When does the ATC system request train length confirmation?

The ATC system requests train length confirmation when there is uncertainty about the train's length. This is crucial for the safe operation of the train, as knowing the exact length allows for proper accounting for stopping distances, signal clearances, and other safety considerations. Ensuring that the system has accurate information about the train's length helps prevent potential safety hazards that could arise from miscalculations or assumptions regarding the train's dimensions.

Confirmation of train length is especially important in situations where multiple trains may be operating on the same track or where specific signal indications may be influenced by the train's size. By prompting for this information when there is uncertainty, the system enhances safety protocols and mitigates risks associated with incorrect assumptions about train length.