U.S. Department 

Of Transportation 

Federal Highway 

Administration

400 Seventh St., S.W. 

Washington, D.C. 20590 

June 19, 1990 

Refer to: HNG-14/SS-18 

Mr. Albert M. Moreno, Jr. 

President 

Minute Man Breakaway, Inc. 

Number One Moreno Place 

East Flat Rock, North Carolina 28726 

Dear Mr. Moreno: 

Thank you for your April 4 letter to Mr. L. A. Staron requesting Federal Highway 

Administration (FHW) acceptance of your company’s MMB-1HD breakaway couplings 

when used in dual post installations. Our December 29, 1989, letter accepted the MMB1HD for use with single posts or where posts were placed further than 7 feet apart. Your 

latest letter transmitted a copy of the Southwest Research Institute (SwRI) report (Project 

No. 6-3116-502) dated April 1990, containing the results of a pendulum test on these 

couplings in a dual 3 pound-per-foot signpost installation in strong soil. The test was 

conducted to assess the compliance of the couplings with FHWA breakaway 

requirements, which cite Section 7 of the 1985 American Association of State Highway 

and Transportation Officials’ (AASHTO) Standard Specifications for Structural Supports 

for Highway Signs, Luminaires and Traffic Signals.

The test used an instrumented 1,800 pound pendulum fitted with a 10 stage crushable 

nose, which simulates a 1979 Volkswagen Rabbit. The test article had two 3-foot 6-inch 

long high carbon steel flanged channel base posts weighting 3 pound-per-foot each, 

driven 3 feet 3 inches into the National Cooperative Highway Research Program 

(NCHRP) Report 230 S-1 (strong) soil. The MMB-1HD breakaway couplings were 

mounted on these base posts. Attached to the couplings were two 9-foot 3-inch mild steel 

sign posts (also 3 pound-per-foot flanged channel “U” posts) supporting an aluminum 

traffic sign. The posts were spaced 18 inches on center. The impact speed was 29.3 feetper-second (20 mph) and the change in velocity was 13.4 feet-per-second. One of the 

base posts translated and pulled up slightly, but the 3.5-inch stub height was still below 

the 4-inch maximum permitted. Calculations your provided show that the change in 

velocity for a 60 mph impact would be approximately 5.8 feet-per-second. 

These results show that the actual test and the calculated change in velocity of the tested 

couplings meet the change in velocity and stub-height requirements adopted by the 
FHWA. Thus a dual 3 pound-per-foot flanged channel sign support installed in a soil 

comparable t the NCHRP Report 230 strong soil, using MMB-1HD couplings is 

acceptable for use on Federal-aid highway projects, if proposed by a State. This 

acceptance is limited to breakaway characteristics of the couplings and does not cover the 

structural features of the support. Presumably, you will supply potential users with 

sufficient information on structural design and installation requirements to ensure proper 

performance. 

It is noted that the tested dual support installation was mounted in the NCHRP Report 

230 “strong” soil. To date, the FHWA has accepted, for restricted use, breakaway 

supports that have only been qualified through testing in one of the NCHRP soils. We 

are now administering a study, “Small and Large Sign Supports”, in which supports will 

be tested in both “strong” and “weak” soils. This pooled-fund study, with 27 

participating States, is likely to reveal performance problems with different soils. In this 

study, testing will be discontinued on any support system that fails in one of the soils and 

the system will be judged unacceptable until it is modified and found acceptable in both 

soils. Furthermore, this office will, from now on, only evaluate the breakaway 

acceptability of sign support system where there is assurance that they will meet our 

breakaway requirements in both “strong” and “weak” soils. Thus, it seems likely that 

near the end of the pooled-fund study (last testing scheduled for late 1992), the FHWA 

will begin to require that all new breakaway systems installed on Federal-aid highway 

projects be qualified as breakaway in both soils. Therefore, we suggest that you qualify 

your dual support system in “weak” soil in order to ensure its acceptability in the future. 

We anticipate that the States will require certification from Minuteman Breakaway, Inc., 

that the couplings and shear pins furnished have essentially the same chemistry, 

mechanical properties, and geometry as those used in the test, and that they will meet the 

FHWA change in velocity requirements. 

Since your company’s breakaway couplings are proprietary items, to be used in a 

Federal-aid highway project they: (a) must be supplied through competitive bidding with 

equally suitable unpatented items; (b) the State highway agency must certify that they are 

essential for synchronization with existing highway facilities or that no equally suitable 

alternate exists; or (c) they must be used for research or for a distinctive type of 

construction on relatively short sections of road for experimental purposes. Our 

regulations concerning proprietary products are contained in Title 23, Code of Federal 

Regulations, Section 635.411, a copy of which is enclosed. 

 Sincerely yours, 

 L.A. Staron, Chief 

 Federal-Aid and Design Division 

Geometric and Roadside Design Acceptance Letter Number SS-18