In News:

The Cabinet Committee on Economic Affairs (CCEA) has approved the construction of India’s first underwater twin-tube road-cum-rail tunnel beneath the Brahmaputra River in Assam at a total capital cost of ?18,662 crore. The 33.7 km access-controlled greenfield corridor, including a 15.79 km underwater tunnel, marks a milestone in India’s infrastructure engineering and is expected to significantly enhance connectivity across the Northeast.

Project Overview

What the Project Entails

• Total Length: 33.7 km
• Underwater Twin-Tube Tunnel: 15.79 km beneath the Brahmaputra
• Corridor: Gohpur (NH-15) to Numaligarh (NH-715)
• Development Mode: Engineering, Procurement and Construction (EPC)
• Total Capital Cost: ?18,662 crore
  • Civil Cost: ?11,982.36 crore
  • Land Acquisition: ?716.65 crore

The project integrates road and rail infrastructure, making it India’s first underwater road-cum-rail tunnel and only the second such structure globally.

Key Engineering Features

• Twin-Tube Design: Two parallel tubes ensure traffic segregation, safety redundancy, and efficient emergency evacuation systems. One tube will also incorporate railway infrastructure.
• Access-Controlled Greenfield Corridor: A four-lane highway designed for high-speed, uninterrupted travel.
• Multi-Modal Integration:
  • Connects NH-15 and NH-715
  • Integrates with Rangia–Mukongselek and Furkating–Mariani railway sections under Northeast Frontier Railway
  • Links 4 major railway stations, 2 airports (Holongi and Tezpur), and 2 inland waterway terminals
• Traffic and Logistics Impact:
  • Reduces distance from 240 km to 34 km
  • Cuts travel time from 6 hours to 20 minutes
  • Estimated AADT (FY-25): 4,680 PCUs

About the Brahmaputra River

The Brahmaputra is one of Asia’s largest rivers, originating from the Chemayungdung Glacier near Lake Mapam in Tibet (~5,300 m). Known as Yarlung Tsangpo in Tibet, Siang/Dihang in Arunachal Pradesh, and Jamuna in Bangladesh, it flows through China, India, and Bangladesh.

• Length: ~2,900 km
• Among the world’s highest average river discharges
• Forms the world’s largest delta with the Ganga
• Characterised by highly braided channels in Assam

Constructing an underwater tunnel beneath such a dynamic and sediment-laden river demonstrates advanced tunnelling and geotechnical capability.

Regional and Strategic Significance

1. Boost to Northeast Connectivity: Though located in Assam, the project benefits Arunachal Pradesh, Nagaland, and the wider Northeast region, improving passenger and freight mobility.

2. Economic Multiplier Effects

• Connects 11 economic nodes, including industrial areas and logistics hubs.
• Facilitates faster freight movement and reduces logistics costs.
• Expected to generate 80 lakh person-days of employment (direct and indirect).

3. Tourism and Social Connectivity

• Enhances access to Kaziranga National Park and Deopahar Archaeological Site.
• Connects aspirational districts like Udalguri and Darrang and tribal district Dima Hasao.

4. Strategic and Border Importance: Improves connectivity to Arunachal Pradesh, strengthening infrastructure in border areas and enhancing national security preparedness.