The Delhi Metro Rail Corporation (DMRC) has completed tunnelling on its deepest underground stretch in Phase 4, achieving a tunnel boring machine (TBM) breakthrough at IGNOU station site.

This tunnel, part of the Aerocity-Tughlakabad Corridor (Golden Line), connects Chhatarpur Mandir to IGNOU at an average depth of 27 mtrs., reaching up to 39 mtrs. 

The parallel tunnel was completed on 25 February, 2025, marking the conclusion of tunnelling for both tracks. 

DMRC used the earth pressure balancing method (EPBM) to install 1,048 precast concrete rings with an internal diameter of 5.8 mtrs. 

Overcoming geological challenges like steep slopes, mica, and hard rock, the TBM’s screw auger was damaged and replaced during operations.
CM Rekha Gupta and Environment Minister Manjinder Singh Sirsa attended the event.