When is an inferior train required to protect the head end?

An inferior train is required to protect the head end when it is unable to clear the main track. This requirement is put in place to ensure safety and to prevent potential accidents by providing adequate warning to other trains approaching the area. When a train cannot completely clear the tracks, it poses a significant hazard to oncoming traffic, and thus, measures must be taken to signal or protect the head end.

This protection can involve flagging or use of other signaling methods to alert nearby trains of the situation. The necessity for this protection is rooted in the operational rules aimed at maintaining safe and efficient rail operations, especially in scenarios where trains are operating close to one another on shared tracks.

The other scenarios presented, such as moving through a junction, entering a freight terminal, or being near a passenger station, do not specifically mandate protecting the head end in the event of being unable to clear the main track, as they deal with different operational protocols and may not entail the same level of risk to other trains.