The common nickname for the U.S. Pedestrian Hybrid Beacon is the HAWK beacon.
HAWK stands for “high-intensity activated crosswalk.” Unlike a conventional traffic signal, the beacon is normally dark and activates only when a pedestrian requests a crossing. Its sequence typically begins with flashing yellow, moves to steady yellow, then displays steady red to stop vehicles; the red phase later alternates, allowing a stopped driver to proceed cautiously only after yielding when the crosswalk is clear.
The first HAWK was developed and installed in Tucson, Arizona, in 2000 by transportation administrator R. B. Nassi. The design was inspired partly by Britain’s pelican crossings. It was initially treated as an experimental traffic-control device, but the Federal Highway Administration incorporated the pedestrian hybrid beacon into the 2009 Manual on Uniform Traffic Control Devices.
The name is easy to confuse with other flashing beacons, but HAWK is not a generic term for every crosswalk flasher. It specifically identifies this activated hybrid signal, whose unusual dark, yellow, red, and flashing-red sequence is designed to stop traffic only when needed.