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Interpretation Letter 4(09)-22(I) - Flashing Pattern for Existing RRFBs

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U.S. Department of Transportation
Federal Highway Administration

1200 New Jersey Avenue, SE.
Washington, D.C. 20590

August 8, 2012

In Reply Refer To: HOTO-1

Mr. William M. Marshall
Chief Executive Officer
Electrotechnics Corporation
1310 Commerce Street
Marshall, TX 75672

Dear Mr. Marshall:

Thank you for your letter of July 11 requesting an official interpretation regarding the flashing pattern for Rectangular Rapid Flashing Beacons (RRFBs) that were in existence prior to the issuance of official Interpretation 4(09)-21.

We recognize that there were already a significant number of RRFBs in existence when we issued a new official interpretation regarding the required RRFB flashing pattern in June 2012. These RRFBs were installed or manufactured based on the flashing pattern described in the original Interim Approval 11 memorandum dated July 16, 2008, or based on the flashing pattern described in official Interpretation 4(09)-4 dated August 3, 2010.

It is the FHWA's official interpretation that the flashing pattern requirements that are contained in our Interpretation 4(09)-21 dated June 13, 2012, do not apply to any RRFBs that were installed or shipped to a customer prior to July 6, 2012, which was the date that Interpretation 4(09)-21 was added to the MUTCD web site. In other words, there is no requirement to modify the flashing pattern of RRFBs that were in existence on July 6, 2012 to comply with the flashing pattern requirements that are contained in Interpretation 4(09)-21.

For recordkeeping purposes, we have assigned the following official ruling number and title: "4(09)-22 (I) — Flashing Pattern for Existing RRFBs." Please refer to this number in any future correspondence regarding this topic.

Thank you for your interest in improving the clarity of the provisions contained in the MUTCD.

Sincerely yours,

Original signed by:

/s/ Chung Eng for

Mark R. Kehrli
Director, Office of Transportation Operations