The Delhi Metro could equal the present day London Underground network in 13 years. The sprawling city needs it. And the pride of the engineers making it happen is clear.

"Spreading risk. That is how we have been able to build such a project at this rate," says Mohan Gupta, metro and civil geotechnical divisional director for Mott MacDonald. "The Delhi Metro has been split into packages of three to 4km. You can get all elements of tunnelling in these sections: TBM drives, cut and cover stations and so on."

The various phases of the Delhi Metro, while prioritising vital districts of the city, have been planned in a web configuration.

Phases one and two focussed on constructing the radial routes spreading outwards from a centre point.

Phase three will add circles to connect these radial routes and phase four, if it goes ahead, will extend the radials while adding more circle routes.

Phase one
Phase one kicked off in 1998 with the least tunnelling of all the phases. Some 13km of the 65km, three-line central Delhi network were underground.

Project developer the Delhi Metro Rail Corportation [DMRC] estimates the cost of this portion at INR 105.7bn (USD 1.95bn).

Gupta says that the decision to go underground is not the first choice for Delhi, and it is a decision entirely based on cost. The price of an elevated line is roughly 10 per cent that of a tunnelled line, so if the government is in a position to acquire land along the alignment, it prefers to go over it.

Per kilometer, Delhi Metro tunnels cost around INR 2.5bn (USD 46M), while elevated line sets DMRC back some INR 250M (USD 4.6M).

Completed in December 2005 just about three years ahead of schedule and on budget, Businessweek reported at the time that the achievement was a miracle in a country previously renowned for inefficient public works. Like many others, its praise for the miracle worker fell on DMRC’s former director.

Phase two
T&TI reported the start of phase two tunnelling in 2008 with the lowering of two 6.54m-diameter Herrenknecht EPBMs. Some 14 machines were launched that year, with excavation due to be completed on all drives by or during 2009.

The 30 tunnel drives called for this record-breaking number of TBMs working in a single city. Of the 124km to be added to the metro in this phase, 35km were underground. Driven 16km by TBM and 2.8km by NATM. The 20 underground stations were constructed by cut and cover, twice as many as in phase one.

Gupta recalls the Airport Express Line (orange line on the map, above) as giving him important life lessons. "In most situations, preliminary designs have been carried through to construction. On the Airport Express Line however, the client said alluvium soils reached down to around 30m, and the bid by the contractor was priced at that.

"When digging began, it was found that the rock was higher than expected. Where the station was to be located, rock was 8m below the surface. We wasted two to three months on investigations and changing subcontractors and so on. Finally Airport Express contract C1 was delivered on time by the contracting JV Alpine, Samsung and HCC with Mott MacDonald as designer."

Risk in India
One of the problems with doing business in India is the amount of risk being placed with the contractor. Gupta says employers generally ask contractors to design all risk into the bid.

He says, "This is an issue as contractors often seem to face difficulties because of this and are not making very big profits in India. The client is not legally allowed to pay more [if circumstances change].Professional understanding can [sometimes make this] different, but I do not know of any cases to comment on.

"In the case of the Airport Express I was only involved on the technical side and so not overly affected [by the unexpected conditions]. Although with the balance of risk being entirely on the contractor, it is important that risk information is accurate and shared.

"I think the Airport Express was an example of lack of information at concept design and not intentional withholding of information," says Gupta."

T&TI reported in November 2010 that DMRC had ordered USD 2.53M in penalty fares against the developer and contractor for the project Delhi Airport Metro Express, which has a 30 year concession to operate the line once completed. The fine was for a failure to obtain safety clearances from the Commissioner of Metro Rail Safety before the line could be allowed to operate, resulting in delays.

Phase three
For phase three, around 45km of underground lines will be built with 31 underground stations. DMRC spokesman Anuj Dayal says that this will be almost as much as the underground work from the previous two phases combined. For the first time, Delhi Metro lines will have to cross. Some 25 TBMs will be used on the project, the first two of which have already been lowered to work on the north-south Violet Line.

Dayal says the corporation will set up a centralised TBM control room for this phase. The facility will monitor the ‘fuctioning’ of the TBMs with GPS technology, enabling coordination of progress. Bidding for phase three will be over by the end of the year.

Dreams of the future
Phase four planning is in place, but as funding has not been finalised, no bidding information has been released to the market. Gupta is confident it will go ahead, with completion by 2020.

"Everyone involved in the project has a common goal," says Gupta, "of course we are very proud of what we are doing. We’ve constructed over 190km of metro in ten years, the highest rate in the world. I remember back in 2001 when I had little experience in underground work. I was worried like some others, we had professional doubts, but we took up the challenge and it has happened.

"By 2025 and with the successful completion of phase five, we will have connected the entirety of Delhi and its satellites with over 400km of metro."