The Delhi Metro Rail Corporation (DMRC) and contractor Larsen & Toubro have achieved a major construction milestone on Phase 4 with the completion of a 1.47km long underground tunnel between Chhatarpur Mandir and IGNOU Station on the Tughlakabad – Aerocity corridor as part of the Phase 4 Golden Line.
The breakthrough of the EPBM at the IGNOU Station site of the Delhi Metro took place in the presence of Shri Anand Mohan Bajaj, Deputy Comptroller & Auditor General, Commercial, Shri Pramod Kumar, Additional Deputy Comptroller & Auditor General, Dr. Vikas Kumar, MD, DMRC and other senior officials.
The tunnel breakthrough was achieved using a mammoth 97m long TBM, with the breakthrough of the other parallel tunnel planned for March’25.
This new tunnel has been constructed at an average depth of approximately 26m (min depth 15m and a maximum of 36m) making it one of Delhi Metro’s deepest tunnels.
Some 1048 precast concrete tunnel rings have been installed in the tunnel, to an inner diameter of 5.8m. The tunnel rings were cast at a fully mechanized casting yard set up at Mundka. The concrete segments were cured with a steam curing system to achieve early strength.
The tunnel drive started on 4th December, 2023 and various challenges, including a steep gradient along with a varied geology comprising mica and hard rock were encountered damaging the screw auger which needed to be replaced during the drive.
As part of the Phase 4 work approved so far, 40.109km of underground lines are being constructed. The Aerocity-Tughlakabad corridor has underground sections totalling 19.343km.
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