the reason for the success of JP double decker is that Jaipur is visited by people all over the world (most of them chose Delhi to be the base for visiting the Golden Triangle). Also Jaipur being a state capital is much bigger and important city than Dhanbad, Asansol & Durgapur hence gets much bigger elite crowd to visit Delhi. I think this DHN double decker should be extented to Gaya so that it can benefit the tourists/pilgrims to Parasnath, Hazaribagh Gaya and Bodh Gaya.