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                Safety Eligibility Letter LS-57r
  
  **Hardware Type:**
            Luminaire Supports
                          **Code:**
            LS-57r
                          **Date:**
            07/26/2004
                          **Testing Criteria:**
            NCHRP 350
                          **Manufacturer:**
            Akron Foundry
                          **Device Description:**
            TB1-17 breakaway cast aluminum transformer base
                          **View PDF:**
            ls57r.pdf (53.25 KB)
    
    "FHWA Logo"

**July 26, 2004**

**Refer to: HSA-10/LS-57**

Mr. Robert Sik
Vice President
Akron Foundry Company
2728 Wingate Avenue
P.O. Box 27028
Akron, Ohio 44319-0009

Dear Mr. Sik:

Thank you for your letter dated March 24 requesting Federal Highway Administration (FHWA) acceptance of a modification to your company's TB1-17 breakaway cast aluminum transformer base for use on the National Highway System under the provisions of National Cooperative Highway Research Program Report 350 "Recommended Procedures for the Safety Performance Evaluation of Highway Features."

You requested that we find the TB1-17 base acceptable when used on a 13-1⁄2 inch bolt circle with a modified stack pack washer arrangement. This change is requested to accommodate the State of Nebraska in order to retrofit existing poles (currently installed on failing frangible couplings) mounted on 13 1⁄2 inch bolt circles.

We have reviewed the results of prior crash testing of the TB1-17 bases, which had been found acceptable when used with standard round washers on bolt circles ranging from 13 inches to 15 inches, and concur that this minor modification would have no significant impact on the breakaway performance of your company's transformer bases. All appropriate conditions in the previous FHWA acceptance letters dealing with Akron Foundry cast aluminum transformer bases continue to apply.

Sincerely yours,

**/Original Signed by/**
John R. Baxter, P.E.
Director, Office of Safety Design
Office of Safety U.S. DEPARTMENT OF TRANSPORTATION

**Federal Highway Administration**

1200 NEW JERSEY AVENUE, SE

WASHINGTON, DC 20590

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