When may a main track switch be returned to normal position if a train is leaving the track?

The appropriate moment to return a main track switch to its normal position is when the equipment has passed the clearance point of the track. This ensures that the switch is not inadvertently activated while a train is still in the area of the switch, which could lead to unsafe conditions or accidents. The clearance point is a designated location that indicates the minimum distance a train must travel to ensure it is safely clear of the switch before it is returned to its normal position.

Returning the switch too early could result in a train still potentially in the vicinity being diverted onto another track, risking collision or derailment. Therefore, it is critical to wait until the equipment is fully beyond this point to ensure safety and maintain efficient train operations.