What do stop bars consist of at runway holding positions?

Stop bars at runway holding positions consist of steady burning red lights. These lights play a crucial role in ensuring safety by providing clear visual cues to pilots and ground vehicle operators at airports. The steady burning red lights indicate that the vehicle or aircraft must come to a complete stop before proceeding, effectively preventing inadvertent incursions onto active runways where aircraft may be taking off or landing.

In the context of airfield safety, the use of steady burning red lights is intended to establish a clear boundary that should not be crossed without proper clearance. This differentiation is vital in high-traffic environments like O’Hare Airport, where maintaining situational awareness is key to preventing accidents.