Union Cabinet approves construction of twin tube road and railway tunnels under River Brahmaputra in Assam with a cost of ₹18,662 crore 

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In a landmark development for infrastructure in India’s Northeast, the Union Cabinet chaired by PM Narendra Modi on Friday approved the construction of the country’s first twin-tube underwater rail-cum-road tunnel beneath the Brahmaputra River in Assam. It will be part of a 4-Lane Access-Controlled Greenfield connectivity from Gohpur on NH-15 to Numaligarh on NH-715, including a 15.79 km of Road cum Rail Tunnel.

This would be the first underwater Road cum Rail tunnel in India and 2nd in the world. The project will provide significant benefit to Assam, Arunachal Pradesh, Nagaland and other North-Eastern States. This will enhance the efficiency of freight movement, reducing logistics costs and driving socio-economic growth in the region.

At present, the region is far away from existing bridges over the Brahmaputra, and it takes hours of a road trip to visit from one side of the river to the other. The Kaliabhomora bridge on the west is around 90 km away, and the Bogibeel bridge on the east is over 150 km away from the site of the proposed tunnel site. The tunnel will drastically reduce the distance between Numaligarh and Gohpur from 240 km to just 34 km, slashing travel time by 95%, from six hours to a mere 20-30 minutes.

The tunnel will connect the two parallel national highways and two parallel railway lines that run parallel to the River Brahmaputra on both its banks.

The ambitious project entails a 33.7 km four-lane corridor connecting Gohpur on the north bank to Numaligarh on the south bank, including the 15.79 km tunnel under the mighty Brahmaputra. The project will be executed in EPC (Engineering, Procurement, and Construction) Mode.

The estimated cost for the project is ₹18,662 crore, out of which ₹11,982.36 will be civil works cost and the ₹716.65 crore has been set aside for land acquisition. As per earlier reports, the Defence Ministry will fund 20% cost of the tunnel, given its strategic importance.

Out of the two tunnels, one tube under the riverbed will handle road vehicles, while the other will be equipped for trains using ballastless tracks and electric traction. The tunnel will be built approximately 32 meters below the riverbed, addressing challenges posed by the Brahmaputra’s dynamic flow and ensuring all-weather connectivity.

Tunnel Boring Machines will be deployed for the main tunnel under the river, while the open-cut-and-cover method will be used for the sections of the tunnels on both ends. The length of the main tunnel under the river will be 11.4 km. Artificial islands will be built on the northern and southern sides of the river Brahmaputra, and the construction zone will be created within the islands to facilitate the construction of the tunnel and also during the operational phase. The islands will act as bunds to prevent floodwater from entering the tunnels.

The proposal for a tunnel was originally floated by the Border Roads Organisation (BRO), considering its strategic importance. BRO started surveys for the project in 2014 and selected two sites, Tezpur-Nagaon and Gohpur-Numaligarh. In 2020, the centre gave in-principle approval for the project, after which detailed studies were conducted, including an airborne electromagnetic survey.

Initially, the Tezpur site was favoured, as the river is narrower there, and Tezpur is home to the headquarters of the GOC 4 Corps of the Indian Army. However, later, the Gohpur-Numaligarh location was selected, primarily because the twin Kaliabhomora bridges are already present over the Brahmaputra at that place.

The centre has entrusted NHIDCL (National Highways and Infrastructure Development Corporation Ltd.) with the project, and the NHIDCL floated tenders to prepare the DPR and will start pre-construction activities in 2023.

Written by OpIndia Staff
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