What should be done if the track is clear but a train is delayed at an interlocking signal?

The correct action when a train is delayed at an interlocking signal while the track is clear is to proceed as per the last signal received. This means that the train crew should follow the signal indications that were in effect prior to the delay.

Adhering to the last signal is crucial because it maintains safe railway operations and ensures that the train continues to operate within established safety protocols. The railroad signaling system is designed to provide guidance based on the current status of the track and other trains in the vicinity. If the last signal was clear, indicating that it is safe to proceed, then there is no reason for the train to remain stationary if the track is indeed clear.

The other choices do not align with the operational guidelines in this context. Waiting for the next train could unnecessarily delay operations, and continuing to the next station without clear instructions could lead to unsafe situations, especially if signals change or the status of the track changes unexpectedly. Returning to the previous point would also not be necessary unless specifically instructed or in case of an emergency, which is not indicated in this situation. Following the last signal ensures that operations continue smoothly and safely.