RFB…and that means?

RFB means Rapid Flash Beacon. See the link below for a visual. These are usually placed at marked crosswalks on very busy streets where there is no traffic signal to stop traffic. They are implemented where it is difficult for pedestrians to cross the street safely.
What’s the law surrounding these? In a nutshell it’s this: when these lights are activated by a
pedestrian desiring to cross the street there is no legal requirement for a motorist to stop UNLESS the pedestrian has prudently placed his/her foot into the street prior to that vehicle’s approach of the crosswalk. (this is how a pedestrian establishes right-of-way in all 50 states and D.C.) Technically, these flashing beacons are traffic control devices with NO legal punch.
In other words, they’re just there to raise awareness that a pedestrian is trying to cross the street safely. Be a sport, hit your brakes.