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


April 22, 2005

Refer to: HSA-10/WZ-206

Mr. Jan Miller
TrafFix Devices
220 Calle Pintoresco
San Clemente, California 92672

Dear Mr. Miller:

Thank you for your letter of March 22, 2005, requesting the Federal Highway Administration (FHWA) acceptance of your company's Little Buster mid-sized spring stand with "Safe Sleeve-350" supporting a plywood sign 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 Karco Engineering and video of the test. You requested that we find this stand acceptable for use on the NHS under the provisions of the 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:

The Little Buster sign stand with "Safe Sleeve-350" is an X-footprint portable sign stand having a steel upright 1.20 inches square, out of which telescopes a 1 inch square upper mast. The lower 18" portion of the outer mast is reinforced by the addition of a 18" length of 1.5" x 1.5" square x 0.100" thick overlapping black powder coated steel tubing with a fixed lower rigid sign bracket. This proprietary feature is known as the Safe Sleeve-350.

The total height of the extended mast is 92 inches, which can support a 48" x 48" diamond sign of 5/8-inch thick plywood at a height of 15 inches above the pavement. The mast is supported on dual springs mounted on 1-inch square folding legs, which measure 79 inches each when extended. Signs are held in place with a set of TrafFix Devices rigid sign brackets. The steel legs and mast tubes have a wall thickness of 0.070 inches, while the Safe Sleeve-350 is 0.100 inches. The stand weighs 72 pounds when supporting the plywood sign.


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 test is summarized in the table below.


NCHRP Report 350 Test 3-71

Stand Orientation

Head on

90 degrees

Sign Stand Tested

Little Buster with 48” x 48” x 5/8” plywood sign

Weight of Tested Stand

72 pounds

Mounting heights

15 inches

15 inches

Flags? Lights?



Mass of Test Vehicle

840 kg

Impact Speed

98.7 km/hr/(61.3 mph)

Velocity Change

2.77 km/hr, or 0.77 m/sec (max of 5 m/sec allowed)

Occupant Comp. Def.


Extent of contact

Hit windshield

Rotated over vehicle

Windshield Damage

Moderate cracking

No contact

Other notes

Maximum deformation of roof was 2 inches

Damage to the upper portion of the windshield was moderate to heavy, but there was no penetration of the glass, and the driver's view was not obscured. The damage resulted from the head-on impact. In the 90 degree impact the front of the car contacted the lower leading edge of the sign causing it to rotate. The leading corner of the sign contacted the hood, which propelled the sign up in the air and over the vehicle


Request 1: Acceptance of the TDI Little Buster sign stand with Safe Sleeve-350 for use with the tested 48" x 48" x 5/8" plywood signs, including signs of smaller size and thinner/lighter plywood materials.

Request 2: Acceptance of the TDI Little Buster sign stand with Safe Sleeve-350 for use with 48" x 48" x 0.100 inch and 0.125 inch solid aluminum and 3 mm aluminum laminate signs and smaller signs of same substrates. The weight of the tested plywood sign was 33 pounds. The weight of 0.080, 0.100, and 0.125 solid aluminum signs is 17.9 pounds, 22.4 pounds, and 28 pounds, respectively. As these panels each weigh less than the tested plywood panel, they should perform in a similar manner.

Request 3: Acceptance of the TDI Little Buster sign stands with Safe Sleeve-350 for use with additional sign shapes and sizes at the tested 15" mounting height. The following sizes (and smaller) and substrates are requested:

* Previously accepted substrates


The results of the testing met the FHWA requirements and, therefore, the devices described in Request 1 are acceptable.

We concur in Request 2 as the stand had been previously tested with 0.080 solid aluminum - the requested 0.100 and 0.125 aluminum are heavier but still weigh approximately 15% less than the tested 5/8-inch thick plywood substrate. The 3 mm aluminum laminate is heavier than the previously tested 2 mm aluminum laminate but much lighter and more flexible than either the plywood or solid aluminum substrates.

We concur in Request 3 as the proposed shaped signs would also engage the vehicle front end early in the crash event and are likely to perform in a similar manner to the tested signs.

The 48" x 60" and 48" x 72" vertical signs are larger in area and mass than the tested sign and may be used under the FHWA's extrapolation policy that avoids testing of all sign shapes and sizes. These tall vertical signs are in common use today, and are likely to impact the roofline under head-on impact conditions. Their use in 90 degree orientations ought to be discouraged, however.

In summary, the Little Buster stand, shown in the enclosed drawings for reference, supporting signs of the sizes and materials detailed above 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/
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety


Safety Home | FHWA Home | Feedback