What must a train have in order to pass a Stop Signal?

To pass a Stop Signal, a train must obtain verbal permission from the Dispatcher. This protocol ensures safety and coordinated movement on the railway, as a Stop Signal indicates that there's a condition preventing the train from proceeding. By obtaining permission, the train crew is confirming that it is safe to move past the signal, taking into account any potential conflicts with other trains or track conditions.

The requirement for verbal permission emphasizes communication and authority in railway operations, underscoring the importance of clear directions from the Dispatcher, who has the oversight of train movements and can provide vital information about the status of the track ahead. The other options do not align with established safety practices: written permission from the Engineer wouldn't meet the immediacy required in such situations, prior conditions do not negate the need for explicit permission, and automated clearance based solely on timing doesn't sufficiently address safety protocols in active train operations.