The tunnelling work for the Phase-3 Metro project has been finished as a 1.25-km tunnel between Vasant Vihar and Munirka on the Janakpuri West-Botanical Garden section, to be known as Magenta line, has been completed, the Delhi Metro said on Tuesday. The work on this tunnel about 20 metres below surface started in October 2015 and ended on Monday evening.

“The Delhi Metro Rail Corporation (DMRC) completed one of the largest tunneling projects in any urban area across the world in this phase, where a record 30 tunnel boring machines (TBM) were used to bore nearly 80-km long underground tunnels (taking into account tunnels for to and fro movement of trains),” the DMRC statement said.

The total underground corridor length in Phase 3, including stations, is about 54 km, which includes Janakpuri West-Botanical Garden (Magenta line) and Majlis Park-Shiv Vihar (Pink line), among others.  Of the 38-km Janakpuri West-Botanical Garden corridor, about 23 km is underground. “At Hauz Khas, the new tunnel passed below the already operational tunnel of Delhi Metro’s Yellow line,” the statement said.

“A 1.4-km tunnel between Shankar Vihar and Vasant Vihar on this section was fraught with challenges as it passed below the rocky Aravali ranges and special rock TBMs were pressed into service,” it added.  Of the 59-km Majlis Park-Shiv Vihar corridor, about 19 km is underground. Tunneling was done below the elevated metro lines at Azadpur (Yellow line), Netaji Subhash Place (Red line )and lajpat Nagar (Violet line), including passing below another tunnel at the INA station on the Yellow line