Actually this should be the logical explanation , but the problem with that is that the train actually picks up pace once its crosses the Selimpur railgate, passes through the slum dwellings at a fairly good pace and begin slowing down at Dhakuria home signal, if ofcourse the DHK Home signal is clear....
The trains crawls for the entire stretch where it runs parallel to the Jadavpur University Campus, hence my bewilderment!