U.S. Department 

Of Transportation 

Federal Highway 

Administration

400 Seventh St., S.W. 

Washington, D.C. 20590 

August 19, 1986 

Refer to: HNG-21/SS-02 

Christopher Meyer P.E. 

Product Applications Engineer 

Trus Joist Corporation 

P.O. Box 7984 

3210 E. Amity Road 

Boise, Idaho 83707 

Dear Mr. Meyer: 

This is in response to your August 1 letter requesting Federal Highway Administration 

(FHWA) acceptance of your MICRO=LAM laminated veneer lumber breakaway 

signposts for use on Federal-aid highway projects. You enclosed a copy of an 

Engineered Wood brochure, a videotape and a Southwest Research Institute Report No. 

06-1102-001 Dated July, 1986 containing full-scale crash test information. 

Your 14 7/8-inch by 7 7/8-inch laminated veneer lumber post having a wall thickness of 

1 1⁄4-inches and having 45-degree mitered corners was tested. The post was placed in predrilled holes and backfilled. Four 1-inch diameter holes were then drilled on the two 

sides of the post parallel to the direction of travel. Two of the holes were at the 3-inch 

above ground heights and the other two holes were at the 18-inch height. A saw cut 

parallel to the ground was then made that connects each set of holes. Enclosed is a copy 

of the tested design for your ready reference. 

One test was conducted with an 1,840-pound vehicle impacting the sign post at 20.6 

m.p.h. Reported test results indicate a change-of-velocity of 7.8 feet/second. The second 

test was conducted with a 1,840-pound vehicle impacting the signpost of 58.7 m.p.h. 

Reported test results indicate a change-of-velocity of 8.8 feet/second. Therefore, the 

tested system meets the provisions of the new, but yet unpublished, 1985 American 

Association of State Highway and Transportation Officials (AASHTO) “Standard 

Specifications for Structural Supports for Highway Signs, Luminaires and Traffic 

Signals”. We also infer this system meets the 1975 AASHTO specification since the 

1985 AASHTO specification is more demanding. 

Based on the above, the tested system is acceptable for use on Federal-aid projects if 

proposed by a State. We also infer your 7 7/8-inch square by 1 1⁄4-inch thick laminated 
veneer lumber post is also acceptable. Furthermore, only one post is allowed within an 8-

foot path. 

At the present time, FHWA has not yet adopted the 1985 AASHTO specification. Once 

the AASHTO publishes their specification, we intend to proceed with the process to 

officially adopt a new specification. We will issue a Notice of Proposed Rulemaking 

(NPRM) in the Federal Register, provide a public comment period, review and evaluate 

any comments we receive, and then issue a Final Rule. The effective date if 

implementing a new specification for Federal-aid highway work is not expected to be 

until at least mid-1987. 

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

its structural features. Presumably, Trus Joist Corporation will supply potential users 

with sufficient information on structural design and installation requirements, including 

the need to size the sign panel and support for expected wind loading, to ensure proper 

support performance. 

We anticipate that the States will require certification from Trus Joist Corporation that 

materials furnished have essentially the same mechanical properties and geometry as the 

materials used in the tests and that the support will meet the change in momentum 

requirements of the AASHTO specification. 

 Sincerely yours, 

 Norman J. Van Ness, Chief 

 Highway Design Division 

Enclosure