Despite encountering many challenges on the 22.7 km journey from New Delhi railway station to Dwarka Sector 21, Delhi Metro Rail Corporation is hopeful that the line will be ready in time for a September 2011 opening.
“Till date we have been able to meet all the deadlines. Over 90 per cent of the civil work is over and we have been delivering on schedule. There is not reason why we will not be able to hand over the line to the contractor on time,” said DMRC engineer who is in charge of the segment between New Delhi railway station and Talkatora.
However, there were many obstacles in the successful completion of the line that will be handed over to a consortium of Reliance Energy Limited and CAF of Spain to run.
To begin with the contract for civil construction of the line known as the Airport Express Link with a commissioning date of September 2010 was awarded only towards the end of 2007, which meant a race against time for DMRC.
Another major challenge was the geology of the areas that the metro had to pass through. “The contract was awarded late and we had less than three years to build from scratch. The biggest problem was the geology, it alternated between rock and soil conditions and we were constantly changing the cutters of the Tunnel Boring Machines and switching from one technology to another,” recalled Mr. Garg.
To meet the deadline, DMRC had to employ more manpower and work round-the-clock. “In the New Delhi railway station and Talkatora stretch alone we had 4,000 people working in shifts round-the-clock. If you were to hazard a guess for the entire line, the number will be much higher. In terms of the man-hours spent, this line will probably have the highest figures,” he said.
More challenges came in the form of vast stations that required almost double the excavation work. “Although the number of stations was less, we had to perform double the excavation work at the stations because of their sheer size. A normal station requires up to two lakh cubic metre of excavation, this line required double, the New Delhi station alone required 4.5 lakh cubic metre of excavation work,” said Mr. Garg.
At the New Delhi station, which is 45 metres below the surface, the DMRC teams had to confront water at high pressure. “The water table was at a depth of about 10 metres and there was immense pressure exerted by the water. Luckily for us, the tunnel boring machines to withstand this pressure and forge ahead.”
Once the line neared the Ridge area, the DMRC’s team had to rework on the alignment what with the Delhi Urban Arts Commission declining to give consent of the design conceived by DMRC.
The DUAC had refused to give its consent to metro going elevated from Mother Teresa Crescent all the way up to Dhaula Kuan. “The DUAC’s decision meant more work for us, but we were ready with the technology. This is one line where we have used all the methods, the cut and cover, the TBM and the New Austrian Tunnel Boring machine. In fact the longest stretch measuring up to 2 km using a NATM is on this line,” said Mr. Garg.
Six stations en-route
The New Delhi railway station to Dwarka Sector 21 line will have the trains running at a very high speed of 135 km/hr. The journey between the New Delhi station to the airport will be 18 minutes and the initial frequency of the trains will be 10 minutes.
There will be six stations -- New Delhi, Shivaji Stadium, Dhaula Kuan, Delhi Aerocity, IGI Airport and Dwarka—with check in facility available at New Delhi and Shivaji Stadium.
These stations will allow commuters to check in baggage and collect the boarding pass and shop at the CAT and catch the high speed metro to the airport terminal.