What should trains operating on an out-of-service track ensure regarding automatic highway crossings?

The correct choice underscores the importance of safety at automatic highway crossings when trains are operating on an out-of-service track. Trains must confirm that the warning devices—such as lights, bells, and gates—have activated and operated for a sufficient period, typically at least 20 seconds, prior to proceeding. This precaution is critical because it ensures that any vehicles or pedestrians are adequately warned of the approaching train, thereby minimizing the risk of accidents.

The requirement for the warning devices to have operated for a specific time helps to ensure that motorists and others near the crossing are aware of the train's presence in time to react appropriately. This practice reflects the general safety protocols established to protect both train operators and the public, particularly in scenarios that may involve emergency maintenance or unusual operations on tracks that are usually not in service.

Maintaining heightened awareness around automatic highway crossings, especially on out-of-service tracks, is essential for preventing incidents that could lead to serious injuries or fatalities. Therefore, checking the operation of warning devices aligns with the fundamental safety objectives within railway operations.