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FHWA Highway Safety Programs

Safety Eligibility Letter SS-56A

Hardware Type:
Sign Supports, Mailboxes, and Delineator Posts
Code:
SS-56A
Date:
Testing Criteria:
NCHRP 350
Manufacturer:
Marion Steel Company
Device Description:
Modify design to use "bar spacer"
View PDF:
ss56a.pdf (114.08 KB)
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March 14, 1996

Refer to: HNG-14/SS-56A

Mr. Rick Mauer
National Sales Manager
Marion Steel Company
912 Cheney Avenue
Marion, Ohio 43302

Dear Mr. Mauer:

This is in response to your March 4 letter to Mr. Jerry L. Poston, former Chief of the Federal-Aid and Design Division. You requested the Federal Highway Administration's acceptance of a modification to your company's Lap Splice breakaway system for Rib-Bak u-channel sign supports. The unmodified version of the Lap Splice system was found acceptable for up to three 5.9 kg/m u-channel posts within a 2.1 meter span by our Geometric and Roadside Design Acceptance Letter SS-56 dated July 13, 1995.

The proposed modification would replace the threaded spacers used with each of the two connecting bolts with a single bar of steel, drilled and tapped with threaded holes 4 inches (102 mm) apart. The spacer bar will be 3/8-inch (9.5-mm) thick, as were the individual spacers used in the crash tests. A drawing of the Lap Splice bar spacer is enclosed.

We concur that the spacer bar will cause no significant change to the breakaway performance of the lap Splice system and that no additional crash testing will be required. Therefore, your company's breakaway Lap Splice system with the spacer bar will be acceptable for use on the National Highway System when requested by a State. All other conditions in our July 13, 1995, letter remains in effect.

Sincerely yours,

Seppo I. Sillan, Acting Chief
Federal-Aid and Design Division

Enclosure

Supplement to Geometric and Roadside Design Acceptance Letter SS-56A

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