- India
- Jan 15
India’s evolving tunnel technology and landmark projects
• Built using modern engineering and innovative planning, tunnels play a vital role in economic growth, national security, and regional development.
• From strategic Himalayan tunnels to urban metro networks, these projects are transforming how India moves people, goods, and resources.
• By cutting through mountains and terrain that once limited connectivity, tunnels have enabled year-round transportation.
• They have also improved access to remote regions and strengthened links between communities.
• India’s tunnelling boom is being propelled by national highway expansion, alongside strategic border infrastructure, metro rail growth, bullet-train corridors, and all-weather connectivity initiatives in remote regions.
Evolving tunnel technology
• Over the past decade, India’s tunnelling capability has transformed. It has progressed from traditional drill-and-blast methods to sophisticated technologies.
• Modern projects now rely on advanced geological mapping and real-time monitoring systems, allowing the engineers to construct longer and deeper tunnels even in harsh conditions.
• Contemporary Indian tunnels are designed as high-tech, safety-integrated corridors equipped with engineered ventilation systems, emergency escape routes, fire-suppression units, LED lighting, CCTV surveillance, and centralised tunnel control rooms.
• This modernisation has significantly improved both operational reliability and disaster readiness.
Key technologies driving India’s tunnel revolution:
i) Tunnel Boring Machines (TBMs): Used extensively in metro networks and long rail/road tunnels, TBMs provide high precision, reduced vibration, and enhanced safety in densely populated and geologically complex regions.
ii) New Austrian Tunnelling Method (NATM): Widely adopted in the Himalayas, NATM allows engineers to adapt excavation support in real time, making it ideal for variable and fragile rock formations.
iii) Integrated Tunnel Control Systems (ITCS): Critical for modern road tunnels, ITCS combines ventilation control, fire detection, communication networks, CCTV, and emergency management into a centralised digital platform, ensuring 24/7 safety.
Some landmark tunnel projects
1) Atal Tunnel
Tucked beneath the snow-laden peaks of the Pir Panjal ranges, the Atal Tunnel stretches 9.02 km, providing a high-altitude passage that bypasses Rohtang Pass. Its completion has transformed connectivity, enabling seamless, year-round travel between Manali and the remote valleys of Lahaul‑Spiti. The tunnel’s strategic significance also lies in ensuring safe, reliable access for civilians and defence movement alike under challenging mountain conditions. It is officially recognised as the World’s Longest Highway Tunnel above 10,000 feet in 2022 by the World Book of Records UK. The tunnel has cut the Manali–Sarchu distance by 46 km and reduced travel time by four to five hours.
2) Sonamarg Tunnel (Z-Morh)
The Sonamarg Tunnel, a 12-km engineering feat carved through mountains at an altitude of over 8,650 feet above sea level, is in Jammu & Kashmir. It is built at a cost of Rs 2,700 crore. It includes a 6.4-km main tunnel, an egress tunnel, and modern approach roads creating an all-weather lifeline between Srinagar and the golden meadows of Sonamarg, and further towards Ladakh. No longer will avalanches, landslides, or heavy snowfall cut the region off. The tunnel keeps the route open improving access to major hospitals and ensuring the availability of essential supplies. It is designed to handle about 1,000 vehicles per hour. Once paired with the upcoming Zojila Tunnel (2028), the journey will shrink from 49 km to 43 km, with speeds rising from 30 km/hr to 70 km/hr, boosting defense logistics, winter tourism, adventure sports, and the livelihoods of the people who call these mountains home.
3) Sela Tunnel
The Sela Tunnel was built by the Border Roads Organisation (BRO) at 13,000 feet on the Tezpur-Tawang route in Arunachal Pradesh. The tunnel is constructed at a cost of Rs 825 crore. It ensures all-weather connectivity and holds immense strategic value for the Armed Forces while boosting socio-economic growth in the border region.
4) Banihal-Qazigund Road Tunnel
The Banihal–Qazigund Road Tunnel, constructed at a cost of over Rs 3,100 crore, is an 8.45-km-long twin-tube tunnel designed to significantly improve connectivity between Jammu and Kashmir. The tunnel has reduced the road distance between Banihal and Qazigund by 16 km and has cut travel time by approximately one and a half hours. Built with two separate tubes, one for each direction of traffic, the tunnel is interconnected by cross passages at every 500 metres to facilitate maintenance and emergency evacuation.
5) Dr Syama Prasad Mookerjee Tunnel
Dr Syama Prasad Mookerjee Tunnel, formerly known as the Chenani–Nashri Tunnel in Jammu & Kashmir, is a 9-km-long, twin-tube, all-weather road tunnel connecting Udhampur and Ramban. Built at an elevation of about 1,200 metres in difficult Himalayan terrain, it has reduced travel time between Jammu and Srinagar by nearly two hours while bypassing 41 km of road length.
6) Tunnel T50 under USBRL Project
Tunnel T50, a 12.77-km engineering feat connecting Khari and Sumber in Jammu & Kashmir, stands as one of India’s longest transportation tunnel constructed under the Udhampur-Srinagar-Baramulla Rail Link (USBRL) project, forming a crucial rail lifeline between the Kashmir Valley and the rest of the country. Constructed using the New Austrian Tunnelling Method, it cuts through challenging geology ranging from quartzite and gneiss to phyllite, with engineers overcoming high-water ingress, landslides, shear zones, and jointed volcanic rock. The tunnel features a main tube paired with a parallel escape tunnel, linked every 375 metres for safety. Enhanced with CCTV cameras placed every 50 metres and monitored from a central control room, T50 is designed for secure, seamless rail operations.
7) Kolkata's Underwater Metro Tunnel
In 2024, India marked a historic breakthrough with the launch of its first underwater metro tunnel in Kolkata, linking Esplanade and Howrah Maidan beneath the Hooghly River. The 4.8-km Esplanade-Howrah Maidan stretch, which is a part of the East-West Corridor, has been built at a cost of Rs 4,960 crore.
Forthcoming tunnel projects
1) Zojila Tunnel
The Zojila Tunnel is emerging as a monumental achievement in India’s infrastructure landscape, cutting through some of the most formidable Himalayan rock formations to establish a dependable, all-weather link between Ladakh and the rest of the country. Nearly 12 kilometers of the project is already completed. Once completed, this ambitious undertaking will become India’s longest road tunnel and Asia’s longest bi-directional tunnel, reinforcing its national significance. Rising at an altitude of 11,578 feet and unfolding across over 30 kilometers, the project is on track for a 2028 completion. As a critical component of the Srinagar Kargil-Leh National Highway, it promises to enhance both civilian and military mobility across the region.
2) Mumbai-Ahmedabad High-Speed Rail Tunnel
India’s Mumbai-Ahmedabad High-Speed Rail corridor has marked a futuristic leap with the breakthrough on its 4.8-km undersea tunnel section. It is a defining feature of the nation’s first bullet-train route. Excavated simultaneously from the Ghansoli and Shilphata ends, the tunnel posed extraordinary challenges. The teams advanced through difficult underwater terrain before meeting with precision, an achievement hailed as a landmark in India’s engineering history. Designed using single-tube technology capable of housing two high-speed trains, this tunnel stands at the forefront of cutting-edge rail construction and reflects the innovation driving India’s next-generation transport infrastructure.
3) Rishikesh-Karnaprayag New Rail Line Project Tunnels
The Rishikesh-Karnaprayag rail line in Uttarakhand is a landmark tunnelling project in the Indian Himalayas. Spanning about 125 km, the alignment passes through some of the most geologically complex and environmentally sensitive Himalayan terrain. This has resulted in the project being predominantly tunnel-based. It comprises 16 main line tunnels with a cumulative length of approximately 105 km and 12 parallel escape tunnels totaling about 98 km. Overall, 199 km of tunnelling has been completed against a total scope of 213 km.