Tunnel construction in India has picked up pace over the years, and has gained notable importance across infrastructure sectors. The rising focus on enhancing all-weather connectivity, especially in hilly terrain, has driven the construction of tunnels in these regions. Rising urbanisation and limited on-ground land availability have pushed connectivity and utility structures underground in the form of tunnels. Apart from this, the need for safe and efficient water distribution networks, irrigation requirements and investments in hydro projects for grid storage, among others, have also driven tunnelling activity over the years.
Tunnelling footprint and recent key developments
Over the past year, tunnel construction in India has made measurable progress. As per projects tracked by India Infrastructure Research, more than 60 tunnels spanning over 100 km were completed in the past one year (June 2024 to May 2025) across various sectors, including metro rail, roads, railways, hydro and water supply. The hydro and roads sectors have led the stream of completed projects, accounting for almost 57 per cent of the total tunnel length completed. Meanwhile, the railways sector leads in terms of the number of tunnels (39 tunnels) completed.
The completion of key tunnelling projects over the past year has significantly expanded the network. The 6.4 km Sonamarg tunnel, or the Z-Morh tunnel, in Jammu & Kashmir was inaugurated in January 2025. The tunnel is expected to enhance road connectivity in the region, boost tourism and serve as a reliable means of commute undisrupted by regional weather adversities such as avalanches, heavy snowfall and landslides. Further, breakthroughs were achieved on various tunnels, including the 4.5 km Silkyara tunnel along NH-134, and tunnels under the Rishikesh-Karnaprayag new rail line project, such as the 14.6 km stretch between Devprayag and Janasu, in April 2025. This is reportedly the longest railway tunnel in the country. Further, tunnelling works on various tunnels under the Bhairabi-Sairang new railway line project also witnessed completion. Commercial operations commenced at the Parbati hydroelectric project (HEP) Stage II, featuring six tunnels with a total length of over 35 km.
The tunnelling sector in India continues to attract significant investment, with expectations of substantial expansion in the country’s tunnel network. Projects tracked by India Infrastructure Research indicate a pipeline of over 1,870 tunnels stretching over 3,010 km under various stages of development, including recently awarded, ongoing, under bidding and planned tunnels. The majority of this tunnel length, spanning over 1,710 km, is under the planned category. Further, recently awarded and ongoing tunnels spanning over 1,170 km are expected to significantly expand the tunnel network in the near term. Over 50 per cent of this tunnel length is concentrated in the railways and hydro sectors, spanning over 330 km and 260 km respectively. Key ongoing projects include the Luhri HEP Stage I, the Nira-Bhima river linking project, and the Mumbai-Ahmedabad high speed rail corridor project.
Trends and advancements in tunnelling techniques
Tunnelling projects across the country have adopted various methods over the years to carry out tunnel excavation. The selection of the tunnelling technique is based on various factors, including length of the tunnel, rock and soil conditions, tunnel diameter and speed requirements. While conventional techniques like the drill and blast method (DBM) and the cut and cover method continue to be used in projects, other methods like the New Austrian Tunnelling Method (NATM) and tunnelling using tunnel boring machines (TBM) are notably gaining traction.
As per projects tracked by India Infrastructure Research, NATM is the most commonly used method of tunnelling in ongoing projects, with over 270 km of tunnel length being constructed using this method alone. In this process, ground conditions are continuously monitored, and surrounding rock support is used for stability, in addition to the use of shotcrete, rock bolts, etc. This method is widely being used across ongoing railway and road tunnels. Moreover, around 75 per cent of the ongoing tunnel length being constructed using NATM is located in the Himalayan region, northern states and north-eastern states. This method is widely preferred in these regions due to its flexibility and suitability for use in varying ground conditions.
The use of TBMs has also gained traction over the years, driven by advantages such as increased efficiency, reduced on-ground disturbances and the ability to work continuously. Various types of TBMs, including double shield TBMs, single shield TBMs and earth pressure balance TBMs are being deployed in various projects. According to projects tracked by India Infrastructure Research, over 240 km of ongoing tunnel length is being constructed using TBMs alone, with a majority of the length (over 165 km) concentrated in the water supply and sewerage, and metro rail sectors. Notably, all ongoing metro projects either use TBMs alone, or TBMs in combination with the cut-and-cover or NATM.
Apart from this, DBM also holds a notable share among ongoing projects, currently being used in over 120 tunnels spanning over 220 km.
Other methods of tunnelling include the Norwegian Method of Tunnelling, micro-tunnelling, the Himalayan tunnelling method and the box-pushing method. The orange line of the Kolkata metro project is using the box-pushing method to carry out tunnelling beneath the airport flyover. It is set to see 14 pre-cast reinforced concrete boxes pushed using hydraulic jacks to form the 135 m tunnel.
Other trends
Integration of technology and focus on safety
The use of new and advanced technologies in tunnelling has witnessed an increased uptake. Its integration into various stages of tunnelling works has significantly improved safety, efficiency and monitoring. Building information modelling, digital twins, artificial intelligence, advanced mapping technologies and drones have been used in the initial surveying processes and during construction activities. Moreover, CCTV cameras, electronic surveillance systems and traffic control systems are being used to monitor movement in operational tunnels.
These technologies play a crucial role in ensuring the safety of operations and the workforce during the construction of tunnels, and in operations post tunnel completion. Safety in tunnels is also ensured with the help of effective tunnel ventilation, firefighting and lighting systems, the use of safer explosives, remote blasting, etc.
Adoption of sustainable initiatives
Sustainability has also emerged as a focus area, in line with the overall net zero goals. Tunnelling projects are focusing on reducing carbon footprint, minimising the negative impacts on the environment and reducing the on-ground vibrations. In this regard, the use of alternative materials with a lower carbon footprint and more efficient machines with lower emissions has opportunities for further deployment. Other measures include the reuse of excavated materials, efficient lighting systems, and use of renewable energy for operations, tunnel ventilation and lighting.
Tunnel projects have also witnessed the adoption of new and advanced materials and equipment for construction. Glass fibre reinforced polymer, geosynthetics, self-drilling rock bolts and advanced waterproofing materials are making headway in the segment. The use of emulsion-based explosives is gaining traction due to their increased efficiency and safety. Moreover, construction processes have also been enhanced with the use of advanced equipment like automated drill jumbos and advanced pumps.
Challenges
While tunnelling techniques have evolved for the better, and the integration of technology is proving to have numerous benefits, the sector is still faced with challenges. Tunnelling in hilly terrain and Himalayan regions are faced with varying ground conditions, complex terrain and adverse weather conditions. These challenges, in addition to situations like landslides, water ingress and cavity formation, further slow and hinder tunnel construction. Further, insufficient ground surveys and investigations during the initial stages could lead to rework and other challenges in later stages. Ambiguities in contracts and documents, diversion of utilities, lack of skilled labour and environmental impacts also continue to pose challenges.
Sector outlook
According to projects tracked by India Infrastructure Research, India currently has a robust pipeline of tunnelling projects comprising over 1,350 tunnels spanning over 1,840 km, which are currently under the planned stage or under bidding. Of this, over 1,020 tunnels with a length of over 790 km are set to come up in the hydro sector alone. Moreover, over 57 per cent of the upcoming tunnelling length is concentrated in five states, namely Maharashtra, Arunachal Pradesh, Jammu & Kashmir, Uttarakhand and Himachal Pradesh. These upcoming projects are set to go into construction in various phases in the coming years, providing numerous opportunities for consultants, contractors, equipment and material providers, technology providers, etc.
Looking ahead, the tunnelling sector is poised to grow backed by the significant investments in infrastructure projects. The integration of technology is further expected to enhance safety, aid in better planning, and streamline tunnel construction processes.
