What’s Driving Growth of India's Tunnelling Industry

Tunnel construction in the country has picked up pace in the past four-five years on account of an increased number of projects involving longer tunnel lengths, and in some of the world’s most difficult terrain conditions. The scope of tunnel projects is also expanding due to the growing urbanisation and rising demand for better infrastructure.

While the railway sector was the first to undertake tunnel development, the maximum number of tunnels have been developed in the hydropower sector. Tunnels for supply of water got boost with the launch of programs such as the Jawaharlal Nehru National Urban Renewal Mission, the Pradhan Mantri Krishi Sinchayee Yojana, and the Interlinking of Rivers program for exploitation of water resources. The roads and highways sector witnessed a rise in tunnel construction especially in the hilly regions. Metro rail tunnelling is a recent phenomenon, spurred by dense cities requiring efficient public mass transport systems.

As per the current market size of tunnelling projects tracked by Tunnelling Association of India (TAI), India has more than 2,500 km of completed tunnel length. A sector-wise analysis indicates that the hydropower sector has the highest share of completed tunnels of over 1,200 km, followed by irrigation (more than 470 km), railways (more than 270 km), metro tunnels (more than 240 km), water and sewerage (more than 230 km) and roads (more than 60 km).

The size and growth – Sector wise of tunnels is as given below:
A pipeline of 1726 tunnels spanning 3600 km are currently in various stages of development - either completed, under implementation, awarded, under bidding, announced, approved, planned/proposed or stalled. Of these, 75% have been completed; 22% are under construction; and the remaining 3% have been recently awarded. In terms of Length of Tunnels in India (km), the analysed tunnel length, 62% has been completed, construction work is going on 36% tunnel length, and the remaining 2% has been recently awarded.

As regards upcoming tunnels (under planning, under bidding and ongoing categories), Jammu & Kashmir has the largest pipeline with around 200 tunnels, followed by Maharashtra (around 140 tunnels), Himachal Pradesh (more than 100 tunnels), Andhra Pradesh (around 90 tunnels) and Arunachal Pradesh (around 80 tunnels). In terms of upcoming length, Maharashtra has the maximum share with over 1,100 km, followed by Jammu & Kashmir with over 460 km, and Uttarakhand with more than 280 km.

Advancements in Tunnelling Techniques and Equipment

Advancements in tunnelling techniques have catalyzed faster and more efficient construction practices in underground space engineering. This progress has instigated a surge in demand for high-tech equipment, driven by the complexities of geological conditions and the imperative for accelerated project timelines. Typically, a significant portion, approximately 25-30%, of tunnel construction expenditure is allocated to equipment and machinery procurement. Over the forthcoming 3-4 years, an estimated Rs. 1170 billion will be invested in acquiring equipment and machinery for upcoming tunnel projects, contingent on factors such as the chosen tunneling method, geological intricacies, and technological sophistication.


The Indian tunnelling industry is progressively embracing modern technology, opening avenues for the adoption of international standards in tunnel design and construction. Particularly in regions characterized by formidable geological challenges, such as the Himalayan region and the Western Ghats, there is a burgeoning demand for high-tech tunneling equipment. Comprehensive soil and rock investigations, coupled with ground behavior analysis during tunnelling, underscore the importance of mechanized methods like Tunnel Boring Machines (TBMs) and New Austrian Tunnelling Method (NATM) in overcoming these challenges, supplanting conventional drill and blast techniques.

NATM, renowned for its adaptability in uncertain geological and hydrogeological contexts, has gained significant traction across various sectors including railways, metros, roads, and highways. Similarly, TBMs are increasingly favored in urban settings for their efficacy in tunnel construction, with over 380 km of upcoming tunnels employing TBMs alongside complementary techniques.


Micro-tunnelling, an advanced technique adept at laying deep water supply and sewer lines in congested areas where open cut tunnelling is impractical, is also gaining acceptance. Notably, conventional methods like the drill and blast method (DBM) retain their prominence, accounting for more than 200 km of ongoing tunnel projects, often in conjunction with other methodologies. In hydro tunnel works, DBM is anticipated to retain its preference in over 38% of projects.

Looking ahead, TBMs, Earth Pressure Balance Machines (EPBMs), and Slurry machines are poised to dominate metro, irrigation, and water supply tunneling projects, while simpler equipment like drilling jumbos and excavators will witness increased demand, especially in hydro projects. The adoption of mechanized methods like TBMs and NATM in congested urban environments will propel the demand for specialized equipment such as cutter heads, shield machines, and pressure transducers, complemented by advanced navigation and drilling systems for enhanced precision and monitoring.


Contractors are at the vanguard of exploring modern tunnel construction techniques, leveraging features like video surveillance, integrated tunnel control systems, and innovative materials such as fiber bolts and geosynthetics. Noteworthy innovations include the development of smart tunnels exemplified by the Zojila tunnel project in India, which integrates advanced safety features like fully transverse ventilation systems and CCTV monitoring.

Additionally, contractors are pioneering new methodologies such as the P5 system, sequential excavation systems, and ground freezing to address geological challenges, employing innovative materials to fortify tunnel durability and strength. Enhanced geological and geotechnical investigations are facilitated through technologies like aerial and photogrammetry-based surveys and GPS-based mapping systems, further augmenting the efficacy of tunnel construction endeavors.

New Trends & Materials

The tunnelling segment has seen the emergence of new trends such as the use of steel fibres in shotcrete; self-drilling anchor bolts; adoption of methods such as PU grout, pipe roofing and pre-grouting techniques; and use of other advanced materials; among others. In the past few years, the Indian tunnelling industry has increased the deployment of modern technology for tunnel construction. Advanced technologies such as TBM and NATM are extensively being used for tunnelling activity in congested urban areas.


With regard to the equipment market, increasing investments in tunnel construction have resulted in high growth in the tunnel equipment market as well. Going forward, as the pressure on land increases (with land being required for other productive economic and social uses) there will be a greater need to construct underground structures in the metro, water and sewerage, and road sectors.

New and innovative materials are being used to improve the durability and strength of tunnels. The application of unique and cutting-edge materials has become essential due to the increasing complexity of tunnel construction, especially in the Himalayan and peninsular regions. Tunnel contractors have begun utilising a variety of innovative materials, such as mechanical single bolts, expanding friction bolts, self-drilling rock bolts, steel-and fibre-reinforced polymer active anchors, steel passive anchors, etc, for increased construction efficiency.

Some Landmark Tunnel Projects

Hydro tunnels account for the largest share, followed by railways, irrigation, metro rail, water supply, sewerage, roads and highways. One of the vital projects of this sector is the Upper Siang Hydropower project in Arunachal Pradesh which involves construction of 30 tunnels in a horseshoe-shape; it is the most prominent tunnel design in hydropower projects across India. Other key tunnel projects in the hydro sector include Dibang, Sawalkote, and Subhanshri Middle hydroelectric projects - all of which will be constructed in the horseshoe shape.

Currently, many landmark and challenging highway and rail tunnel projects in hilly areas are under various stages of execution. These include the 125 km Rishikesh Karanprayag railway project where track route length of 17 Nos in tunnel of 104 km where the longest tunnel T 8 is 14.58 km; NCRTC RRTS project having 6.7 km out of the 12.36 km underground stretch of Delhi-Meerut corridor is in Delhi, the construction of the underground section of approx. 5 km of Twin Tunnel (10 km total tunnel length); USBRL railway project of the 272 km, having 161 km, (Udhampur-Katra- 25 km, Quazigund- Baramulla - 118 km, Banihal-Quazigund -18 km) in tunnels. Work on the intervening stretch of Katra-Banihal section (111 km) is in progress. This section primarily involves tunnelling, with 97.4 km (87% of the section's total length) being covered by tunnels. The longest tunnel, T-49, stretches over 12.77 km, making it the longest railway tunnel in the country. There are a total of 27 Main tunnels, covering a length of 97.42 km, and 8 Escape tunnels, spanning 66.4 km, resulting in a cumulative length of 163.82 km; Zojila Road Tunnel in J&K to Leh of 14.2 km single tube with two traffic lanes; Pir-Ki-Gali Tunnel in J&K with tunnel length of 8.508 km; Vailoo Tunnel in J&K of 8.5 km; Daranga Tunnel in J&K of 4.5 km length; Kiratpur-Neharchowk: 5.0 km; Pandoh: 10 km; and Shimla By-Pass: 6.0 km; 11.55-km tunnel on the Jiribam Tupul-Imphal rail line, and the 4.5-km Char Dham tunnel. Other landmark and challenging tunnel construction projects under execution include the Kaleshwaram Lift Irrigation Scheme (total length of 203 km), the 33.5 km Mumbai Metro Line 3, and the 7 km undersea tunnel of the Mumbai-Ahmedabad high-speed rail project.

Risks & Challenges During Tunnelling

The tunnelling sector in India continues to face several issues and challenges. Key amongst them are inappropriately designed contract documents and inadequate contracting practices. The contracts are drafted on age-old norms and leave substantial room for ambiguity in the roles of the implementing agency and contractors.

Another challenge faced by tunnelling contractors is the shortage of skilled manpower for handling sophisticated tunnelling equipment. Due to inadequate training, many tunnel construction personnel lack the machinery expertise and are unable to address the obstacles that occur.

Other challenges include lack of safety in tunnel construction and maintenance, inadequate investigations, risk management, undefined methodologies for working out rates for extra items, and deviations in the design or construction requirements. These challenges eventually lead to considerable cost and time overruns. The tunnelling segment continues to struggle with the issues that include:

• Geological complexities: Geological surprises are one of the biggest challenges. Complexities in the Himalayan region such as difficult terrains, thrust zones, shear zones, lack of mapping of in-situ stresses, high rock cover, ingress of water or gases, geothermal gradient, high level of seismicity etc. affect tunnelling activity.
• Inadequate investigations: Despite the availability of expert agencies in the country, there is usually an insufficient budget allocated for thorough investigations and less time given for site surveys and geological-geotechnical investigation, which affect tunnelling activities. Inadequate investigations lead to high risk in contractual costs.
• Mismanaged contracts: Ambiguity in the design of construction contracts affects the progress of tunnel construction. Any deficiency in the existing contract documents, and lack of risk sharing mechanisms lead to botched post contract practices.
• Risk management: Higher safety risks and inadequate safety measures are other challenges in tunnel construction.
• Health and safety risk issues: Inadequate ventilation during construction of long tunnels and insufficient safety measures (in case of sudden ingress of water), affect construction progress.
• Other issues: Environmental impact, need for skilled manpower for manning and maintaining the sophisticated equipment, equipment related issues, opposition from local population during land acquisition are some other issues.

These risks and challenges may increase or decrease as per the geology of the project, its location, the developer, contractor, and the contracting terms and conditions. There can be considerable time and cost overruns if the necessary attention is not paid during the pre-construction phase, especially during geological investigations, and in defining the risks under the terms and conditions in the contract. Any neglect at this stage can have grave consequences, including abandonment or stalling of the project.

Tunnel risks and challenges are often associated with unpredictable soil and groundwater conditions, difficult environments, rocks of various types, which may traverse zones of various complexities. Risk events are often interrelated: there can be untoward incidents such as fire, landslide, and flooding, which will lead to delays, environmental impact, and cost overruns, and there is a possible risk of damage to the surrounding properties and persons, especially in dense cities and towns.

To mitigate risks, tunnel projects should be conceptualized and planned systematically to ensure smooth implementation; adequate investigations carried out, proper selection of tunnelling equipment made, appropriate contracting practices documented, statutory clearances taken, competent construction subcontractors deployed, and social issues duly considered. Every tunnelling project, from its conception to commissioning, is influenced by the geology of the area, so, reliability of the predicted geology is important. Some projects are primarily schedule driven, while others are cost or quality driven. Whether a specific risk event is perceived fundamentally as a cost risk, or a schedule risk, is governed by the project-specific context.

All these challenges may result in increased cost and extended completion period. So, one must carefully consider the likelihood of a risk occurrence and its impact in the context of a specific set of project conditions and circumstances. Herein lies the challenge between failure and success.

Tunnelling Growth Opportunities

India is one of the fastest growing markets for tunnel construction, with the tunnelling industry witnessing high growth and ready to adopt advanced technologies. Over the past few years, the size of tunnelling projects has witnessed a substantial increase. Almost all the upcoming tunnel projects are of longer lengths, larger diameters, and even higher contract values. Rising investments in tunnel construction have resulted in high growth in the tunnel equipment market as well. Going forward, the overall outlook for tunnel development in the country remains promising as the pressure on land increases for productive economic and social uses and there will be greater need to construct underground structures in the metro, water and sewerage, and road sectors.

Many new tunnel projects are in the pipeline; this holds immense promise for contractors, consultants, technology and equipment providers, material suppliers etc. over the long term. The schemes and programmes of the government such as the Gati Shakti Master Plan are expected to boost the infrastructure capabilities in the country and thereby provide a fillip to the tunnelling sector. Apart from these, the Bharatmala, Chardham connectivity, AMRUT, and the Smart Cities Mission will also offer ample opportunities to all the agencies involved with the development of tunnel and underground space in the country.

Future tunnel construction projects are anticipated to draw interest from Indian and foreign joint ventures, either for risk assessment, design or construction technology. The industry will witness reduced risks in project construction and timely completion besides ability to address pressing issues including the lack of skilled manpower, contract disputes and delays in land acquisition.

Tunnelling projects in India are expected to increasingly deploy smart and digital solutions in order to enhance efficiency in operations and safety, and enable cost savings. However, there is a need to resolve pressing issues such as delays in land acquisition, contractual issues, lack of skilled manpower, etc., to ensure time bound and effective implementation of projects.