What is the correct action if the light used to signal disappears?

When the light used to signal disappears, the appropriate action is to stop movement immediately. This is critical for maintaining safety on the tracks, as the disappearance of a signal can indicate a potential hazard or that the track is no longer clear. Stopping ensures that the train does not inadvertently move into a situation where there might be obstacles or conflicting movements that could lead to an accident.

Taking immediate action to halt movement provides time to assess the condition of the track and the signals. It allows for the possibility of contacting the relevant authorities or control centers to clarify the situation regarding the signal. Furthermore, stopping also prevents any potential violations of operating procedures that could arise from continued movement without a valid signal indication. Overall, pausing when a signal disappears is a fundamental safety measure in rail operations.