Oh yes... I think that I had got confused with that Dhanbad Route Angle. Yes, a train that can connect Gaya and Patna in a single route is surely needed. Rather than extending this supercrowler 13131 to Gaya, IR should connect Kolkata, Gaya & Patna with a single Superfast Intercity Express train that includes Patna Saheb as a stoppage too :)
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PS: Pilgrims from Gaya's
Guru Tegh Bahadur Ji Gurudwara to Patna Saheb can use such a train for pilgrimage without changing trains.