What indicates the area where vehicles must stop before entering a runway?

The area where vehicles must stop before entering a runway is indicated by runway hold lines. These lines are a critical part of the airside marking system and are designed to ensure that vehicles do not accidentally encroach upon the runway while aircraft are in operation. The hold lines are typically painted in a series of solid and dashed lines to clearly delineate the point at which aircraft and vehicle operators must yield or stop.

When approaching a runway, the visibility of these hold lines serves as a clear warning that the area ahead is controlled and potentially dangerous for unauthorized vehicles. This enhances safety by preventing collisions between ground vehicles and aircraft, ensuring that all operations around the runway are conducted in a safe manner. Overall, runway hold lines play an essential role in maintaining the integrity of air traffic control procedures at airports.