U.S. Department 

Of Transportation 

Federal Highway 

Administration

400 Seventh St., S.W. 

Washington, D.C. 20590 

December 29, 1989 

Refer to: HNG-14/SS-16 

Mr. Albert M. Moreno, Jr. 

President 

Minute Man Breakaway, Inc. 

Number One Moreno Place 

East Flat Rock, North Carolina 28726 

Dear Mr. Moreno: 

This is in response to your September 22 and December 12 letters requesting Federal 

Highway Administration (FHWA) acceptance of your company’s revised MMBbreakaway device. The FHWA originally accepted the MMB-1 on March 10, 1988. 

Your September 22 letter detailed changes you made to the design of the casting which 

were intended to increase the structural capacity of a support for winds against the back 

of the sign. Your December letter responded to our concerns that the breakaway 

performance of the revised “MMB-1HD” was uncertain, and that dynamic and static 

testing should be performed. Your December letter also transmitted copies of the 

Southwest Research Institute (SwRI) “Pendulum Test Report of a Model MMB-1HD 

Breakaway Sign Support”, results of the static testing that indicated the stronger direction 

of the support, and shop drawings illustrating the device. The major changes in the 

design of the MMB-1 are the increase in the size of the casting and elimination of the 

steel tether cable. We consider elimination of the tether significant the high-speed 

performance of your break away unit. Users of the unit should be cautioned against 

installing tethers. 

The SwRI dynamic test was conducted using a 1,800-pound instrumented pendulum with 

a 10-stage crushable nose impacting at 18 inches above the ground. The test article 

consisted of a 3-foot 6-inc long high carbon steel flanged channel base post weighing 

three pounds-per-foot, driven 3 feet 3 inches into the National Cooperative Highway 

Research Program Report 230 S-2 (weak)soil, the MMB-1HD breakaway unit, and a 9-

foot 3-inch mild steel sign post (also a three pound-per-foot flanged channel :U: post) 

supporting a 2.5 x 2.5-foot aluminum stop sign. The impact speed was 29.3 feet-persecond (20 m.p.h.) and the change in velocity was 7.3 feet-per-second. The base post 

translated and pulled up slightly in the “weak” soil, but the 3.5-inch stub height was still 

below the 4 inch maximum permitted by the American Association of Highway 

Transportation Official (AASHTO) and FHWA requirements. Calculations you provided 
show that the change in velocity for a 60 m.p.h impact would be approximately 3.1 feetper-second. 

Therefore, the revised Minute Man Breakaway device, known as MMB-1HD, will be 

acceptable for use on Federal-aid highway projects in both strong and weak soil 

conditions, if requested by a State, in single three pound-per-foot installations of flangedchannel posts. This acceptance is limited to the features. Presumably you will supply 

potential users with sufficient information on structural design and installation 

requirements to ensure proper support performance. 

We anticipate that the States will require certification from Minute Man Breakaway, 

Incorporated, that the devices furnished have essentially the same composition, 

mechanical properties, and geometry as the tested device and that they will meet the 

FHWA and AASHTO change in velocity requirements. 

 Sincerely yours, 

 L. A. Staron, Chief 

 Federal-Aid and Design Division