India has become one of the fastest growing markets for tunnel construction globally. With expanding and improving infrastructure, especially in sectors such as urban transportation, water supply and sewerage, hydropower, roads, and railways, there is a growing requirement for tunnel construction. A large number of projects have been commissioned in the recent past and many others are in the pipeline.
A look at some of the recent developments in the sector and the future outlook…
Overview and developments
According to India Infrastructure Research, the country has more than 1,700 tunnels spanning a length of over 3,600 km at various stages of development. These include completed, under-construction and recently awarded projects. In terms of length, the hydropower sector has the highest share of this market with a tunnel length of over 1,500 km, followed by irrigation with over 700 km, and railways with over 650 km. State-wise, Maharashtra accounts for the highest share in the total upcoming length at around 950 km. It is followed by Arunachal Pradesh (more than 290 km) and Uttrakhand (more than 180 km).
With rapid urbanisation, various cities in India are witnessing the development of metro rail systems. Since many metropolitan cities in India are densely populated, underground metro systems are being preferred. These systems are being developed with the cooperation of leading domestic and international players in the tunnelling industry. As per India Infrastructure Research, there are 200 metro tunnelling projects in the country with a length of over 500 km and the construction of over 350 underground stations.
Tunnel construction is achieving many breakthroughs and helping solve problems such as traffic congestion. The sector is increasingly using various modern methods of construction over conventional ones. These tunnels are also driving the demand for tunnelling equipment such as tunnel boring machines (TBMs), hydraulic cutters, wheel loaders, steel ribs, and tunnelling jumbos.
The main tunnel of T-49, the longest tunnel of Indian Railways, between Sumber and Arpinchala station of the Katra-Banihal section of the Udhampur-Srinagar-Baramulla Rail Link (USBRL) project was connected successfully in early 2022. With a tunnel length of 12.76 km, it has surpassed the 11.2 km of tunnel length constructed by USBRL on the Banihal-Qazigund section. Another section of the crucial tunnel T-13 of the same project was completed in August 2022. The completion of the boring work of this important tunnel, connecting Dugga and Basindadhar stations, is a major achievement and connects the Kashmir Valley to the rest of India through the Indian Railways network.
In another development, in June 2022, a new tunnel in Delhi that connects the Ring Road with India Gate, passing through Pragati Maidan, was opened for public use. This was a long-awaited project that had missed several deadlines. Commuters in Delhi had been facing traffic-related challenges for almost a year, and this tunnel is providing major relief. The project has ensured hassle-free movement of vehicles in the city, far beyond the Pragati Maidan area, saving them significant time and cost. The six-lane divided tunnel is also expected to eliminate at least 12,000 tonnes of carbon dioxide emissions in the city.
Another initiative that the government is undertaking is the construction of the first underwater road-cum-rail tunnels across the Brahmaputra river. This will give an impetus to India’s road and rail infrastructure. The project, with an estimated cost of Rs 70 billion, will entail the construction of three tunnels, one for road traffic, one for rail traffic and one for emergency traffic.
Tunnelling activities are also connecting neighbouring countries with India. India and Sri Lanka are working towards building a connecting railway tunnel under the seabed. This tunnel will help in creating new capacities for businesses and the overall economy. It will also help build the BIMSTEC (Bay of Bengal Initiative for Multi-Sectoral Technical and Economic Cooperation) economic community on the lines of the European Union and ASEAN.
Technology and equipment
The drill and blast method (DBM) continues to be the most widely used tunnelling technique in India. According to India Infrastructure Research, tunnels spanning a length of around 1,080 km have been constructed or are being constructed using DBM. The hydropower sector continues to account for the largest share of the DBM market. DBM has also been significantly deployed in the railway sector. This method involves the controlled use of explosives and other methods such as gas pressure blasting pyrotechnics to break rock for excavation. Equipment such as tunnelling jumbos, roadheaders, backhoes and hydraulic cutters are used to dig the tunnel and clear the excavated rock.
Another technology gaining prominence in the country is the New Austrian Tunnelling Method (NATM). This is a preferred method of tunnelling in uncertain geological and hydrogeological conditions. It is now being used in sectors such as railways, metros, roads and highways. This technique was prominently used in the excavation of the Rohtang tunnel in Himachal Pradesh. With the pipeline of metro projects planned for implementation, the use of NATM is expected to increase further in the times ahead.
TBMs are also gaining traction in the roads and highways sector as they are suitable for tunnel construction in urban areas. They are being used as an alternative to the DBM and other conventional methods. Recently, the country’s biggest TBM – Mavala – was deployed in the Mumbai coastal road project. TBMs have also been deployed in Delhi, Mumbai, Pune, Chennai, Bengaluru and Kolkata to build underground metro lines.
Micro-tunnelling is also experiencing increased acceptance in the country. It is emerging as a new trend to lay water supply pipelines and sewers in congested areas. It is especially used for projects that require tunnels under roads with high traffic volumes, railways, rivers, etc. It is used 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. This method is particularly used for constructing tunnels with diameters ranging from 600 mm to 3,000 mm.
The way forward
Tunnelling activity in India has accelerated in recent years due to several growth factors. Increasing government support, adoption of cutting-edge technologies and processes, and initiatives to improve rural connectivity are a few of them. The government’s Gati Shakti Master Plan aims to rapidly accelerate India’s pace of development. It will help in boosting the infrastructure capabilities of the country and give a fillip to the tunnelling sector as well.
Tunnel development in India is largely driven by investments in sectors such as metro rail, railways, roads and highways, hydropower, underground crude oil storage, and water and sewerage. According to India Infrastructure Research, the tunnelling segment offers a lucrative pipeline of over 800 tunnels, spanning a length of around 2,700 km, across various sectors. The total investment required for the construction of these tunnels is expected to be over Rs 5 trillion in the coming years. Investments are expected to come in for many tunnelling projects, including the
six-lane tunnel project on the Pune-Satara highway, being constructed at an estimated cost of Rs 9.26 billion. The project is expected to be completed by March 2023 and will provide commuters with time and cost saving.
Going forward, Indian and foreign joint ventures are expected to continue to show interest in bidding for tunnel construction projects and more players are expected to enter the market. However, there is a need to resolve pressing issues such as delays in land acquisition, contractual issues and lack of skilled manpower to ensure time-bound and effective implementation of projects.