A rectangular rapid flashing beacon (RRFB) is a type of yellow flashing beacon used at pedestrian, school, or trail crossings that flashes only when activated by a pedestrian through use of a push button. The rapid flashing pattern provides emphasis and substantially increases driver yielding rates at crossings. While at this time there are only a few RRFBs in service on the state highway system there are a number on local streets.
RRFBs are currently under interim approval by the FHWA but are expected to be included in the next edition of the Manual on Uniform Traffic Control Devices which is to be issued by May 2023.
For additional information see the Interim Approval Memorandum IA-21.