What does a lighted operator's indication inform train operators about?

A lighted operator's indication primarily informs train operators about the status of the train's side doors. When the indicator is lit, it signals that all side doors are securely closed, which is crucial for safe train operation. Ensuring that the doors are closed protects passengers from potential hazards as the train moves. This information is particularly relevant during station stops, as operators need to confirm that it is safe to depart before the train begins to move.

Other options, while related to train operation, are not the specific focus of a lighted operator's indication. Train speed adjustments are managed through different systems and signals, while track conditions are conveyed through various external systems and alerts. Similarly, passenger announcements are typically made through the train's public address system and do not relate to the door status indicated by a light. Understanding these indicators helps operators maintain safety and operational efficiency.