On Friday, the Delhi Metro Rail Corporation (DMRC) acquired an important milestone as the first stretch of tunnel of its phase-4 project got finished. Anuj Dayal, Executive Director (corporate communications), DMRC, told the media that the tunnelling stretch was completed at Krishna Park Extension on the Janakpuri West – RK Ashram Marg corridor, which is an extension of the Magenta Line (Botanical Garden-Janakpuri West). Dayal said that a Tunnel Boring Machine (TBM) broke through the 1.4 km stretch on Friday in the presence of DMRC’s managing director Mangu Singh. The main tunnelling work on this stretch started in April after achieving the initial dr4e. Despite many restrictions imposed by the Covid-19 pandemic, work was continued, and this significant milestone could be attained, he said, adding that a 73 m long TBM was utilised for the purpose. He said that two parallel tunnels for up and down movement were being made on this stretch, which is a part of the 2.2 km long underground section between Janakpuri West and Keshopur. He said that tunnelling work on the other parallel tunnel would start shortly. The new tunnel is a continuation of the earlier Magenta line tunnel and has been constructed at a depth of about 14 to 16 m. More than a thousand rings have been set up in the tunnel. It has an inner diameter of 5.8 m. The tunnel alignment moves along the Outer Ring Road and below the multi-storeyed constructed structures. The tunnel has been constructed with the Earth pressure balancing method, with concrete lining made up of precast tunnel rings. These concrete segments were fixed with a steam curing system to attain early strength. All required safety precautions were taken while developing the tunnel, he said. As part of the phase-4 work nodded so far, approximately 27 km of underground lines will be built comprising the 7.7 km underground stretch, which is a part of the Janakpuri West –RK Ashram Marg corridor. Image Source Also read: Delhi metro phase 4 gets six bidders for RSS AMS electrification