Keeping the traveling public, regardless of the mode of transportation, moving in a safe and efficient manner is a significant responsibility of the ACHD. The Flashing Yellow Arrow (FYA) signal is one method designed to assist in keeping traffic moving. But how does it work? This video explains how the FYA is intended to work. With over 550 traffic signals, flashing beacons, pedestrian crossings and school flashers throughout Ada County, everyone needs to stay alert and aware.