When can a train be authorized to proceed through overlapping track warrant limits?

A train can be authorized to proceed through overlapping track warrant limits when all trains are authorized to proceed in the same direction because this ensures safe operation within the overlapping limits. By having all trains moving in the same direction, it minimizes the risk of head-on collisions or other potential conflicts between trains. This practice is crucial in maintaining safe distances and ensuring that visibility and communication protocols are followed.

In the context of overlapping track warrant limits, it is essential for trains to have coordinated movements. The requirement for trains to proceed in the same direction ensures that there are established rules and signals for communication and movement, which allows train crews to anticipate each other's actions. This helps maintain safe operations and ensures that safety protocols are adequately observed.

The other options do not address the fundamental principle of safe train movements through overlapping track warrant limits. For instance, having only one train on the track does not necessarily facilitate the safe and orderly movement of multiple trains that might operate within proximity in other circumstances. Operating at full speed might not account for necessary safety measures that must be adhered to when trains enter overlapping limits, and whether a train has cargo does not influence the procedural requirements for safely navigating through overlapping territories.