Nitish, 15941 Jhajha Dibrugarh Express departs from Jhajha on Fridays at 22.05 hrs and halts at Durgapur for 20 mns from 2.45 to 3.05 am, where the normal halt for trains varies from 2 to 4 mns. Enough stoppage time to suggest a loco reversal. The same timings at Durgapur are applicable for 15661 Ranchi Kamakhya Express and 15639 Puri Guwahati Express.
The next stoppage for all these 3 trains is Siuri at 4.32 am which clearly indicates that they reverse direction at Durgapur and traverse the Durgapur-Andal- Siuri route and not via the Khana bypass. (Source: East Zone timetable wef July 2011)