Crossing the river at one of its widest points, the proposed 12-15km tunnel will be located 22m beneath the river bed and will have twin-tubes, each with two traffic lanes. In addition to giving the Indian army unhindered vehicle movement in a highly sensitive area, the tunnel will also reduce the travel time between Assam and Arunachal Pradesh. With costs estimated up to US$680m, the tunnel section will link to 18km of approach roads and will be built by the Indian army.

The Brahmaputra River flows through Tibet, India and Bangladesh, emptying into the Bay of Bengal. It is India’s widest river, with a channel that can be up to 18.6km at the widest.