A Tower Operator operating an Interlocking Machine with a Traffic Control feature can normally change the direction of traffic ONLY when?

The correct choice, indicating that a Tower Operator can normally change the direction of traffic only when the track is unoccupied, is grounded in safety protocols and operational guidelines. When the track is clear of trains, it minimizes the risk of accidents or collisions during the switch of traffic direction. Ensuring that the track is unoccupied allows the operator to confirm that changing the traffic direction will not interfere with ongoing operations, thus maintaining a safe environment for both trains and personnel.

In contrast, the other options involve aspects that contribute to operational integrity, but they are not the primary condition for changing traffic direction. Signals being in the clear position indicates readiness for movement but does not guarantee safety if a train occupies the track. Acknowledged previous commands ensures a smooth workflow but does not equate to a guarantee of track safety. Completing a reset protocol may be necessary for machine functionality, yet, without confirming that the track is unoccupied, it does not provide the means for safe traffic direction changes. Overall, prioritizing track occupancy is essential for safe operations in railway management.