Do you know what CBTC is?
It's a technology that would allow trains to be closee to another but still maintain safe distances, much better than the current block system allows. This ultimately leads to more TPH.
Safe distances are determined by the distance it takes a train to come to a complete stop and the distance from a train to the one in front of it. The signal system does not enter into the equation.
The BRT used a conventional block signal system on the Brooklyn Bridge that permitted 66 tph operation between Park Row and Sands St. This is 50% more capacity than any existing or proposed CBTC system.