T
unnel development in India has picked up pace in the past four-five years on account of an increased uptake of projects involving longer tunnel lengths. The growth of this sector has been driven by the robust pipeline of projects in the urban rail, hydropower, railway, roads and highways, and the water supply and sewerage sectors. The scope of tunnel projects is also expanding as a result of growing urbanisation and the rising demand for better infrastructure.
Current market size
As per India Infrastructure Research, over 1,610 tunnels spanning 2,779 km are under various stages of development – completed, under construction and awarded. Of these, 79 per cent of the projects have been completed, 20 per cent are under construction and the remaining 1 per cent have been awarded recently. In terms of length, around 69 per cent of the tunnel length has been completed, 30 per cent is under construction and 1 per cent has been awarded recently.
A sector-wise analysis indicates that the hydropower segment accounts for over 53 per cent of the total tunnel length, followed by the railway and irrigation sectors at 18 per cent and 10 per cent respectively. With regard to completed and ongoing tunnel projects, Himachal Pradesh leads with a tunnel length of 588 km. It is followed by Maharashtra at 345 km and Jammu & Kashmir at 251 km. In addition, the top 10 states account for 76 per cent of the total completed, ongoing and awarded tunnel length.
Some of the recently awarded tunnelling contracts include the 14.5 km Zojila tunnel in Jammu & Kashmir, three-lane twin tunnels with paved shoulders and viaducts spanning 3.44 km on the Mumbai-Goa road in Maharashtra, and the 0.23 km tunnel at Transport Nagar in Uttar Pradesh.
Consolidated market structure
The tunnelling market in India is mostly consolidated, with a few big contractors holding the largest market share. Of the 714 tunnels spanning 1,676 km tracked by India Infrastructure Research, individual contractors or sole contractors of projects account for 51 per cent of the total market share. These are followed by multiple contractor projects with a share of 28 per cent and joint ventures at 2 per cent.
In terms of length, close to 75 per cent of the tunnels (built by individual contractors) were implemented by just 14 contractors, while the remaining were built by 46 contractors. The key contractors in the segment are Hindustan Construction Company, Patel Engineering, Jaiprakash Associates, Ircon, Continental Construction Corporation, ITD Cementation India, Larsen & Toubro, SEW Infrastructure, JSW Energy and Gammon India.
Innovations in construction materials
The quality of construction materials used in tunnelling has evolved over the years. The growing complexity of tunnel construction in the Himalayan and peninsular regions has necessitated the use of new and advanced materials. Tunnel contractors have started deploying various types of new materials to improve the durability and strength of tunnels. These include steel- and fibre-reinforced polymer active anchors, steel passive anchors, expandable friction bolts, self-drilling rock bolts, mechanical single bolts, etc.
TBM technology gaining prominence
Based on the projects tracked, tunnels spanning a length of 1,265.85 km have either been constructed or are under construction using the drill and blast method (DBM) and the New Austrian Tunneling 
Method (NATM) of tunnelling. DBM is the most prominent technique used for tunnelling across all sectors and is deployed mostly in less congested areas and hilly terrains. However, the most advanced method of tunnelling, using a tunnel boring machine (TBM), is slowly gaining market share with increased tunnelling activity in congested urban spaces, primarily for metro and urban water supply projects. According to projects analysed by Indian Infrastructure Research, at least 28 tunnels spanning a total length of over 215 km are either under construction or are planned to be taken up using TBM technology.
In the metro sector alone, tunnels spanning a length of at least 162 km are either under construction or are planned to be taken up using TBM technology. Similarly, in the irrigation and water supply sectors, the technology is being used to construct at least seven tunnels spanning a length of over 50 km.
Evolution of micro-tunnelling
Micro-tunnelling, also known as trenchless or pipe jacking technology, is emerging as a new trend in the country. It is being used to lay water supply pipelines and sewers in congested areas. It is being put to use for laying large diameter gravity sewers in cities where open-cut installation is difficult, for the installation of product pipelines in areas where the soil condition does not allow for horizontal directional drilling, and for long individual crossings across rivers. It is suitable for constructing tunnels with diameters ranging from 600 mm to 3,000 mm.
A remote-controlled steerable boring machine is the main equipment deployed in micro-tunnelling. It is operated from a computer-operated station using drive motor controls. The micro-tunnelling equipment market is dominated by foreign suppliers such as Herrenknecht, Terratec, Robbins, Caterpillar, Akkerman, etc.
Future outlook
Going forward, the outlook for the tunnel development market is promising. Growth will be driven largely by the central government’s focus on infrastructure development. Based on the projects tracked by India Infrastructure Research, the tunnelling segment offers a lucrative pipeline of 1,190 tunnels. These tunnels, spanning a length of over 3,578 km, are under implementation, awarded, under bidding, approved or proposed. In terms of stage of development, 71.53 per cent of the projects are in the planning stage, 23.16 per cent are under construction, 3.9 per cent have been approved, 1 per cent have been awarded and 0.42 per cent are under bidding.
Sector-wise, about 40 per cent of the tunnels in the pipeline are in the hydropower sector, followed by irrigation, water supply and sewerage (25.68 per cent), and railways (12.07 per cent). With regard to tunnelling techniques, DBM will continue to remain the dominant tunnelling technique, particularly in the hydropower and railway sectors, where tunnels are mostly built in the Himalayan region and the Western Ghats. On the other hand, the advanced forms, TBM and NATM, are fast emerging as more cost-effective alternatives for tunnelling projects in congested urban areas.
Overall, with over 76 per cent of projects scheduled for completion by 2021-22, the segment offers vast opportunities to tunnel contractors, material suppliers, and technology and equipment providers over the next three-four years. Based on the pipeline of tunnel projects, the maximum opportunity will be in the northern region, followed by the north-eastern and western regions.
However, there are many factors which can slow down the implementation and execution of tunnelling projects. Geological surprises pose the biggest challenge for contractors. For instance, in the case of the Rohtang tunnel, the challenge was posed by a weak strata that was hampering rock cutting to make way for the 8.8 km horseshoe-shaped tunnel. This, therefore, led to delays in the project despite using mechanised and rapid mining/tunnelling techniques.
Delays in decision-making and land acquisition have also resulted in time and cost overruns in the tunnelling segment. Further, inadequate investigations of ground and soil conditions and the resulting mismatch between the tunnelling method and ground conditions could lead to failure of a tunnelling technique. In addition, the high capital costs of specialised equipment like TBM and the adverse environmental effects of DBM tunnelling also pose hindrances to the development of the segment. These issues need to be addressed on an urgent basis in order to enhance efficiency and ensure timely project execution.