What Happened
- The Cabinet Committee on Economic Affairs (CCEA) approved the construction of India's first twin-tube underwater road-cum-rail tunnel beneath the Brahmaputra River in Assam at a cost of Rs 18,662 crore.
- The 33.7 km greenfield corridor will connect Gohpur (NH-15) to Numaligarh (NH-715), including a 15.79 km twin-tube tunnel built using Tunnel Boring Machine (TBM) technology.
- The project will reduce the travel distance between Gohpur and Numaligarh from approximately 240 km (via the Kaliabhambhora bridge near Silghat) to about 34 km, cutting travel time from nearly six hours to a fraction of that.
- The corridor is expected to generate approximately 80 lakh man-days of direct and indirect employment and enhance connectivity to Arunachal Pradesh, Nagaland, and other northeastern states.
Static Topic Bridges
Tunnel Boring Machine (TBM) Technology for Underwater Tunnels
Tunnel Boring Machines are mechanised systems used to excavate tunnels through hard rock, soft soil, or mixed ground conditions with minimal surface disruption. For underwater tunnels, specialised TBMs — such as Earth Pressure Balance (EPB) or Slurry Shield machines — are used to manage high water pressure and prevent groundwater ingress. TBMs produce smooth tunnel walls, reducing lining costs and enabling construction in geologically sensitive areas like river beds.
- India has used TBMs in metro rail construction (Delhi, Mumbai, Kolkata) and hydroelectric projects
- The Brahmaputra tunnel will use twin-tube TBM technology — two parallel tubes, each carrying two road lanes, with railway infrastructure provisioned in one tube
- This will be India's first underwater road-and-rail tunnel and the second such multi-modal underwater tunnel globally
- The Engineering, Procurement and Construction (EPC) mode will be used for execution
Connection to this news: The Gohpur-Numaligarh project represents the most ambitious application of TBM technology in India to date, boring 15.79 km through the riverbed of one of the world's largest rivers by discharge volume.
Act East Policy and Northeast Connectivity
India's Act East Policy (upgraded from the Look East Policy in 2014) positions the Northeast as a strategic gateway for economic integration with Southeast Asia and the Indo-Pacific. Major infrastructure initiatives under this framework include the India-Myanmar-Thailand Trilateral Highway, the Kaladan Multi-Modal Transit Transport Project, and extensive railway and road expansion across the eight northeastern states.
- The Northeast is India's sole land corridor to ASEAN nations; the Siliguri Corridor ("Chicken's Neck") — only 22 km wide — is a critical vulnerability
- North East Special Infrastructure Development Scheme (NESIDS) provides central funding for infrastructure gaps
- India-ASEAN trade crossed $130 billion by 2024, with the Northeast positioned as a transit hub
- Recent milestones: Mizoram received its first passenger train in independent India's history; railway connectivity extended to Manipur (Jiribam) and Nagaland
Connection to this news: The Brahmaputra tunnel will integrate NH-15 and NH-715 with key railway sections (Rangia-Murkongselek and Furkating-Mariani lines), connecting 11 economic nodes, 4 railway stations, 2 airports, and 2 inland waterway terminals — directly supporting Act East Policy objectives.
Brahmaputra River — Geographical and Strategic Significance
The Brahmaputra is one of the world's largest rivers, originating as the Yarlung Tsangpo in Tibet near Lake Manasarovar, flowing through the Namcha Barwa gorge into Arunachal Pradesh (where it is called the Dihang/Siang), then through Assam as the Brahmaputra, and into Bangladesh as the Jamuna before merging with the Ganga to form the world's largest delta. It is a braided river in Assam, with Majuli — the world's largest river island — located within it.
- Total length: approximately 2,900 km; drainage area: about 580,000 sq km across Tibet, India, and Bangladesh
- The Brahmaputra divides Assam into north bank and south bank regions, creating a significant connectivity barrier
- It carries enormous sediment loads and is prone to devastating annual floods
- Strategic significance: The river is a natural barrier that any infrastructure must overcome for north-south connectivity in the region
Connection to this news: The Brahmaputra's width, sediment load, and flood dynamics make tunneling beneath it an engineering challenge of global significance. The project addresses the longstanding north-south connectivity divide in Assam.
Key Facts & Data
- Total project cost: Rs 18,662.02 crore (EPC mode)
- Total corridor length: 33.7 km (Gohpur to Numaligarh)
- Tunnel length: 15.79 km (twin-tube, TBM-built)
- Current distance via road: ~240 km; proposed distance: ~34 km
- Employment generation: ~80 lakh man-days
- Connectivity nodes: 11 economic, 3 social, 2 tourist, 8 logistics nodes
- Integrates 4 railway stations, 2 airports, 2 inland waterway terminals
- Highway integration: NH-15 (Gohpur side) and NH-715 (Numaligarh side)
- Railway integration: Rangia-Murkongselek section and Furkating-Mariani loop line