Which statement best describes a train’s authority under a track warrant?

The accurate description of a train’s authority under a track warrant is that it extends to but does not include the last siding switch. This means that while a train has permission to operate within specific limits granted by the track warrant, it must be aware that its authority ends right before it reaches the last siding where the track switches to another line or onto a siding. Understanding this is crucial for safe and effective train operations, as it helps ensure that trains do not improperly occupy areas that could conflict with other trains or create hazardous situations.

The other statements do not correctly convey the nature of a track warrant. For instance, the assertion that a train's authority is unlimited within designated limits overlooks the precise boundaries established in the warrant. Similarly, the idea that authority is only valid while the crew is in contact with dispatch implies a constant need for communication that is not a requirement of the track warrant itself. Lastly, mentioning that the authority applies only during severe weather conditions suggests a context-specific applicability that does not accurately represent the standard operating procedures related to track warrants. Rather, the authority delineated in a track warrant is consistent regardless of weather, provided the conditions do not impact safety critical operations.