Delhi Metro Phase-3: A feat of engineering
The DMRC stuns with its precision construction at four upcoming interchange stations that will make the Metro ride even more convenientdelhi Updated: Aug 19, 2016 16:52 IST
In four months from now, most of the Delhi Metro stations constructed under Phase-3 would be thrown open for commuters. Thousands of professionals including engineers, architects, managers, skilled and unskilled labourers have put in endless hours of work to give a world-class experience to commuters in the Delhi Metro. The construction of four interchange stations in south Delhi was a challenging task as two lines meet here.
The Kalkaji Mandir Metro station is all set to emerge as a premier interchange hub after the completion of Phase 3 with direct connectivity to Faridabad and Noida. The new station will be 17m deep whereas the present station is an elevated one. A foot overbridge (FoB), about 260m long, will connect the paid area of the new station with the old.
The new station will have an upper concourse in addition to the main concourse. Trial runs have begun on this section between Kalindi Kunj and Kalkaji Mandir last week. Kalkaji Mandir on the Janakpuri West-Botanical Garden corridor is being developed as interchange station so that commuters travelling from Gurgaon on the Yellow Line can avoid Rajiv Chowk and change trains at Hauz Khas to travel to south Delhi and Noida.
“We have used the New Austrian Tunnelling Method (NATM) between Kalkaji Mandir and Okhla Phase-III on the Magenta Line to pass below the presently operational Nehru Place-Kalkaji elevated section of the Mandi House-Badarpur Metro corridor (Violet Line),” he said.
The tunnel between Kalkaji Mandir and Okhla Phase III passes below piers 135 and 136 of the Violet Line and the distance between the two piers is 28m. It would have been impossible to construct twin tunnels within such space. Therefore, a decision was taken to construct a single tube twin tunnel through which both the tracks will pass using the NATM technology, he said.
Also, tunneling was required for only a short stretch of 176m. Therefore, it would have been inconvenient and time consuming to insert a Tunnel Boring Machine (TBM) and construct separate shafts for insertion and retrieval of the TBM, he added.
INA will be an interchange station between two lines — the under construction Mukundpur-Yamuna Vihar metro corridor and the existing Yellow Line (Huda City Centre-Samaypur-Badli).
This is the first platform of Delhi Metro where commuters will get direct access to an underground platform unlike other interchange stations like Rajiv Chowk, where people have pass through the concourse of the Metro station (where two access to platforms meet) if they want to go to the underground platform. It was a huge challenge here as the new station is being built over the existing Metro tunnel that connects INA with AIIMS along the Yellow Line.
There are going to be three levels in this underground interchange station – the platform for Pink Line, the concourse and the platform for the Yellow Line. It is for the first time that a station is being built over the existing tunnel connecting the operational Metro stations.
“Commuters who have to change trains at INA will get direct access to the new line through the concourse below the new platform, which is being built at a depth of only seven metres from the ground,” said an official of DMRC.
The DMRC had to execute this major design change as there was a sizeable height variation between the existing INA station and the upcoming station. “The DMRC had to modify the station design to adjust to the new circumstances,” the official said.
Cut and cover tunnel technology is being used in the existing operational tunnel. “If you see the layout of the two Metro corridors, they form a plus sign. So, there is one point where trains of both the lines and the concourse will simultaneously operate on top of each other,” he said.
The Hauz Khas Metro station will be a major interchange point between the Yellow Line and the upcoming Magenta Line between Janakpuri to Botanical Garden corridor.
Constructed 29 metres below the ground, the new Hauz Khas station has surpassed Chawri Bazar station built at a depth of 25 metres. The new Hauz Khas station will also be the first one to have five levels. There will be three intermediate levels, followed by a concourse and a roof. At present, Metro stations in Delhi and NCR have a maximum of three levels.
“For the construction of the new station, it was not possible to go below the existing station as its foundation was just 32 metres deep and it is surrounded by the Outer Ring Road. Therefore, if the new station had to be constructed below the existing station, we would have to go deep up to 42 metre. So, the 265m-long new station was built adjacent to the existing station at a depth of 29m. A subway has been built to connect the new and the old stations,” said a DMRC official.
Right now, there is a subway in the unpaid area of the station. The same will be converted into a paid subway connecting the old and new stations. It will be 40m long and 12m wide.
After the inauguration of this link, the approximate commute time between Huda City Centre and Botanical Garden after changing the train at Hauz Khas will be about 50 minutes. Presently, a it takes about 1.5 hours from Huda City Centre to Botanical Garden after interchanging at Rajiv Chowk.
The Lajpat Nagar Metro station on the ITO-Faridabad corridor (Violet Line) is being converted into an interchange station to connect with the upcoming Majlis Park-Shiv Vihar corridor. With the opening of this station, commuters coming from Shakurpur, Punjabi Bagh, Rajouri Garden or Mayapuri in west Delhi and north Delhi’s Majlis Park, Azadpur or Shalimar Bagh areas will be able to travel directly to Lajpat Nagar.
In addition, they will be able to change trains here to go to Faridabad or Janpath, Mandi House and Old Delhi areas like Delhi Gate, Jama Masjid, Red Fort, Kashmere Gate. The new station at Lajpat Nagar will be underground and will be connected with the existing elevated station through a 90m long foot overbridge (FoB).
“Due to space constraints as there is a market, a busy road and the existing station, the two stations have not been interlinked,” said a DMRC official. Ideally, at most of the interchange stations, the two stations are linked internally and new station is usually constructed below the existing one.
“Since we did not have space below the existing station, the gate of new station will be around 100 metre away from the existing one. The upcoming station is underground so when passengers will come from there, they can take the FoB, currently under construction, to go to the first floor of existing station,” he added.
The new station will be 15m deep while the existing station is at a height of about 12m. The new station will have two additional entry/exit points catering to the Lajpat Nagar market as well as residential areas. Another entry/exit point will also be provided near the entry/exit point of the existing station.