The Delhi Metro Rail Corporation (DMRC) on Tuesday achieved a significant milestone in its Phase 4 expansion on the Golden Line, completing an underground tunnel between Chhatarpur Mandir and IGNOU Station on the Tughlakabad-Aerocity corridor.
“Tunnel Boring Machine (TBM) broke through at IGNOU Station after completing a 1,475-metre-long tunnel. The breakthrough was achieved using a 97-metre-long TBM, with two parallel circular tunnels being constructed for up and down movement,” the DMRC said in a statement.
Constructed at an average depth of approximately 26 metres, with a maximum depth of 36 metres and a minimum of 15 metres, the tunnel is among Delhi Metro’s deepest. It features 1,048 rings with an inner diameter of 5.8 metres, the statement said.
“This breakthrough marks another important step in our Phase 4 expansion, overcoming significant geological challenges to ensure seamless progress,” Anuj Dayal, Principal Executive Director, Corporate Communications, the DMRC said.
The tunnel was built using the Earth Pressure Balancing Method (EPBM), with precast concrete tunnel rings manufactured at a mechanised casting yard in Mundka.
The concrete segments were steam-cured to accelerate strength development, the DMRC said.
The tunnelling drive, which began on December 4, 2023, faced challenges due to a steep gradient and varied geological conditions, including mica and hard rock. These factors caused damage to the screw auger, which had to be replaced during the process, it added.
As part of the approved Phase 4 expansion, DMRC is constructing 40.109 kilometres of underground lines, with the Aerocity-Tughlakabad corridor accounting for 19.343 kilometres, the statement said.
