What criteria must be met to keep the main track switch open in TWC territory?

In TWC (Track Warrant Control) territory, one of the critical safety protocols is that main track switches are only permitted to remain open when they meet specific criteria. The correct answer emphasizes the need for authorization by track warrant. This requirement ensures that train movements are coordinated and controlled, preventing accidents and ensuring the safety of both train crews and track workers.

When a switch is left open without the proper authorization, it can lead to unauthorized train movements onto tracks that are not clear, potentially resulting in derailments or collisions. The track warrant system provides a formalized method of ensuring that all movements are accounted for, with responsibility assigned to the conductor or engineer for any encroachments onto their designated track sections.

While other considerations, such as personnel clearance and maintenance, are undoubtedly important for overall safety and efficient operations, they do not specifically address the critical administrative oversight required to ensure trains can safely operate on that track segment. Thus, the requirement for authorization by track warrant is a fundamental aspect of maintaining safe operations in TWC territory.