What action must occur when a track bulletin Form B is implemented?

When a track bulletin Form B is implemented, the primary action required is that the train must not make further movement unless instructed. This is crucial because Form B indicates that there are restrictions or changes in the track conditions that the train crew needs to be aware of. It signals that an unsafe condition may exist on the track ahead, and therefore, the crew must halt any further movement until they receive specific instructions on how to proceed safely.

This reflects the emphasis on safety within rail operations, ensuring that all crew members are fully informed of potential hazards before continuing. The rule is fundamental for maintaining operational safety, as it prevents possible accidents or derailments that could occur if a train were to move without the necessary guidance in the context of implemented track restrictions.