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Indian tonic

Delhi metro

Construction of phase 1 of the Delhi Metro is due to finish in September 2005. Bernadette Redfern caught up with the £1.4bn project.

The streets of Delhi are chaotic. Shops and market stalls spew out their goods into narrow, single lane streets where people, rickshaws, cars, cows, bicycles and construction traffic are all fighting for space.

Not a second passes without a horn blaring or a bell ringing. The bedlam is constant.

So the 24 hours-a-day noise of concrete pumps, excavators, trucks, tunnel boring machines and giant ventilation fans, all hard at work on construction of Delhi Metro, are hardly audible above the din of every day life.

The first £1.4bn phase Delhi Metro, consisting of three lines totalling 68.3km of track and 59 stations, is scheduled to be completed in September 2005.

Main consultant is Japanese firm Pacific Consultants International with US firm Parsons Brinckerhoff, Japan Railway Technical Services, Japan's Tonichin Engineering, and local Rail India Technical & Economic Services in support.

Less than half of it is built so far, and to spur the workforce on, every site has a prominently displayed clock counting down the days left to the contractors.

Everyone, no matter what their job, knows how much time there is to go, says Delhi Metro Rail Corporation (DMRC) communications chief Anuj Dayal.

'It is a motivational tool.'

Construction is going full pelt on an 11km underground section of the project, known as line two, which runs north to south through the very centre of Delhi. Work has been packaged into two contracts - a joint venture of Japanese firms Kumagai Gumi and Itochu, with Swedish giant Skanska and Indian firm Hindustan Construction, is working on the northern section from Vishwavidalaya to Delhi's central bus terminal. German firm Dyckerhoff & Widmann, major Indian groups Larsen & Toubro and Ircon International, and Japanese contractor Shimizu are tunnelling from the bus terminal south to the Central Secretariat.

Three tunnel boring machines (TBMs), cut and cover and New Austrian Tunnelling Method (NATM) techniques are being used in a frantic effort to ensure that all tunnels and stations are ready for handover next autumn. Line one was completed in 2002 and construction of line three has yet to start (see box).

The TBMs, which are being operated by the Dyckerhoff/ L&T/Ircon/Shimizu JV, got off to a good start in soil but have hit hard quartzite rock where progress has been disappointingly slow.

'In soil our progress has been very good - we've been completing a maximum length of 30m, which is 25 rings, in 24 hours. But in rock we are not doing so well, digging only 1m or 2m per day, ' says DMRC chief engineer Kamal Nayan.

'The rock is highly fractured and full of softer sandstone - schist - which makes the face uneven.

The machine is veering too much and hitting the rock too hard and we are constantly having to change the disc cutters, ' he sighs.

This is a particular problem in the tunnel which will link Delhi Main Station to Chawri Bazar to the north. The TBM was moving southwards from Delhi Main but ground to a halt, the going was so hard. To rescue the programme - and the machine - the contracting joint venture is now digging from Chawri Bazar using NATM.

Tunnels are 10m wide by 9m high. A team of 100 men is employed on each face. Labour is cheap in India and is supplied on demand to the major contractors by specialist agencies.

Excavation of the tunnel advances in 1m stages. First, the top 5m of the face is cut.

'Immediately after excavation the face is stabilised with primary support in the form of shotcrete sprayed over wire mesh and steel girders, ' says Nayan. Next, another 2m bench is excavated and supported, and finally the last 2m to the invert is dug. 'We do it in three phases to ensure minimal damage to surface structures through subsidence, as well as for the safety of people involved in the construction, ' says Nayan.

A 50mm tolerance has been allowed for deformation.

Chawri Bazar station itself presented a major challenge to engineers. The area is one of the busiest markets in India and so congested that it was impossible to clear a space large enough to dig a station box. To solve the dilemma engineers decided to excavate two 30m deep shafts 150m apart, creating two mini stations, providing separate platforms for east- and west-bound trains. The first shaft at Hauz Quazi Chowk was sunk through the local cricket pitch, which the DMRC promises will be restored to full bowling and batting form upon completion. And the second shaft has seen demolition of the Amar Cinema, which will also be reinstated.

There is no doubt that the biggest worry for everyone working on the project is getting it finished on time. The last metro built in India was in Calcutta, which 'was only 16km long but took 25 years to build and cost 12 times the original estimate. It was a bad experience and the whole city became fed up with it. We cannot let this happen in Delhi, ' says Dayal.

All India's major cities are looking to Delhi Metro to be a success. Chennai, Hyderabad, Bangalore and Ahmedabad all want a metro but are waiting to see how Delhi goes before committing to anything.

Ten year plan

Delhi Metro Rail Corporation (DMRC) was formed in May 1995 by Delhi state and Indian central government. Despite a late start due to political problems the DMRC felt it was important to stick to the published completion date of September 2005 in order to avoid the public outcry and ridicule that dogged the Calcutta Metro which took 25 years to build and went 12 times over budget.

Design contracts were awarded in 1998 to a consortium led by Japanese consultant Pacific Consultants International. Eight main contracts have also been awarded for construction and to date 170 contractors and suppliers have been involved in the project.

The master plan is to build 244km of track to join up the radial arms of Delhi, starting with 68.3km in the first phase. Phase 1 consists of three rail lines, the first of which - 28km of elevated track - was finished in early 2002.

It runs from the west into central Delhi. The second line, running 11km through tunnel north-south under central Delhi, is now under construction. Construction of the 29.3km long, elevated line three is yet to begin.

Still standing

Throughout Delhi are ramshackle buildings. Some are 150 years old with shallow foundations and others have none at all. An intensive monitoring operation has been carried out consisting of over 1,000 survey points to ensure that nothing falls down unless it is supposed to. 'We have carried out several controlled collapses and had to evacuate a few buildings, ' says Dayal.

The digging of unauthorised wells has also required lots of additional survey work but so far there have been no collapses resulting from encounters with uncharted shafts.

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