According to the Observer (and the MTA), a lot. CBTC upgrades will let the line operate at a theoretical capacity of 26 trains per hour, or one train every 2 minutes and 20 seconds or so (current capacity is 19 trains an hour, or one every three minutes or so). That represents a 38% increase in capacity, which is great considering the continued pace of development between Bedford Avenue and Myrte-Wyckoff.

At least until there is a sick passenger.