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FHWA Home / Safety / Roadway Departure / Safety Eligibility Letter SS-161

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U.S. Department of Transportation
Federal Highway Administration

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

January 26, 2010

In Reply Refer To: HSSD/SS-161

Mr. Thomas Burnham
Vice President of Services
Spot Devices
1455 Kleppe Lane
Sparks, NV 89431

Dear Mr. Burnham:

Thank you for your letter of November 30, 2009, requesting the Federal Highway Administration’s (FHWA) acceptance of your company’s School Zone Flashing Beacon system mounted to a schedule 40 galvanized steel pole on a Pelco 5300 series break-away base as a crashworthy system for use on the National Highway System (NHS). Accompanying your letter was a drawing of this system (enclosed for reference) and system specifications, typical of the largest and heaviest system you offer. You requested that we find the systems 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.”

The enclosed diagram shows a common pole layout. You noted in some cases this setup will also have an additional side of pole solar panel mounted just below the top of pole solar panel, and this may take up an additional 24 inches of pole height, so the total pole height would be 17 feet. The Schedule 40 galvanized steel poles, threaded at one end, conform to ASTM A53 specifications. The diagram also shows the significant holes that would be drilled in the pole -- one 2.25-inch hole for each beacon, and four closely spaced 1.125-inch holes for the controller wiring. The height of the lowest hole will be no lower than 84 inches above the ground.

Weights of the significant components are:


Systems that Spot Devices requested acceptance for are:

You referenced three FHWA Acceptance Letters, SS-90, dated August 18, 2000, SS-143, dated November 29, 2006, and SS-155, dated October 2, 2007. These systems are similar to the Spot Devices systems in that they include signs, lights, and other hardware on breakaway poles. The Spot Devices system detailed above is heavier than the systems accepted in the letters you referenced. However, as the mass of the hardware serves to increase the center of gravity of the system, it will allow the pole to rotate over the vehicle at a higher elevation but have little effect on the performance of a crashworthy breakaway base.

Therefore, the systems described in the requests above and detailed in the enclosed drawing are acceptable for use on the NHS under NCHRP Report 350 Test Level 3 conditions when such use is acceptable to a highway agency. This acceptance will be limited to use with Schedule 40 steel poles mounted on the Pelco cast aluminum bases you referenced (FHWA Acceptance Letter B-18 dated May 5, 1992) on generic four-bolt breakaway slip bases or on a comparable breakaway base using crashworthy frangible couplings.

Please note the following standard provisions that apply to FHWA letters of acceptance:


Sincerely yours,

/* Signature of David A. Nicol, P.E. */

David A. Nicol
Director, Office of Safety Design
Office of Safety


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