India is set to build its first twin-tube underwater tunnel carrying both road traffic and trains beneath the Brahmaputra River in Assam, marking a boost to infrastructure in the Northeast.

An inter-ministerial committee led by the Expenditure Secretary has given 'in-principle approval' to the project linking Gohpur and Numaligarh. The 15.8 km tunnel will anchor a 33.7 km corridor with approach roads and a railway line. One tube will carry a single electrified, ballastless rail track, with road traffic halted during train movement, while the second tube will serve road vehicles with two unidirectional lanes. Built about 32 mtrs. below the riverbed, the tunnel is designed for faster military deployment and civilian travel.

Journey time is expected to fall from over six hours to around 30 minutes, shrinking distance from 240 km to 34 km. The Rs 18,600 crore project may be completed within five years after Cabinet approval, before Assam elections.