Maine dekha Hua ha Bihar me bahaut sari trains k sleeper/3A,2A coaches ka base DHN rehta ha specifically Jo Patna,BJU based trains ha..khaskar RJPB/BANKA EXP ka..uske to 60% bogie to dhn based the...aachi bogie Patna wale rakh lete aur faltu bogie ko DHN bhej dete ha