Effective December 21, 2017, FHWA rescinded the MUTCD - Interim Approval for Optional Use of Rectangular Rapid Flashing Beacons (IA-11). As a result, no new installations of RRFBs are
permitted. Installed RRFBs may remain in service until the end of the useful life of those devices and need not be removed. Contact the Bureau of Maintenance and Operations for issues regarding
RRFBs at (717) 787-9787. FHWA Memorandum: MUTCD - Interim Approval for Optional Use of RRFBs (IA-11) - TERMINATION (12/21/17)
FHWA Policy Memorandum: https://mutcd.fhwa.dot.gov/resources/interim_approval/ia11/fhwamemo.htm