Kalyan would also be among the busiest. But IR generally accounts for suburban traffic as a separate entity. This is mainly because, though there are some locals that run on the main line tracks and some stretches where all locals share mainline tracks, by and large, suburban trains tend to run on their own dedicated corridors with their own schedules, having a small overlap with the mainline trains. Because of this, controlling for both types of traffic tends to be largely independent.
Also most of the freight traffic goes through the yard and dedicated freight lines, unlike BZA and BRC which have the freights too passing through the main station only (Some freights do bypass BZA, but freights coming from the...
more... South have no option but to go through the station).