Re: Kolkata to Siliguri via Patna (4 lane highways only) Hi Haldar!
To go to Calcutta, you would have to come to Purnia, take a right turn at Purnia zero mile for Forbesgunj/Araria and continue towards Darbhanga/Muzaffarpur.
Till Muzaffarpur, it is an absolute blast, less traffic and proper 4 lanes with decent tarmac. Once you reach Muzaffarpur, you will have to negotiate a bit of bad roads and worse traffic to enter the Hajipur road. Initial road here doesn't have a 4 lane and traffic will tire you as well as the bad humps prior to toll & bridge will have to be carefully negotiated in the BMW.
Patna is a nightmare in itself. From Patna, there are no 4 lanes to reach GT road. You would either have to go via Gaya or via Sasaram.
I have done the exact route on 21st but not between Patna/Gaya. Roads are good but not 4 lane.
After Muzaffarpur, you might be tired & exhausted. You may drive till Lucknow and then catch the GT from there if you wish to drive only on 4 lane.
The route which I have taken & will take with a D segment sedan shortly.
Purnia - Bhagalpur - Amarpur - Deoghar - Dumka - Messanjore - Bolpur [shantiniketan] - Bardhaman - Calcutta
At Bhagalpur, there is a bypass. More here |