What action should be taken if there is a main track obstruction while returning to a detached portion?

Making a return movement at restricted speed is the appropriate course of action when encountering a main track obstruction while returning to a detached portion. This approach ensures safety by allowing the train to operate in a controlled manner, providing the crew with adequate time to react to any unexpected obstacles or situations that may arise. Operating at restricted speed means that the train must be able to stop within half the distance of what is visible ahead, which significantly reduces the risk of accidents or collisions when navigating around obstructions. This protocol is essential in maintaining safe operations on the railway and mitigating potential hazards.