What is the first action a control operator must take before granting track and time?

Before a control operator can grant track and time, the initial action required is to apply blocking or marking devices to the control machine. This procedure is crucial as it ensures that the track is properly protected from unauthorized movement, thereby safeguarding both the maintenance crew and the trains. Blocking or marking devices serve as physical and visual indicators that the track is under a specific authority's control, alerting other operators and crews to this condition.

By implementing these devices, the operator establishes a secure environment where work can safely proceed without interference from train movements, which are typically managed through central or local dispatching commands. This step is fundamental to maintaining safety protocols within railway operations, preventing accidents, and ensuring the integrity of both the work being performed and the passage of trains.