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August 22, 1999

Refer to HMHS/SS-22A

Kurt J. Koch, PE
Senior Engineer
Trust Joist McMillan
2600 East Amity Road
Boise, Idaho 83716

Dear Mr. Koch:

This is in reply to your May 20 letter to Mr. Nicholas Artimovich of my office requesting that we acknowledge your breakaway signposts as meeting the crashworthiness guidelines contained in National Cooperative Highway Research Program Report 350 "Recommended Procedures for the Safety Performance Evaluation of Highway Features." We previously accepted your company's Type "L", Type "M", and Type "M-Modified" in our letters of August 19, 1986, and January 4, 1990. These breakaway posts were accepted under the criteria of the 1985 AASHTO "Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals". In 1993, FHWA adopted the test and evaluation criteria in NCHRP Report 350. Because Report 350 acceptance criteria are slightly less demanding that were the criteria in the 1985 or 1994 Support Specifications or the Report 230 guidelines, breakaway hardware meeting these earlier criteria do not have to be re-qualified to be accepted under Report 350 criteria.

Therefore your company's breakaway wooden sign supports which were found acceptable in the letters referenced above are considered crashworthy according to the criteria in NCHRP Report 350 and may be used on the National Highway System routes where breakaway features are required, and are requested by a State. All conditions stated in the referenced letters remain in effect. This letter is a supplement to both letters and carries the designation "SS-22A".

Sincerely yours,

Dwight A. Horne, Director
Office of Highway Safety Infrastructure


cc: Rader - HMHS, Chron - Rm 3407
Nartimovich - HMHS

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