What should a train do if it encounters a stop-block signal at restricted speed?

When a train encounters a stop-block signal while operating at restricted speed, the proper action is to pass at restricted speed if permitted. Restricted speed is defined as a speed that allows the train to stop within the distance that is visible to the engineer, especially in situations where there could be obstructions or other trains on the track.

In this context, passing a stop-block signal at restricted speed means that the train must be cautious and alert to the surrounding conditions. This approach allows for the possibility of safely navigating the situation while still maintaining control over the train's movements. If an engineer were required to stop at every signal indiscriminately, it could lead to unnecessary delays and operational inefficiencies.

This answer emphasizes the importance of adhering to the operational rules regarding signals, ensuring safety remains a priority, while also allowing the train to proceed when it is safe to do so. The other options do not align with operational standards and safety protocols. For instance, stopping immediately and awaiting instructions may not be practical in all scenarios, while ignoring the signal simply disregards safety regulations. Thus, passing at restricted speed is the most responsible and appropriate course of action in this situation.