wats d need for a slack?
Train's passing time from BVI was 1712hrs but DC-AC conversion, increase of turnout speed at BCT from 10 to 15kph and removal of 50kph PSR at Mahim the train use to pass BVI by 1709-10hrs.
After halt, the train easily reaches BVI around 1710-11hrs but due to poor TT making it has to wait till 1715hrs for scheduled departure. The TT at BVI shuld be 1710-12hrs. Thus the dept time from BVI wuld be same as passing time of King before halt came into force. Only 1-2min...
more... will be lost in acceleration which again can be overcomed as PSR of 100kph is also removed at DRD. (correct me if DRD PSR thing is wrong).
If u see TT of most exp/SF trains coming from BCT, they have no slack at all between BCT-BVI and TT is kept such a way that rarely they will come before time and waste time halting for extra time.