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U.S. Department of Transportation

Federal Highway Administration

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


March 22, 2005

Refer to: HSA-10/WZ-201
(REVISED: October 19, 2005)

Mr. Tim Bedinger
Field Sales Manager
Allied Tube and Conduit
16100 South Lathrop Avenue
Harvey, Illinois 60426

Dear Mr. Bedinger:

Thank you for your letter of December 20, 2004, requesting the Federal Highway Administration (FHWA) acceptance of your company's Perforated Square Steel Tube framed dual support 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 the Texas Transportation Institute (TTI) 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."


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:

A 48-inch long vertical sleeve fabricated from 2-inch square, 14-gage perforated square steel tubing meeting ASTM A1011, Grade 50, was welded to the center of a 5-foot long skid fabricated from 2-inch square, 12-gage steel of the same grade using two lines of weld parallel to the length of the skid along the inside and outside edges of the sleeve. The sleeves were not welded to the skids along their front or back edges. A 3/8-inch diameter bolt was inserted through prefabricated holes in the sleeve approximately 1-inch off the top surface of the skid and welded in place. A 1 ¾-inch square by 11 feet long 12-gage perforated steel upright was inserted into the sleeve until it rested on the 3/8-inch diameter offset bolt. A 1 ¾-inch square by 38-inch long 14-gage cross brace was bolted to the sleeves and uprights at a height of 18-inches above ground using two 3/8-inch diameter by 4 ¼-inch long through bolts. The two vertical supports were place 36-inches apart center to center.

A 48 x 48-inch Choroplast corrugated plastic sign panel was attached to the vertical supports in a diamond configuration using six 5/16-inch diameter hex head bolts - three through each support. A 1 ½-inch diameter plastic washer was used between the head of the bolts and the sign substrate. The bottom edge of the sign was mounted 7 feet above ground. A 40-pound sandbag was placed on the front and back of each skid for a total of 4 sandbags. The unballasted weight of the sign supports system was 88.5 pounds. The Choroplast sign panel weighed 8 pounds.


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 six meters downstream turned at 90 degrees, as called for in our guidance memoranda.

The tests are summarized in the table below.

Test Number

4000001-ATC1, Report 350 Test No. 3-71

Sign Stand Orientation

Head on

90 degrees

Weight of Tested Stand

88.5 pounds

Mounting heights

7 feet

Flags? Lights?



Mass of Test Vehicle

1818 pounds

Impact Speed

61.7 mph (99.2 km/h)

54.9 mph (88.3 km/h)

Maximum O.I.V.

9.2 ft/s (2.8 m/s)

Velocity Change

3.0 m/s

2.7 m/s

Extent of contact

Sign struck roof

Sign struck roof

Windshield Damage

No contact

No contact

Other notes

Deformed roof 0.2 inch



Damage was limited to crushing of the bumper, grill, and hood, with a minor indentation in the roof. The roof contact was minimal, and there was no contact with the test vehicle's windshield.

The results of the testing met the FHWA requirements and, therefore, the devices described above and detailed in the enclosed drawings are acceptable for use on the NHS under the range of conditions tested, when proposed by a State.

You also requested acceptance of a single post version of this support. Accompanying this request was a letter from the TTI enumerating the key design elements of the tested sign stand as:

The TTI acknowledged that, as long as these same critical design elements were incorporated into it, the single-post version would be crashworthy based on the dual-post design being a "worst case." We concur in the TTI analysis, and conclude that the single post version is also acceptable for use.

Please note the following standard provisions that apply to the FHWA letters of acceptance:

Sincerely yours,

/original signed by George Ed Rice, Jr./

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

3 Enclosures

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