Tunnel infrastructure is gradually maturing with strategic expansion and investments across multiple domains such as urban mass transit, roadways and highway corridors, and water resource management like irrigation practices and hydropower projects. This growth reflects both functional needs and spatial constraints, as underground tunnelling solutions increasingly address challenges related to difficult terrain, congestion and limited land availability. A sectoral analysis based on completed projects during June 2024 to
May 2025 tracked by India Infrastructure research reveals that hydropower and road tunnels comprised the largest shares of the completed length with 31 per cent and 24 per cent respectively, while metro and railway tunnels follow, contributing 18 per cent each, and lastly water tunnels with 9 per cent. Over the past year (from June 2024 to May 2025), more than 100 km of over 60 tunnels were completed in around 26 projects across sectors. This demonstrates the diversity of applications and the growing scale of implementation.
Hydropower tunnels
The growing demand for efficient and long-duration grid storage solutions has accelerated investments in hydropower projects. Tunnel infrastructure forms an important part of such projects by facilitating water conveyance and pressure management. A steady pace of project completion in the past one year has been observed in the sector. Around 32 km of hydro tunnel length across seven projects were completed between June 2024 and May 2025. A key milestone was the operationalisation of NHPC’s project in Himachal Pradesh in April 2025, which includes an around 32 km of headrace tunnel comprising both a drill-and-blast method (DBM) section and a tunnel boring machine (TBM)-driven segment. This reflects the increasing integration of hybrid excavation methods to optimise performance across varied geological conditions.
In terms of new developments, around 25 tunnel contracts for over 15 km in length were awarded in the same period. Leading contractors such as PES Engineers, Patel Engineering and Rail Vikas Nigam Limited (RVNL) were among the recipients. The 240 MW Heo Hydro Electric Project, awarded to Patel Engineering in May 2025, comprises five tunnels across a total length of 3.65 km. Such projects reinforce the role of tunnel infrastructure in enhancing renewable energy capacity.
Road tunnels
Road tunnel infrastructure is being expanded in India as a solution to mitigate urban congestion by enabling direct and uninterrupted connectivity between high-traffic nodes. These tunnel projects have proven critical, complementing road networks in metropolitan cities and, in turn, significantly reducing travel time and enhancing vehicular efficiency. The road sector witnessed the completion of a few projects during June 2024 to May 2025. More than 25 km of 16 road tunnels were completed across nine road tunnel projects. A key milestone was achieved on April 16, 2025, with the breakthrough of the 4.5 km Dharasu-Yamunotri section of the Silkyara tunnel in Uttarakhand, executed using the New Austrian Tunnelling Method (NATM) at a cost of Rs 8.5 billion. Similarly, on March 4, 2025, the National Highways Authority of India achieved a major milestone by completing the Mukundra Tiger Reserve twin tunnels of 4.89 km in length under Package 15 of the Delhi-Vadodara eight-lane expressway. It is a segment of the Delhi-Mumbai expressway under the Bharatmala Pariyojana.
Furthermore, several large-value tunnel contracts were awarded during this period; this signals continued public investment in tunnel infrastructure. For instance, in October 2024, PNC Infratech Limited secured Package PRR E2 of the Indori-Chimbali tunnel project (east stretch), covering a 13.8 km segment in Maharashtra.
Metro tunnels
The tunnel infrastructure for metro projects is developing at a fast pace in the country, with tunnels being a critical enabler in urban rail connectivity. Over 18 km of metro tunnels across six projects have been completed between June 2024 and May 2025. Significant completions include the 7.2 km twin tunnels under the Kolkata East-West Metro Project and the 4.6 km segment of the Bengaluru Metro phase II Project. The recent award of the Indore metro’s 8.6 km IN-05R tunnelling package to the joint venture of HCC Limited and Tata Projects further indicates sustained project momentum. The package involves integrated underground station development and access infrastructure along with tunnelling works.
The technical landscape of Indian metro tunnelling is also adapting in response to site-specific constraints and subsurface heterogeneity. TBM remains the primary tunnelling technique, supported by the NATM and cut-and-cover methods where conditions demand flexibility. This is evident in the Chennai Metro Rail Project Phase II, where TBM S-1326A achieved its first breakthrough on Corridor 3 (Madhavaram Milk Colony to SIPCOT) at the Adyar Junction station in February 2025. Similarly, on the same corridor, the TBM technique was deployed at the Perambur station and achieved a breakthrough in May 2025.
Railways
Tunnel construction activity is gathering momentum in the sector, helping the railways traverse mountainous and rugged terrain, especially in the north-eastern region. Out of 39 tunnels, around 19 km of tunnel length was completed between June 2024 and May 2025. Among these, several sections of the Bhairabi-Sairang New Railway Line Project in Mizoram were completed in May 2025. The Bhairabi-Mualkhang section was longest with around 6 km length. Similarly, the Sukhovi-Molvom section of the Dhansiri-Sukhobi-Zubza New Line Railway Project in Nagaland and Assam with around 4 km in length was completed in March 2025. Another major milestone was achieved with the award of the Budni-Indore New Railway Line Project in Madhya Pradesh in March 2025. The two tunnels in its package will cover around 10 km in length and their construction work has been awarded to the joint venture of IRCON International Limited and SSNR Projects Private Limited.
Water supply and irrigation tunnels
The growing demand for irrigation in agriculture and the parallel need for reliable water supply systems have led to the development of extensive pipeline and tunnel infrastructure for water conveyance. Tunnel construction in these sectors typically employs a combination of techniques based on subsurface conditions. Vertical shafts are constructed using well sinking or secant piling in softer soils, while DBM is preferred in hard rock environments, especially for TBM assembly chambers. Main tunnel excavation is often carried out using hard rock gripper TBMs, with muck removal facilitated through wagons or conveyor systems.
Despite these advancements, the pace of project execution remains modest. Between June 2024 and May 2025, approximately 41 km of tunnelling works were awarded across six projects in both sectors. The major players involved include Apco Infratech, Afcons Infrastructure, Prasad and Company Project Works Limited, Sarala Project Works Private Limited, and Welspun Enterprises. A notable contract that was awarded in the water sector was the 8.5 km Dharavi wastewater treatment facility (WWTF)-Ghatkopar tunnel project in Maharashtra, awarded to Welspun Enterprises in October 2024. Additionally, significant progress was observed in irrigation tunnels, with the contract for the Khadakwasla-Phursungi Underground Tunnel Irrigation Project awarded to Megha Engineering and Infrastructure Limited in October 2024. The tunnel will span 23.45 km from the Khadakwasla dam to the New Mutha Right Bank Canal (RBC), and will involve works on a cofferdam, six shafts, intake structure, cuts and cover, open cut, a diversion road and an approach road.
The way ahead
Going forward, given the convergence of urban infrastructure growth and modernisation and clean energy requirements, tunnelling works under all sectors are expected to receive a huge push. According to on India Infrastructure Research, over 1,350 tunnels more than 1,800 km in length are currently at the planning or bidding stage in project packages. Moreover, work on over 500 tunnels in project packages is under way. These tunnels are expected to add a length of over 1,100 km to the tunnel network in the next five to seven years. In the time to come, technological advancements will take centre stage. Ranging from hybrid TBM applications to real-time geotechnical monitoring, these upgradations are set to enhance execution efficiency, safety, and cost-effectiveness. At the same time, the sector must address key challenges, including complex geological conditions, land acquisition delays and limited technical workforce capacity. A stronger policy thrust on risk-sharing frameworks, skill development and innovation in construction techniques will be critical to unlocking the full potential of underground infrastructure.
