New Delhi: The Delhi Metro Rail Corporation (DMRC) has now successfully wrapped up all the tunneling works of Phase 3 with the completion of a 1.25 kilometre long tunnel between Vasant Vihar and Munirka on the Janakpuri West – Botanical Garden Magenta Line.
The Tunnel Boring Machine (TBM) boring the tunnel from Vasant Vihar broke through at Munirka last evening in the presence of DMRC’s Managing Director, Dr. Mangu Singh and other senior officials. The work on this 1.25 kilometre long tunnel had started in the month of October, 2015. The tunnel consists of a total of 904 rings and has been constructed about 20 metres below the surface.
With this tunnel breakthrough, DMRC in Phase 3 has now completed one of the largest ever tunneling projects taken up in any urban area all over the world where a record 30 TBMs were used to bore close to 80 kilometres of underground tunnels (combining the length of both tunnels for to and fro movement of trains). The total underground corridor length in Phase 3 including the stations is about 54 kilometres.
The quantum of underground work in Phase 3 can be gauged from the fact that in the last phase of Delhi Metro’s construction, only 35 kilometres was underground and in Phase 1, the underground component was 13 kilometres. Therefore, the underground work of Phase 3 was even more than the combined work undertaken in the first two phases.
On the 38 kilometre long Janakpuri West – Botanical Garden corridor where the tunnel breakthrough took place yesterday, about 23 kilometres are underground. The tunnelling work on this corridor had multiple engineering challenges. The new tunnels passed below already operational elevated viaducts of Delhi Metro at three locations (at Janakpuri West below Blue Line, near IGI Airport below Airport Line and near Kalkaji Mandir below Violet Line).
At Hauz Khas, the new tunnel also passed below the already operational tunnel of Delhi Metro’s Yellow Line. A 1.4 kilometre long tunnel between Shankar Vihar and Vasant Vihar on this section was also fraught with challenges as it passed below the rocky Aravali ranges and special Rock TBMs had to be pressed into service for the drive.
On the 59 kilometre long Majlis Park – Shiv Vihar Pink corridor, about 19 kilometres are underground. This is the longest ever Metro corridor of the DMRC network. On this section, the new tunnels have passed below already operational viaducts at three locations (at Azadpur below the Yellow Line, Netaji Subhash Place below the Red Line and at Lajpat Nagar below the Violet Line). The new tunnel also passed below the operational Metro tunnel of Yellow Line at INA.
Delhi Metro’s longest tunneling drive of 1.6 kilometres from Ashram to Nizamuddin also falls on this section. All the tunneling work on this line has also been completed. However, at some locations, the TBMs are now being retrieved following the completion of work. The tunneling work on both the Magenta and Pink lines had to face multiple challenges since these corridors mostly pass below the arterial Outer Ring Road and Ring Road of the city, which have heavy traffic round the clock.
For countering all the above mentioned challenges, elaborate instrumentation for round the clock monitoring was done to ensure that there was no settlement of land anywhere or damages to the structures above. As the tunneling work proceeded below the elevated viaducts and the Metro tunnels of Yellow Line at Hauz Khas and INA, services on these operational sections were not hampered even for a minute.
The 9.37 kilometre long Central Secretariat – Kashmere Gate corridor is also entirely underground. While the section up to ITO has already been opened, trial runs are in progress on the remaining stretch up to Kashmere Gate. Tunneling was extremely difficult on this section as well since almost the entire alignment is dotted with heritage monuments of great historic importance. Moreover, the areas in old Delhi are extremely crowded with many dilapidated buildings, which are more than a century old.