New Delhi: Delhi Metro on Thursday said that it has started the lowering work of the first-ever Tunnel Boring Machine (TBM) of Delhi Metro’s Phase 4 at Vikaspuri on the Janakpuri West – RK Ashram Marg corridor. As part of this tunnelling drive, two tunnels (for up and down movement) of a length of 1.4 kilometres will be bored between Vikaspuri and Krishna Park Extension.
The tunnelling work with the TBM is expected to start next month after the lowering and assembling of the giant 73-metre long machine is completed. These tunnels will be located between the Janakpuri West and Krishna Park Extension stations of the corridor. The tunnelling will start from Vikaspuri area in continuation of the Magenta line tunnel that has been already constructed for the presently operational Botanical Garden – Janakpuri West corridor.
The tunnel will be constructed approximately at a depth of 14 to 16 metres. About 2,040 concrete rings will be installed in these tunnels. Each tunnel will have an inner diameter of 5.8 metres. The entire tunnelling work on this stretch is expected to be completed in about 15 month’s time. The alignment of the tunnel will be along the Outer Ring Road.
As part of the Phase-4 work approved so far, about 27 kilometres of underground lines will be constructed. The Janakpuri West – RK Ashram Marg corridor will have underground sections of 7.74 kilometres in total.
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A TBM is a machine used to excavate tunnels with a circular cross-section through a variety of soil and rock strata. They can be designed to bore through anything from hard rock to sand. TBMs have revolutionised the way tunnelling work is done all over the world as now tunnels can be bored without disturbing the buildings and other structures on the surface.
TBMs are especially useful for underground tunnelling work in congested urban areas. DMRC has been using TBMs for its tunnelling work since Phase 1. In Phase 3, when about 50 kilometres of underground sections were built, about 30 TBMs were pressed into service in the national capital.
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