Federal Highway Administration
400 Seventh St., S.W.
Washington, D.C. 20590
June 13, 2006
Refer to: HSA-10/SS-138
Mr. Gary Lamolinara
Special Lite Products Company
1634 Latrobe-Derry Road
Loyalhanna, Pennsylvania 15661
Dear Mr. Lamolinara :
Thank you for your letter of March 28, 2006, requesting the Federal Highway Administration's (FHWA) acceptance of your company's smooth wall aluminum poles as breakaway sign supports for use on the National Highway System (NHS). Based on tests of generic supports by others, you requested that we find smooth 3 inch diameter poles acceptable for use on the NHS under the provisions of the National Cooperative Highway Research Program (NCHRP) Report 350 "Recommended Procedures for the Safety Performance Evaluation of Highway Features."
Testing of sign supports follows the guidelines contained in the NCHRP Report 350, Recommended Procedures for the Safety Performance Evaluation of Highway Features. Requirements for breakaway supports are those in the American Association of State Highway and Transportation Officials' (AASHTO) Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic Signals.
Smooth, thin walled aluminum sign supports have been found acceptable in the following FHWA acceptance letters:
SS-15 dated December 12, 1989, regarding a test on a 3-inch OD 3/16-inch wall using 6061-T6 alloy.
SS-28 dated May 26, 1992, regarding tests on 3-inch OD 3/16-inch wall using 6061-T6 alloy.
SS-76 dated January 9, 1998, regarding tests on 3-inch OD 1/8-inch wall using 6063-T6 alloy.
Velocity changes on the referenced crash tests were all within acceptable limits.
Two of the test programs used poles extruded from 6061-T6 aluminum and one used 6063-T6 aluminum. Your request was for 3-inch OD poles of 6063-T6 aluminum, which has approximately 22 percent less strength than the 6061-T6 material. In addition, the wall thickness of your poles is less than the tested poles. By extrapolation we can concur in your assertion that your company's 2.950-onch OD poles x 0.095-inch wall described above and shown in the enclosed drawing for reference meet the FHWA breakaway criteria and are acceptable for use as test level 3 devices on the NHS under the range of conditions the other generic poles were tested, when proposed by a State. Neither weakening holes nor soil plates appear to be necessary.
Please note the following standard provisions that apply to the FHWA letters of acceptance:
/original signed by /
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety
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