February 11, 1992

Refer to: HNG-14/SS-26

Mr. Herbert J. Henry
Telespar Product Manager
Unistrut Corporation
35660 Clinton Street
Wayne, Michigan 48184

Dear Mr. Henry:

Thank you for your letter of January 23 requesting Federal Highway Administration's (FHWA) acceptance of a modification to your company's perforated square steel tube breakaway small sign supports. Our letter of March 31, 1989, accepted a range of Telespar post sizes for use on Federal-aid highway projects. All of the supports consisted of a base post projecting 100 mm (4 inches) or less above the ground into which was inserted the signpost. Some of the assemblies included a sleeve around the base post, which is intended to reduce damage to the base post in the even of a knockdown.

The modification you desire is to omit the sleeve from those post assemblies that called for one. The reason for this change is to reduce initial installation cost for these small sign supports. We agree with your argument that the use of the sleeve would reinforce the base post which could result in favorable life-cycle costs for these sign supports. However, based upon our review or prior crash testing of square steel tube sign supports, we believe that omission of the sleeve will not significantly affect the breakaway performance of these sign support systems. Therefore, Telespar post sizes 22F12, 20F12, 16F12, and 14F12 are acceptable for use on Federal-aid highway projects with or without the “sleeve” around the base post if requested by a State. All other conditions in our previous letter remain in effect.

Sincerely yours,

L.A. Staron, Chief
Federal-Aid and Design Division

Geometric and Roadside Design Acceptance SS-26