A Track Authority in CTC Territory includes the instruction Switch No (SW-N) at the entrance point of the limits. What further authority do you require to enter the limits?

• A. Verbal authority from the control operator to enter the limits
• B. No further authority
• C. Written permission
• D. A flag signal

Answer: (A)

In CTC territory, moving into a defined limits requires explicit entry authorization from the control operator, not just the route indication. Even though the instruction about Switch No (SW-N) shows the route is prepared at the entrance, you still need verbal clearance from the control operator to enter the limits. This verbal permission confirms that the dispatcher has verified the block ahead is clear and that your movement is authorized to proceed, coordinating with other potential movements.

Verbal authorization is the standard method for entering a controlled block because it provides a direct, real-time confirmation from the person managing the movement plan. Written permission isn’t used for routine entry in this context, and flag signals aren’t relied on in modern CTC operations. The SW-N instruction sets up the route, but the entry authority comes from the control operator’s verbal instruction.