via KIR-MGR-KIUL OR via KIR-BJU will be faster and shorter route for Jan shatabdi/Fast Intercity. Waise bhi Katihar se patna ek aur intercity ki demand hai..
via BGP longer route hoga, 1 din me NJP-PNBE via BGP up-down possible nahi hoga and BGP-Patna ke bich already 3 Intercity chal rahi hai (13401,13241,13235)..