AFAIK, Mumbai has a unique controlling system. So, for fast moments, without much delay, as u all know, there are diff tracks for up/down, freight and Local's.
They monitored from a unit where the data comes in live, of all trains entering these section n that helps them to communicate n transmit the data to the section, where they can inform crew what to do and what not do.
After all, in India, its one of the busiest sections, after NDLS n HWH.