November 26, 2002

Refer to: HSA-10/WZ-133

Mr. Ron Faller
Midwest Roadside Safety Facility
1901 “Y” Street, Bldg. C
P.O. Box 880601
Lincoln, Nebraska  68588-0601

Dear Dr. Faller:                                   

Thank you for your September 12, 2002, letter requesting Federal Highway Administration (FHWA) acceptance of the Minnesota Department of Transportation (DOT) temporary work zone sign stand as a crashworthy traffic control device for use in work zones on the National Highway System (NHS).  Accompanying your letter was a report of crash testing you conducted and a CD 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 were those lightweight devices which could be self-certified by the vendor, Category II devices were other lightweight devices which needed individual crash testing, Category III devices were barriers and other fixed or massive devices also needing crash testing, and Category IV devices were trailer mounted lighted signs, arrow panels, etc.  The second guidance memorandum was issued on August 28, 1998, and is titled AINFORMATION: Crash Tested Work Zone Traffic Control Devices.”  This later memorandum lists devices that are acceptable under Categories I, II, and III.

A description of the device follows:

The Minnesota DOT rigid panel portable sign support is a stiffened perforated square steel tube “H-Footprint” device:


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 MWRSF 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.

The two tests and their results summarized below were within these constraints.

Stand-alone examples of the devices were tested in separate tests, one head-on and one turned at 90 degrees, as called for in our guidance memoranda.  The complete device, as tested is shown in Enclosure 1.  The crash test is summarized in the table below:

Test Number



Test Article



Flags or lights

One lightweight warning light on each stand

Test Article Mass (each)

45.8 kg (91 pounds) plus ballast

Bogie Inertial Mass

974 kg (2148 pounds)

Impact Speed

97.5 km/hr (60.6 mph)

98.8 km/hr (61.4 mph)

Approx. Velocity Change

10 km/hr, 2.78 m/s

10 km/hr, 2.78 m/s


The rigid frame of these stands caused them to be pushed ahead of the bogie, or knocked to one side.  Neither showed any potential for approaching the windshield or causing any other passenger compartment intrusion.  The trajectory of the sign stands in these tests indicate that the bogie vehicle, even though it was not within the specification range of an NCHRP Report 350 820C test vehicle, was acceptable for establishing the crashworthiness of the stands.  The results of the testing met the FHWA requirements and, therefore, the devices described above and shown in the enclosed drawings for reference 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 FHWA letters of acceptance:

Sincerely yours,

Carol H. Jacoby, P.E.
Director, Office of Safety Design