Underground tunnel at Pulbangash metro station complete: DMRC

While this completed tunnel is the downline section of the corridor, DMRC said the up-tunnel is in progress.

The Delhi Metro Rail Corporation (DMRC) has finished constructing an underground tunnel at the Pulbangash metro station on Red Line, as part of the Janakpuri West - RK Ashram Marg extension of the Magenta line, officials said on Sunday.

DMRC is constructing nearly 103km of new metro lines across six corridors (Photo for representation)

The tunnel has been built between the Pulbangash on Red line and the upcoming Sadar Bazaar station on the Magenta line.

DMRC officials said the work on the tunnel included extensive ground strengthening around the existing pier. “The Tunnel Boring Machine (TBM) had to carefully navigate and create the tunnel below the elevated viaducts on which trains of the Red line were operational. The Red line viaduct here stands on open foundations with a balanced cantilever span and so tunnelling beneath such a structure required extraordinary engineering precautions to ensure its safety,” Anuj Dayal, principal executive director, corporate communications at DMRC, said.

“A detailed strategy was adopted to strengthen the area around the pier of the Red line. A grouting programme called TAM (Tube-a-Manchette) was implemented. As per this technology, 180 TAM boreholes were arranged around the pier. After that, high-strength cement grouting was done to stabilise the soil, fill the voids and in the process, increase the load-bearing capacity,” Dayal said.

While this completed tunnel is the downline section of the corridor, DMRC said the up-tunnel is in progress.

As part of its Phase 4 expansion, DMRC is constructing nearly 103km of new metro lines across six corridors. Currently, three corridors—Janakpuri West to RK Ashram Marg (Magenta line extension), Majlis Park to Maujpur (Pink line extension), and Aerocity to Tughlakabad (new Golden line) — are already under construction and nearing completion. Besides, the Pink line is expected to start operations this year and the remaining two corridors are scheduled to be completed by mid-2026.