Exchange karne ke liye hoga.. one memu comes as SJN-VR and other as PNVL-DRD at night. So VR wali ko DRD bhej ke next change karte honge.. MEMUs are based at BRC. To VR-SJN and onwards chain se shed return. Maine bhi first time dekha.. i always thought ki SJN-VR returns as VR -SJN in morning, rake being at Vr whole night.