Phase 4: DMRC begins tunnelling work on Magenta Line extension
New Delhi: The Delhi Metro Rail Corporation (DMRC) on Friday started the construction work of the underground section of Phase 4 on the Janakpuri West – RK Ashram Marg corridor. As part of the work, construction of the D Wall, as well as the casting of tunnel segments of the 28.92-kilometre-long corridor, was also formally started.
"The work today commenced for the construction of D Wall at the Krishna Park Extension Metro station and the tunnel segments shall be used for tunneling with Tunnel Boring Machines (TBM) on a 1.4 kilometre stretch between Janakpuri West and Keshopur," the DMRC said in a statement on Friday.
The 28.92 km long Janakpuri West – RK Ashram Marg corridor is an extension of the Magenta Line and will come up with 22 stations. Construction work on this particular section had started in December last year.
In addition, this approximately two-kilometre-long stretch will also have the Krishna Park Extension station in between along with a 365-metre cut and cover open ramp near Keshopur leading to the elevated section. The Janakpuri West – RK Ashram Marg Metro corridor consists of a total of 7.74 kilometres of underground lines.
The commencement of this important component of construction work was also witnessed by DMRC's Managing Director, Dr Mangu Singh and other senior officials via video conferencing.
D Walls or Diaphragm walls are structural concrete walls constructed in deep excavation based projects. Diaphragm walls are often used at congested sites, close to existing structures, where there is restricted headroom, or where the excavation is of a depth that would otherwise require the removal of much greater volumes of soil. The excavated area is secured by these walls and then the construction work of the underground station is commenced. This technology has been used for Delhi Metro's underground stations right from the time when Phase 1 had begun.
The tunnel segments are being cast at the state-of-the-art casting yard developed at Mundka. The casting yard will make 2,100 rings for the tunneling work. This part of the construction work was awarded in December last year on an Engineering, Procurement and Construction (EPC) basis. Despite serious constraints like shortage of labourers and materials due to lockdown, the milestone could be achieved on time. On June 24, the casting work of u-girders for the same corridor was started.
Under Phase Four, 61.679 kilometres of new Metro lines shall be constructed across three different corridors comprising 45 Metro stations. Of this, 22.35 kilometres will be underground.