Under what condition can equipment be left without fouling another track?

The correct choice relates to the positioning of equipment in relation to the fouling point of a switch. When equipment is beyond the fouling point of the switch, it ensures that it does not interfere with the movement of trains on an adjacent track. The fouling point is defined as the location at which equipment may obstruct a track, and being beyond this point means that the equipment is clear of any potential interference with train operations.

This principle is essential for maintaining safe operations on rail networks, as it allows for effective use of track space while minimizing delays or accidents. Ensuring that equipment is beyond the fouling point guarantees that other trains can operate safely on the nearby tracks without the risk of collision. This clear positioning is crucial during both regular operations and situations where equipment is waiting on the track.

In contrast, the other scenarios presented would pose risks of fouling or obstructing track usage. For instance, having equipment on a main track that fouls a siding would directly cause conflicts with train movements. Equipment solely on a siding may still pose issues if the siding is designed to allow for movement to a main track. Additionally, leaving equipment when not in use for maintenance does not necessarily address its position relative to fouling another track, potentially leading to unsafe conditions