I dont know real reason why last 30km doubling of SBG loop between Bhagalpur and Kahalgaon 30 km section going very slow, Even where there is no bridge between bhagalpur jn to Lailakh Mamalkha the 14 km section out of 30km total,ground work was completed last year only no hurdles at all then also laying down of sleepers and track are going very slowly,One development at bhagalpur jn can be seen that they has started laying sleeper for 2nd dedicated line for kahalgaon side from bhagalpur jn,But target of march 2018 has already past, december 2018 will also be difficult to achieve if work goes at this rate.