Safety Eligibility Letter LS-71

U.S. Department of Transportation
Federal Highway Administration

1200 New Jersey Ave. S.E.
Washington, D.C. 20590

January 31, 2011

In Reply Refer To: HSST/LS-71

Mr. Robert Sik
Akron Foundry Company
P.O. Box 27028
Akron, Ohio 44314

Dear Mr. Sik:

This is in response to your letter of December 13, 2010 requesting the Federal Highway Administration’s (FHWA) acceptance of a common modification to a number of your cast aluminum transformer bases. You wish to modify the top bolt circle of your crashworthy transformer bases to a pattern other than what was originally tested. You accomplish this by welding a 3/4 thick plate with the revised bolt pattern to the tops of these bases.

Because all of the breakaway features are in the lower portion of these transformer bases, we concur that modifying the top will have no significant affect on crash performance. As long as the new plate is securely welded to the top, and the bottoms are identical to bases tested and accepted, they will still be considered acceptable for use on the National Highway System. The following chart summarizes the FHWA acceptance letters that address these bases.

LS-14	May 30, 1990	Valmont Industries	Cast Al transformer base No. 0283093 15 inch bolt circle	Transformer Base
LS-17	August 6, 1990	Akron Foundry	CS-300 and CS-370 Al Transformer Bases (tests of Feralux bases)	Transformer Base
LS-18	August 6, 1990	Akron Foundry	F-1300 and F-1302 Al Transformer Bases (tests of Pole Lite bases)	Transformer Base
LS-19	August 6, 1990	Akron Foundry	TB-3-17, TB-5-9, TB-6-9 Transformer Bases, 11.5 to 15.5" BC	Transformer Base
LS-22	September 19, 1990	Akron Foundry	Chart summarizing approval letters LS-2, LS-4, LS-9, LS-15, LS-19	Transformer Base
LS-58	February 8, 2005	Akron Foundry	Addition of Stack Pack washers to TB1-17	Transformer Base
LS-61	December 15, 2006	Akron Foundry	Revised bolt circle on Akron Foundry TB-6-9	Transformer Base
LS-62	December 15, 2006	Akron Foundry	Revised bolt circle on Feralux CS-300	Transformer Base
LS-63	December 15, 2006	Akron Foundry	Revised bolt circle on Pole-lite F-1300	Transformer Base

Enclosed for reference please find a set of drawings representing this condition which would be true for your complete line of bases. All previous conditions contained in the acceptance letters remain in effect.

Sincerely /* Signature of Michael S. Griffith */ Michael S. Griffith Director, Office of Safety Technologies Office of Safety

Enclosures