As you might have observed in few cases, BBS Raj OT the Howrah Raj due to the later's stoppage at ALD. In that case, why doesn't IR start HWH Raj from 1645 hrs instead of 1655 hrs[creating a buffer of extra 10 minutes] or better yet, withdraw the stoppage of HWH Raj and give it to SDAH Raj[It starts a good 30 mins before HWH Raj, so there is a good buffer time; plus pax from ALD will most likely book upto Kolkata in which case it will make no difference to them which Raj stops and which skips].