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

December 15, 2005

Refer to: HSA-10/WZ-219

Dr. Ron Faller
Midwest Roadside Safety Facility
527 Nebraska Hall
P.O. Box 880529
Lincoln, Nebraska 68588-0529

Dear Mr. Faller:

Thank you for your letter of July 22, 2005, requesting the Federal Highway Administration (FHWA) acceptance of Missouri's Ground Mounted Temporary 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 you conducted 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:

The Missouri ground mounted portable sign support is a single tube of 1.25 in square galvanized Telespar steel tubing with 0.125 in wall thickness and a length of 30 in. The tube is mounted to an anchor that consists of a 0.75 in diameter by 12 in long steel rod with a 6 in wide x 5.25 in high x 0.125 in thick triangle soil plate. A 3 in diameter washer with a
0.156-inch thickness was welded to the steel rod at the top of the attached soil plate. The anchor is ASTM Grade A-513 steel. The vertical tube is welded to the top of the anchor's washer.

The vertical fiberglass rib of the roll-up sign is secured to the support using a panel-to-post clamp. The clamp is 1.625 in wide x 5 in long U-shaped with 1 in long legs and a thickness of 0.125 in. It is fabricated from ASTM A-36 steel. A 0.25 in diameter by 2.25 in long ASTM A-307 Grade 2 bolt with nut is inserted through a hole in the center of the U-shaped clamp and tack welded around the bolt head.

The sign panel is 48 x 48 reflective vinyl on a crossbrace. The vertical member is 0.25 in thick x 1.25 in wide by 66 in long with a 0.3125 in diameter hole drilled 8.25 in from the bottom. The horizontal brace is 0.1875 thick x 1.25 in wide by 66 in long.

Height to bottom of sign: 18 inches
Height to top of sign: 86 inches
Weight of sign post: 6.0 pounds
Weight of clamp and bolt: 0.5 pounds
Weight of panel and crossbraces: 6.3 pounds
Total weight of system: 12.8 pounds.

Full-scale automobile testing of an earlier design resulted in an unacceptable amount of windshield damage on the test vehicle. It was determined that early release of the sign from the support tube contributed to the damage. The bolt used to apply pressure on the base of the vertical crossbrace was replaced with a through bolt. This improved the performance to the point where no significant components of the stand came near the bogie's simulated windshield.

Bogie vehicle testing was conducted on the Missouri ground mounted sign supports. Stand-alone examples of the device were tested in separate runs, one head-on and one turned at
90 degrees.

The tests are summarized in the table below.

NCHRP Report 350 Test 3-71

Test Number




Sign Stand Tested


90 degrees


Mass of Test Vehicle

2,467 pounds

Impact Speed, km/hr (mph)

99.3 (61.7)

104.4 (64.9)

100.7 (62.6)

Velocity Change m/sec (fps)

0.97 (3.22 fps)

1.5 (4.99)

1.17 (3.81)

Extent of contact

Only vinyl*

Only vinyl*

No contact

Windshield Damage




Other notes

* Only the retroreflective vinyl sign contacted the "windshield" vicinity of the bogie.

This crash-testing program used a hard-nosed bogie vehicle of a mass larger than the standard 820C test vehicle. There are significant constraints involved in using such a non-standard testing device, some of which are:

  1. The potential vehicle velocity change must be considered insignificant.
  2. The crush characteristics of an automobile bumper must not be expected to have a significant affect on the trajectory of the test article.
  3. The profile of the bogie vehicle must be configured to replicate the outline of a production vehicle. The Midwest Roadside Safety Facility bogie was configured to replicate the outline of a Geo Metro, a vehicle commonly used in testing of work zone devices.
  4. No part of the test article may intrude into the windshield area of the vehicle after impact.

Contact between the test article and the vehicle was limited to the bumper and hood areas of the bogie. In some cases the vinyl sign separated from the crossbraces and slid up and across the windshield but would not have caused any damage at all.

The results of the testing met the FHWA requirements and, therefore, the Missouri Ground Mounted Temporary Sign Stand 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 /

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


Safety Home | FHWA Home | Feedback