and, therefore, the device described in request above and detailed in the enclosed drawings is marginally acceptable as a test-level 3 device 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


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