Why must signals affecting the movement of your train be observed until passed?

The chosen answer emphasizes the importance of continually observing signals until they are passed because signals can change due to various operational factors, such as the approach of another train or the actions of a dispatcher. By maintaining vigilance on the signals, crew members are able to stay informed about any adjustments that might impact their train's movement.

Monitoring signals provides crucial real-time information that helps ensure the safe operation of the train. If signals change, it affects the speed, route, and overall safety measures that the crew must follow. For instance, a signal indicating a stop might switch to proceed, or vice versa, which would require immediate action or adjustment from the crew.

While compliance with safety regulations, providing additional warnings, and monitoring speed changes are important aspects of safe train operations, the immediate necessity of observing signal changes directly relates to operational safety and situational awareness in a dynamic environment.