What should be used to track trains at Journal Square yards?

To track trains efficiently at Journal Square yards, the selection of track numbers needs to facilitate organization, spacing, and operational management of the train movements. The numbers 9, 12, 15, and 17 provide a systematic approach to spacing, which is crucial in preventing congestion and ensuring that each train can be easily monitored and managed.

These numbers suggest a configuration that supports the potential for regular train operations while allowing for clear identification of track assignments, maintenance schedules, and operational dynamics. Using even spacing within the numbering system helps signal staff regarding the specific positioning of trains within the yard, making it easier to control and coordinate movements effectively.

In contrast, the other options may not reflect an optimal arrangement for tracking trains, potentially causing confusion or overlap in train assignments. Thus, the choice of 9, 12, 15, and 17 proves to be the most effective and organized for managing train operations at the yard.