But it is impossible to do OT in the section of NDLS and SBB/GZB as there is no sideline and as of my knowledge no pass though train at GZB coming from NDLS/DLI side is allowed to stop at GZB to get OT by any high priority train as GZB is too busy station. As per my travelling Experience in Poorva (12304/82) OT by Rajdhani's/ high priority train is done at DER or after DER station. when OT is done at DER it make unscheduled halt of 1:00 hours to 1:30 hours depending on nos of OT is going to happen Usually OT is done by 4 rajdhani's , 1 Garib rath and 1 superfast Trains