The TBM broke through at Chhatarpur Mandir Station last week after completing an 860m-long drive.
Two parallel tunnels for up and down movement have been constructed on this stretch as part of the Aerocity–Tughlakabad corridor. The breakthrough on the parallel tunnel was achieved on August 21.
The 97m-long EPB TBM constructed the tunnel at an average depth of approximately 12m. About 613 rings have been installed in the tunnel, forming an inner diameter of 5.8m.
The tunnel rings were cast at a fully automated casting yard at Mundka.
The tunnelling work involved several challenges, such as shifting a 66KV electrical HT line and passing below the existing Yellow Line viaduct without disrupting metro operations on the line.
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.
Last month Afcons made the first simultaneous twin tunnel breakthrough on Phase 4 when TBMs Bhoomi and Srishti emerged at the same time at Pulbangash Metro Station.
All phases of the Delhi Metro have been excavated by TBM. In Phase 3, which comprises around 50km of tunnels, about 30 TBMs were deployed.
