When can movement past a stop signal begin?

Movement past a stop signal can begin after the dispatcher explicitly communicates permission with the message, "You may proceed." This response emphasizes the critical role of dispatcher authority and communication in railway operations.

The dispatcher has the responsibility for ensuring safety and adherence to operational protocols. When they grant permission, it signifies that all safety checks have been accounted for, and conditions are clear for the train to move past the stop signal. It is vital that such commands come from a qualified dispatcher to minimize the possibility of accidents.

In contrast, the other options focus on different conditions that may not necessarily apply universally across all situations. Simply coming to a complete stop does not automatically grant permission to move, as the signal system and dispatcher communications are designed to ensure safety before any movements occur. While a visual signal from the engineer indicates readiness, it does not serve as formal authorization to proceed. Lastly, a signal changing to green generally would denote that it is safe to proceed but may still require confirmation from the dispatcher, especially in complex operational environments.