The A Division and B Division trains operate only in their own division; operating in the other division is not allowed because the IRT sections have narrower tunnel segments, tighter curves, and tighter platform clearances than the BMT/IND sections.
The A Division and B Division trains operate only in their own division; operating in the other division is not allowed. This is mainly because the IRT sections have narrower tunnel segments, tighter curves, and tighter platform clearances than the BMT/IND sections.