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U.S. Department of Transportation

Federal Highway Administration

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

 

March 11, 2005

Refer to: HSA-10/WZ-184

Mr. LeRoy Goff
United Rentals Highway Technologies
880 North Addison Road
P.O. Box 7050
Villa Park, Illinois 60181-7050

Dear Mr. Goff:

This is in response to Mr. Henry Ross's letter of March 19, 2004, requesting Federal Highway Administration (FHWA) acceptance of your company's Featherweight II Stand for rollup signs as a crashworthy traffic control devices 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." Please accept our apologies for not promptly following up on this action after Mr. Ross's departure from your company last year.

Introduction

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 Featherweight II Sign Stand is a compact telescoping type portable sign system with a rigid upright support. It has four telescoping square tube support legs with spring-loaded detents that form a nominal 1778 x 1143 mm X-shaped pattern when extended. The outer support leg is made of 31.8 mm square 14ga ASTM A500GD B welded steel tubing. The inner support leg is made of 25.4 mm square 2.2 mm wall aluminum tubing. The tips of the inner support legs are rubber capped. The support legs pivot on a central two-piece steel "leg support" bracket which is equipped with a spring loaded detent mechanism that allows the legs to be unlocked and folded up compactly. The bracket holds the upright support with spring-loaded detents. The upright consists of three telescoping sections of 2.4 mm wall aluminum tubing: 38.1 mm, 31.8 mm, and 25.4 mm square.

The stand supports a 1219 mm diamond shaped rollup vinyl sign at a nominal 1524 mm height as measured from the bottom edge of the sign to the ground level. The stand with sign weights 18 kg. One 16 kg sand bag was placed at the end of two of the four legs.

Testing

Full-scale automobile testing was conducted on your company' devices. Two stand-alone examples of the device were tested in separate test runs, one perpendicular and the second head-on. Both devices were placed on flat, clean dry asphalt surfaces. The tests are summarized in the table below.

 

Featherweight stand with rollup sign

Test Number

05-3483-007

Sign Stand Tested

Head-on

Perpendicular

Weight of Tested Stand

18 kg (40 pounds)

Mounting heights

1524 mm (60 inches)

Flags? Lights?

None

Mass of Test Vehicle

845 kg

Impact Speed

105.4 km/hr

100.0 km/hr

Velocity Change

1.5 m/s

1.4 m/s

Extent of contact

Sign hit windshield

Sign hit roof

Windshield Damage

Extensive cracking

Other notes

No holes through the windshield

Findings

In addition to striking the bumper, grille, and hood, there was extensive contact between the signs and the mast with the windshield resulting in overall cracking. No one location resulted in cracking so dense as to impair the ability of a driver to view the road ahead, nor were there any holes in the windshield. The velocity changes are well below the 5 m/s permitted by NCHRP Report 350. Because of the contact with the windshield, the fiberglass ribs of the roll up signs in use should no thicker or wider than those tested.

You also asked for acceptance of this stand using different sizes and shapes of roll up signs. We concur in this request provided the mounting height of the sign is no lower than the tested sign.

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

Sincerely yours,

/Original Signed by/
~for~

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

Enclosure


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