The tunnelling industry in India has given no indication of collapse, despite the recession. Speaking in 2009, Ruben Patel, managing director of Patel Engineering, a significant contractor in microtunnelling and many other sectors, pointed to government projects as the reason for his company’s ability to prosper in the economic downturn. He added, “In a worst case scenario, these projects may get delayed to a certain extent. By contrast, private sector projects are severely affected due to the liquidity crisis.”

A focus on metro…
If government expenditure is key for the survival of the tunnelling industry in a market hit by recession, the Indian Government is certainly not shirking from the task. Combining state and national funds with foreign investment—particularly from the merged Japan International Cooperation Agency (JICA) and Japan Bank for International Cooperation (JBIC)—a lucrative funding packet is available for many key infrastructure projects. The continued heavy investment in metro rail transport systems in particular is a clear statement of Indian intent. The industry will be buoyed and the roads shall be relieved, delivering economic benefits on several fronts.

To write that metro projects are thriving in India at the moment would be a monumental understatement. Included in a list of 19 cities approved for a rapid mass transit project under the Jawaharlal Nehru National Urban Renewal Mission are: Delhi, Calcutta, Mumbai, Chennai, Ahmedabad, Hyderabad, Lucknow and Bangalore with many more proposed.

Although a detailed description of all of the projects would be impossible, the work on the Delhi Metro deserves a special mention, as it is the largest of the infrastructure projects. The recent phase two has been funded by a long-term soft loan from JBIC. With the total of all phases valued at around an estimated USD 10.3bn and the project spanning a quarter of a century, the network will consist of an impressive 413km total length of metro line built across the four phases. Completion is expected by 2021.

…especially Chennai
The Chennai Metro is a good case in point of government resources working with foreign funding in the public interest, as a public private project. Valued at approximately INR 14,000 crores (USD 3.1bn), 41 per cent of the cost will be met directly by the Government of India and the state Government of Tamil Nadu on a 50-50 equity basis. The remainder will be funded by a loan granted by JICA, broken down into a 0.01 per cent interest rate for consultancy services and a rate of 1.4 per cent for construction and procurement services. The loan will be repaid over 30 years with a moratorium period of 10 years. The loan was signed by the governments of India and Japan in Tokyo on 21 November 2008, despite the Chennai Metro project not being finally approved by the Government of India until early the following year, on 28 January 2009.

Excavation of the running tunnels will be undertaken by ‘latest TBMs’, with the stations being excavated by cut and cover. This is a problem for traffic on the arterial roads of Chennai where the stations will be located as the process could take around two years to complete. Great importance is placed on this; a retired local police officer will be employed to liaise with the City Police Headquarters on traffic management issues.

The tunnel will run 14.3km in corridor one with the remaining distance elevated, and 9.7km in corridor two, with, again, the remaining distance covered by elevated track. The average depth will vary from 15 to 17m from rail level and the tunnel will have an internal diameter of 5.8m. The minimum surface to tunnel clearance of 9m means the TBM will not be at risk of clipping utility tunnels.

Tunnelling is scheduled to begin at the start of 2011 with cost anticipated to be around INR 300 crores (USD 66M) per kilometre of underground track and INR 100 crores (USD 22M) per kilometre of elevated track. A preference for the least obstructive option for the narrow roads is quite clear, despite the tripled costs.

“A single six-coach metro train will remove 16 buses or 300 cars or 600 two wheelers from the roads at peak hours. The metro is expected to remove 13 lakh (1.3M) passengers per day from the roads by 2026 in Chennai alone,” said chief public relations officer for Chennai Metro, S Krishnamoorthy.

Construction of the first phase of the project should conclude in 2014 or 2015.

Hydroelectric politick
Hydroelectric power has traditionally been another area of interest for the Indian government. Early successful projects such as the Pykara Damprovide inspiration for more recent endeavours such as the USD 1.57bn power plant at Dhemaji, the USD 1.3bn Kalai plant on Lohir River and even across the border, with the USD 2.6bn, 1,200MWKohala hydroelectricity plant in Pakistan.

Chief among these in terms of size, however, is the Subansiri Lower Hydro Electric Power Plant project on the river Subansiri, close to North Lakhimpur, that forms the border between the states of Arunachal Pradesh and Assam in northeast India.

The client is the state-owned National Hydro Power Corporation (NHPC) that describes the work as the largest such project ever undertaken in India. Engineering, procurement and construction contracts were awarded in January 2004 and April 2005. Soma is the contractor constructing the dam and tunnels.

The plant features a dam rising 116m from the riverbed and was expected to cost INR 6,285.33 crores (USD 1.38bn) by the 2002 estimate and requires the construction of eight 9.5m diameter headrace tunnels of horseshoe shape with lengths ranging from 608 to 1,168m, eight 9.5m diameter surge tunnels of horseshoe shape with lengths between 400m and 485m and eight horseshoe/circular pressure shafts with diameters varying between 7.0m and 9.5m, and lengths of 168-190m. There will also be a 205m long tailrace channel.

A K Biswajit Das, executive director of Soma, wrote in his paper ‘Geotechnical Assessment of Diversion Tunnels of Lower Subansiri Hydel Project, Assam’ that the rock encountered was “medium-to-coarse grained Middle Siwalik Sandstone and the overall tunnelling condition was fair to good.”

One challenge is that the nearest railhead to the local town is in Nagaon, approximately 262km away by road. Another problem is the heavy rain. An annual average rainfall of 4,600mm results in the shutting down of all works between May and September.

The project will create an estimated 2,000MW generating capacity when completed, split between eight Francis turbines, and is scheduled for completion by the end of 2012 in a memorandum of understanding made in November 2010; however controversy surrounds the project.

In 2009 a committee of eight people was set up to investigate the Subansiri project. Drawn from the Department of Transport among other organisations, it accused the project of ‘gross inadequacy’ of design. Environment chief of NHPC, Vipin Kumar responded saying, “there has been a lot of confusion and apprehension about the ecological toll but there is no scientific basis to that.”

Jairam Ramesh, state Minister of Environment and Forests called for a halt to construction, accusing the government of using Arunachal Pradesh as a ‘pawn in the race with China.’ Arunachal Pradesh is a region politically charged on the international level as it is also claimed by China as part of South Tibet.

Water supply is another important facet of the Indian tunnelling business whether inked to hydroelectric schemes or as standalone projects. Several are complex and involve tunnelling at record lengths through tough ground conditions.

Himalayan highways
Transport investment in India does not just concentrate on the accessibility of densely populated districts in an urban sprawl. The Patnitop and Rohtang mountain tunnels were designed to alleviate the use of the high, snaking mountain roads that are the traditional route over the Himalayas.

IL&FS Transportation Networks awarded the USD 570M contract for the Patnitop tunnel. This is a privately funded venture, however the National Highways Authority of India will award a semi-annual annuity for the infrastructure and services. The Border Roads Organisation, an inter-ministerial civil engineering group that works in conjunction with the Indian Army, awarded the Rohtang tunnel contract. These tunnels will hopefully show the merits of sequential excavation in the geologically dynamic Himalayas.


Launching the 10m diameter Robbins double-shield TBM for the 19.2km long Pula Subbaiah Veligonda Tunnel No. 2 in a water supply scheme. It features Robbins’ longest single-flight belt conveyor A busy street scene from Chennai shows the need for a metro The perilous route to Patnitop tunnel site Early groundworks in preparation for the Patnitop Tunnel