Tunnel stretch
The downline tunnel between Pulbangash and Sadar Bazaar covers a total length of 800 m, forming a key section of the Janakpuri West–RK Ashram Marg corridor.
Project timeline
Excavation began in mid-October 2025, and the tunnel is expected to be completed in around five months, keeping the Phase-IV schedule on track.
Tunnel depths
The tunnel boring machine operates at depths ranging from 13 m to 18 m below the surface, navigating through challenging underground conditions.
TBM specifications
The machine has an internal diameter of 5.8 m and is specially designed to handle complex urban tunnelling.
Current progress
So far, approximately 140 m of the tunnel has been excavated, marking steady advancement toward completion.
Engineering feat
The TBM has successfully passed beneath the Red Line viaduct and the busy Rani Jhansi flyover without affecting existing traffic.
Railway crossing
The machine is now tunnelling under five active railway tracks near Sabzi Mandi, with train operations continuing safely above.
Safety oversight
DMRC and Indian Railways are closely monitoring the tunnelling work to ensure both operational and structural safety throughout the project.
Muck train operations
Battery-powered ‘muck trains’ transport precast tunnel segments and remove excavated earth, running along specially laid tracks inside the tunnel.
Excavation system
The TBM’s cutter head is connected to a conveyor system that feeds excavated material directly to the muck trains, ensuring smooth and efficient tunnel construction.