What do two solid and two broken lines in hold short lines signify?

The presence of two solid lines combined with two broken lines in hold short lines indicates the limit line for runway crossing. These markings are crucial for maintaining safety in airside operations, as they clearly define where vehicles must hold before entering a runway area. When a vehicle encounters these lines, it must stop and ensure that it is safe to proceed, as crossing them means entering an area where aircraft may be landing or taking off.

This designation helps regulate traffic on the airside, thereby preventing potential collisions between vehicles and aircraft. Understanding this visual cue is essential for anyone operating a vehicle in the vicinity of runways, allowing for compliance with safe operating procedures.