At large stations, particularly those with originating trains, it is customary to have a shunting line for locomotives. The shunting line removes the need for blocking all platforms when a locomotive is doing shunting operations. Locos are usually parked on these lines before moving to the trip shed or being attached to another train.
As for freight traffic, NGP has a freight yard with through lines parallel to the main station on the east side. Most, if not all freight traffic, passes through that yard. The line to that freight yard is...
more... the one that forms the famous diamond intersection with the Calcutta line at NGP outer.