Tunnel boring machine (TBM) DZ1125 achieved its first breakthrough at Indira Gandhi National Open University (IGNOU) station for package DC-09 under Delhi metro project phase IV on March 18, 2025. It was commissioned in November 2023 at Chhattarpur Mandir station and traveled for 1,470 metres till IGNOU station.
Larsen & Toubro Limited (L&T) was awarded the contract for the same in March 2022. This development also marks the completion of tunneling works for the deepest underground stretch of the project.
Delhi metro project phase IV involves the development of a 112.4 km long metro rail network comprising six corridors with an investment of Rs 468 billion. The three corridors to be developed on a priority basis are Maujpur-Mukundpur (12.31 km), Janakpuri West-RK Ashram (29.26 km) and Aerocity-Tughlakabad (23.62 km). The other three corridors approved in 2024 by the central government are Inderlok-Indraprastha (12.37 km), Lajpat Nagar-Saket G Block (8.38 km) and Rithala-Narela-Kundli (26.46 km).