J Kumar Infraprojects has achieved the first breakthrough on the Delhi Metro Phase IV Silver Line.
The Terratec EPB TBM, named Narayani, completed its first drive after excavating a 1.6km-long tunnel on the Vasant Kunj to Mahipalpur section of the Aerocity–Tughlakabad corridor of the Delhi Metro Rail Corporation project.
As it advanced, the 6.61m-diameter machine installed 1,400mm-wide universal reinforced concrete lining rings, each comprising five segments plus a key. Muck removal and segment supply were managed by rail-bound, battery-powered equipment to minimise the environmental impact.
The drive presented some of the most demanding ground conditions on the entire Phase-IV programme. The alignment runs through extremely hard rock, with uniaxial compressive strengths exceeding 200 MPa in places – conditions more typically associated with hard-rock mining than urban metro tunnelling.
TBM Narayani’s mixed-face cutterhead and hard-rock cutting tools were configured specifically for this challenging geology.
Once complete, the Aerocity–Tughlakabad corridor will improve connectivity across southern Delhi, linking the airport district with key residential and commercial centres and integrating with the wider Phase-IV network.
