Exact reason nahi pata
But sune hain ki subah isko Howrah mein slot nahi milta thha isiliye Santragachi khulti hai
Pehle Dhauli exp aur Rupashi Bangla combined run karti thhi Howrah se Kharagpur, fir Dhauli apne raste aur Rupashi apne raste nikalti thhi Kharagpur se