Tunnelling: The big bore

Compared with other countries like China, India has just taken baby steps. But as cities burst at the seams, more hydro projects are sanctioned in the north east and challenging rail projects are underway, new technology emerges at the hands of international players-these could be from the highly experienced China, writes A Shivkamal.

In the 1970s, India opened a new sector in infrastructure development-tunnelling-for hydro power projects, irrigation and urban water supply and sewage management, as the consecutive Five Year Plans stressed on agricultural development backed by irrigation. Back then, tunnelling and consultancy work related to it was an exclusive domain of the public sector, particularly the Central government agencies. Forty years later, the scenario has changed completely with tunnelling projects moving beyond hydro power and irrigation to railways, urban transportation systems and road connectivity in the mountainous region. Today, tunnelling is no more an exclusive domain of the government sector, with MNC firms, both in tunnel construction and consultancy, actively participating in government-sponsored and private sector projects in the country.

At present, the tunnelling projects in India is divided into two categories-infrastructure development and transportation sector. In the infrastructure development sector, power projects, irrigation projects and water supply and sewage management are categorised. In the transportation sector, railway network expansion, highway road development and widening, urban transportation solutions, such as, metro, monorail, bus rapid transit system, and city road infrastructure development works are undertaken.

"While the early economic development of the country saw massive tunnelling projects in the infrastructure development category, these days, transportation sector is driving the business for tunnelling projects in the country. Over the next two decades, we can expect a healthy CAGR in tunnelling projects with every city now opting for metro projects, widening national highways and expanding railway network in the Himalayas," says Dr SA Ramachandran, Executive Director, Sped Tunnel Consultancy Works.

These developments, Ramachandran says, are attracting many international players such as Samsung (South Korea), Shimizu (Japan), DYWIDAG International GmbH (Germany), Leighton Welspun (Australia), specialised in tunnel designing, equipment hiring, tunnelling and maintenance works. For the first five decades after the country’s independence, foreign players with expertise were not allowed to participate in tunnelling projects because of the nature of the work involved.

Opening up to private

"Power projects, tunnel construction in the Himalayas and irrigation projects were all considered as strategic and sensitive. Back then, the mindset against employing international agencies was purely driven from security perspective because of the number of wars we fought against them. However, now, the scenario has completely changed. With private sector also getting into the business, it was only a matter of time before the government opened up the sector for private players," observes AH Mahadev, Retired Chief Engineer from the Karnataka Power Corporation (KPCL).

The KPCL undertook tunnelling projects for Kali Hydro Power Station, Linganmakki Power Station and Almatti Dam House. However, it was not at liberty to utilise the expertise of international players. In the absence of the latest tunnelling technology and access to modern tunnelling equipment, project management became a major issue, leading to inordinate delays in commissioning the projects.

Experts are of the view that the business proposition for tunnelling in the infrastructure development is poor. "Our dependence on hydro power was very high during the 1970s," explains Dr TH Hanumanthaiah, Member, Geological Society of India, and retired professor of Geological Sciences. "Major irrigation projects were also commissioned during the same period. India is done with most of those projects in the last five decades. Moreover, with a growing environmental concern, damming rivers in the Himalayas and forested regions of the Western Ghats are no longer feasible or environmentally viable. This has prompted international agencies to examine business opportunities in the transportation sector."

Scientific studies have indicated that we have more than exploited the Himalayas and the Western Ghats for power and irrigation projects, so the days of big dams are more or less over, and there is little prospect for tunnelling projects in these two sectors. With the well-documented ecological damage because of damming Himalayan rivers and the west-flowing rivers in south India, the governments will find it difficult to approve such projects any more, and their gestation period is higher. Experts believe that under such circumstances, it does not make for a good business proposition for international firms to participate in such ventures.

However, the tunnelling business from power and irrigation projects has not completely eroded. At present, tunnelling projects for irrigation and hydropower station are in progress in Andhra Pradesh, Assam and Madhya Pradesh. In Andhra Pradesh, the Veligonda project is said to be a tunnel engineering feat. With a length of almost 19 km, the Veligonda tunnel passes under the Rajiv Gandhi Nature Reserve, a tiger habitat. The project aims to tap into the Srisailam dam with an underground tunnel, so that water can be diverted to drought-ridden areas when the dam reaches its full capacity. A huge Herrenknecht hard rock double shield tunnel boring machine (TBM) is currently at work. The 2,800 kW TBM is boring the 19 km-long tunnel at depths of as much as 550 m. On-site support for the project is being provided by Herrenknecht subsidiary, Underground Technology Service (UTS).

Mega projects

There is tremendous scope for tunnelling projects in urban infrastructure development with several cities being funded under the Jawaharlal Nehru National Urban Renewal Mission (JNNURM) to upgrade the facilities. In Mumbai, a state-of-the-art sewerage system was developed, including a 2.6-km long trenchless tunnel. A Herrenknecht TBM 2500XH, equipped with 21 discs, was deployed to crack the basalt. Now, the tunnel is fully operational. There are similar opportunities in supply of oil and natural gas from coastline rigs, particularly in the Godavari basin in Andhra Pradesh.

"All these comprise the traditional business for tunnelling projects. These are turnkey projects offered by the government and private sectors to firms. However, what is lucrative for tunnelling companies are Build, Own, Operate and Transfer (BOOT) concessionaire projects. We could see plenty of them in the pipeline with the government implementing metro projects in as many as 16 cities of the country," says Sudarshan Narayan, Director, Axo Tunnels.

Incidentally, the country did take notice of the big tunnelling projects when the 11 km long Pir Panjal railway line tunnel began operations earlier this year in Jammu & Kashmir. At present, more than two dozen tunnelling projects in the transportation sector are in progress at various stages. The most ambitious among them is the 9.2 km-long Chenani-Nashri tunnel project connecting Jammu to Srinagar (National Highway 44). Upon completion, the 288-km distance between Jammu and Srinagar will be reduced to 238 km, but more importantly, the 10-hour journey will be covered in just about five hours. The National Highways Authority of India (NHAI) expects to complete the tunnel project work by end 2014.

The project, being executed by Leighton Welspun, involves construction of approximately 9 km of two-lane (13.3 m diameter) main tunnel along with parallel escape tunnel (5 m diameter) in the lower Himalayan mountain range. The tunnel is located at an elevation of 1,200 m with an overburden of up to 1 km and will be constructed using the NATM technique of sequential excavation and support.

Metro: Underground versus surface

The debate over running metro trains underground or on surface tracks is as old as the projects themselves. For, experts believe, underground or surface tracks depend on the density of the soil and rock in the subterranean region and on the need.

Underground metro is the costliest option – costing approximately Rs 300 crore per km for a hard geographical terrain like Bangalore. While elevated lines cost Rs 260 crore per km, the same for surface will be around Rs 180 crore per km. However, for a city like Bangalore, there is hardly space available on the surface (ground level tracks).

Though tunnels are expensive, they have its own advantages. Prof MN Sreehari, CEO, Consortia of Infrastructure Engineers, Bangalore, says: "While elevated metro will take into account the cost of acquisition of properties, shifting of utilities and construction hazards, underground metro could be slowed because of tunnelling will take more time."

On the technology verge

Several tunnelling companies have already set up shops in India in order to grab the projects. Some of these firms are even setting up plants to assemble TBMs instead of importing them from Germany and China.

Germany-based Herrenknecht, a pioneer in building TBMs, opened a new assembly plant in Chennai for the manufacture of cutter disks and a storage warehouse for spare parts. The plant will service the eight EPB shields the company has delivered to the Delhi Metro for construction of some 18 km of new metro running tunnels as well as future orders for Herrenknecht TBMs in India.

"The scope for tunnelling business in urban infrastructure and transportation is enormous in India. The Indian Railways wants to tunnel for close to 100 km in the Himalayas, particularly in Kashmir to reduce the travel distance. The Bangalore Metro expansion and Chennai Metro have significant tunnelling components. So naturally, India is an attractive market for international players in the sector," observes Ramachandran.

In Bangalore, two metro lines are under construction, the north-south and the east-west corridors. A joint venture (JV) of Taiwanese contractor Continental Engineering Corporation (CEC) and Indian contractor Soma is executing the east-west line. The 4.45-km of twin bore tunnels will be fully excavated by TBMs with the east and west ramps, the stations and a short pocket track being excavated by cut and cover. The tunnels will have a finished internal diameter of 5.6 m, lined with precast segments 1.5 m wide and in a five plus one arrangement. The segments are manufactured near the work site by Ya Li, part of the Far Eastern Group. The claim to fame of this tunnel project is that the 6.44 m Hitachi Zosen TBM is the first TBM to be used in a southern Indian state, and the first slurry TBM to be used in the country.

The Chennai Metro project is also on track with the commissioning of 3.34 km tunnel project being executed by the L&T and Shanghai Urban Construction Group joint venture.

"Many Indian infrastructure firms have entered into JVs with international tunnelling experts from China, South Korea and Japan for tunnelling projects. This is just the beginning because every city where metro is operational is expanding the network. Even cities like Bangalore and Chennai have already drawn up plans for Phase 2 and Phase 3 of the metro rail project where these firms will play an active role at the design stage itself. India is on the verge of a major revolution in tunnelling business," says Wugangbo Haibo, Partner, Xie Shanghai Tan Consultancy, which is exploring tie-ups between Indian infrastructure companies and Chinese firms with expertise in tunnelling.

When compared to China, which has more than 1,000 km network of road, railway, undersea and under river tunnels, India has just taken the baby steps. But the tunnelling market is poised for a huge growth in the coming years.