What defines the time when an employee is actively engaged in duties related to train movement?

The correct choice is defined as the period when an employee is actively engaged in activities that are essential to the operation and movement of a train. This includes tasks such as monitoring train safety, managing passenger flow, and communicating with other crew members and dispatchers to ensure that all aspects of train operation are functioning smoothly.

This term is significant within rail operations because it outlines the responsibilities and the active commitment required from personnel during their work to ensure efficient and safe transport services. The designation of this timeframe ensures clarity in scheduling, compensation, and accountability for the personnel involved.

In contrast, other options refer to different states of duty. "On Duty Time" generally signifies any period an employee is formally scheduled to work, which might encompass both active and inactive periods. "Limbo Time" often refers to a status where an employee may not be actively engaged but is not formally off duty, while "Off Duty Time" clearly indicates times when employees are not working and are relieved of their duties altogether. Hence, "Covered Service" accurately captures the essence of active engagement when handling train operations.