What is the purpose of runway crossing signals and lighting?

• A. To control the speed of ground vehicles on the taxiway.
• B. To display the airport weather information to pilots.
• C. To indicate the status of the runway occupancy to controllers only.
• D. To indicate when it is safe to cross the runway and provide visibility to pilots and ground traffic.

Answer: (D)

Runway crossing signals and lighting exist to coordinate crossing of a runway at intersections by both aircraft and ground vehicles. Their purpose is to indicate when it is safe to cross and to provide clear visibility of the runway’s status to everyone involved. This shared visual cue helps prevent runway incursions by ensuring pilots taxiing near a runway and ground personnel know when a crossing is clear and when it is not. It works in tandem with ATC instructions—when clearance to cross is given, the signals reinforce that crossing is allowed, and when it isn’t safe, the lights and signals clearly warn otherwise. It’s about informing both pilots and ground traffic, not about weather information or only informing controllers.