New Delhi [India], June 25 (ANI): The Delhi Metro Rail Corporation (DMRC) has achieved a significant milestone in the ongoing Phase 4 expansion by completing a major underground tunnelling task between Kishangarh and Vasant Kunj stations on the Tughlakabad-Aerocity corridor of the Golden Line.

The breakthrough was achieved when a Tunnel Boring Machine (TBM) completed its journey this morning at Vasant Kunj Metro Station after constructing a 1,550-metre-long tunnel, using a 91-metre-long TBM.

The DMRC took to social media to announce about this development. In a social media post on X, it stated, 'DMRC Completes another Major Tunnelling Milestone on Phase 4 Golden Line; Breakthrough at Vasant Kunj Metro Station. The Delhi Metro Rail Corporation (DMRC) today achieved a major construction milestone in Phase 4 with the completion of an underground tunnel between Kishangarh and Vasant Kunj Station on the Tughlakabad-Aerocity corridor.'

'A Tunnel Boring Machine (TBM) broke through this morning at Vasant Kunj Station after boring a 1550 meter-long tunnel. This tunnel breakthrough was achieved using a mammoth 91-metre-long TBM. Two parallel circular tunnels for up and down movement are being constructed on this stretch as part of the Aerocity-Tughlakabad corridor. The breakthrough on the other parallel tunnel was achieved on 06.03.2025,' it added.

https://x.com/OfficialDMRC/status/1937825334012830004

According to the DMRC, this new tunnel has been constructed at an average depth of approximately 22.86 meters (min depth 15.48 mtr & max. 30.25). About 1105 rings have been installed in the tunnel, with an inner diameter of 5.8 meters.

The tunnel has been built using the proven technology of EPBM (Earth Pressure Balancing Method) with a concrete lining made of precast tunnel rings. These 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.

All necessary safety precautions were taken during the construction of the tunnel below the existing structures. Ground movements were monitored with highly sensitive instruments fixed on nearby structures, ensuring that there was no settlement anywhere, the DMRC stated.

As part of the Phase 4 work approved so far, 40.109 kilometres of underground lines are being constructed. The Aerocity-Tughlakabad corridor has underground sections totalling 19.343 kilometres.

A TBM is a machine used to excavate tunnels with a circular cross-section through various soil and rock strata. They can be designed to bore through anything from hard rock to sand. TBMs have revolutionized tunnelling work worldwide, enabling tunnels to be bored without disturbing buildings and other surface structures.

TBMs are particularly useful for underground tunnelling work in congested urban areas. DMRC has been using TBMs for its tunneling work since Phase 1. In Phase 3, when approximately 50 kilometres of underground sections were built, about 30 TBMs were deployed in the national capital. (ANI)