I agree of u saying that space might be a constraint towards the west side of station building coz of dat road and building. But there is ample space to the east side of the station building i.e towards the existing bhanugudi fly over, where the 4th pf can be extended beyond the 3rd pf such that it length cater to 20-21 coaches.
And its good if something turns out and materializes finally in expansion of yard.