This reminds me of a tangentially related fact that I saw a DBRT bound train when at Guwahati. It nearly completely emptied there at morning. AC coaches, SL and one could find a window seat even in General. I thought it maybe because the train is late but nope, it was more or less on time. Apparently, the rail line loops around to Dibrugarh whilst the road route is just faster so unless, it's an overnighter or a really fast train, folks just prefer the road route towards Dibrugarh over trains.