Installing protected-permissive FYA operation along emergency vehicle preemption routes requires special study and consideration. Work closely with emergency vehicles to provide the preemption operation that best fits their preference. Carefully consider whether to allow or terminate FYA for the opposing left during preemption. If the opposing FYA is to be turned off during preemption, the through phases will need to be terminated (go to all red) prior to dropping FYA for preemption.

For example, consider an intersection that is displaying Circular GREEN (for through) and FYA (left-turn lane) for both approaches of an arterial. Then, preemption activates to provide a protected through and left turn (Circular GREEN and GREEN ARROW dwell phase) to the approach for the emergency vehicle. From here, there are two possible states for the opposing left-turn FYA. It may continue to flash during the preemption dwell phase or it may be terminated. If it is decided to terminate the opposing left-turn FYA, then to go to all-red prior to displaying the dwell phase.