When must a train proceed prepared to stop at the interlocking signal while approaching an automatic interlocking?

The correct answer indicates that a train must be prepared to stop at the interlocking signal while approaching an automatic interlocking when it is moving below 25 mph and passing a signal that governs the approach. This is essential for safety and operational efficiency in railroad operations.

When a train is approaching an automatic interlocking, it is critical to be vigilant about signals that indicate the status of the track ahead. If the train is moving below 25 mph, it allows for a more controlled and safer manner of stopping if necessary when encountering an approach signal. This scenario usually indicates that there may be conditions that require the train to be prepared to stop, such as the presence of conflicting routes or the need to clear the interlocking for another train.

Being prepared to stop at these signals ensures that trains do not inadvertently enter a situation that could lead to collisions or operational disruptions. This practice reflects adherence to safety protocols designed to protect both train crews and passengers, as well as facilitate smooth train movements in complex rail environments.