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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-183

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 Stand for rigid 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 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 12.7 mm thick, 1219 mm diamond shaped plywood 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 29.9 kg. One 16 kg sand bag was placed at the end of each 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 plywood sign

Test Number

05-3483-008

05-3843-009

Sign Stand Tested

Perpendicular Featherweight

Head-On Featherweight

Weight of Tested Stand

29.9 kg (66 pounds)

Mounting heights

1524 mm (60 inches)

Flags? Lights?

None

Mass of Test Vehicle

825 kg

Impact Speed

101 km/hr (62.8 mph)

101.8 km/hr (63.3 mph)

Velocity Change

0.5 m/s

1.61 m/s

Extent of contact

Bumper, Grille, Hood

Grille, Hood, Roof

Windshield Damage

No contact

No contact

Findings

Damage was limited to scrapes and dents to the bumper, grille, hood, and roof. There was no contact between the signs and the windshield. The velocity changes are well below the 5 m/s permitted by the NCHRP Report 350. The results of the testing met the FHWA requirements and, therefore, the devices described in the various requests 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.

Mr. Ross also requested that this acceptance extend to solid aluminum signs as well as the tested plywood, and for other sign shapes and sizes as long as the overall area does not exceed that of the tested signs. The tested 48 x 48 x 1/2 plywood sign weighed 24.4 pounds while 48 x 48 x 0.080 aluminum signs weigh 19 pounds. Because the tested signs detached from the uprights almost immediately after impact, and passed over the vehicle without contacting the windshield or roof, we concur that solid aluminum signs may also be used on this stand, under the range of conditions tested. Your request for additional sign shapes and smaller sizes is also acceptable as it is in line with our stated policy. However, the bottom of the signs should be no lower than the bottom of the tested sign (5 feet.)

The results of the testing met the FHWA requirements and, therefore, the devices described in the various requests 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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