19 tunnel boring machines deployed for Metro's Ph-3 expansion

Giving a major push to its Phase-III expansion, Delhi Metro has deployed as many as 19 Tunnel Boring Machines (TBM) which are working simultaneously below several critical junctions of the national capital.
Apart from engaging the TBMs, Delhi Metro Rail Corporation (DMRC) has also initiated a total of 33 tunnelling drives across the city in places around Hauz Khas, IIT, Lajpat Nagar, Kalkaji and also beneath Old Delhi areas.
According to officials, the task has been challenging as such a massive tunnelling activity involves risks especially when the construction is undertaken below congested localities or below railway tracks, flyovers, existing metro viaducts or tunnels.

The tunnelling drives have so far passed below railway tracks (at Palam, ITO), flyovers (at Munirka, Hauz Khas, Palam), metro viaducts (at Kalkaji, Janakpuri West, Lajpat Nagar) and tunnels (at IGI Airport).
Incidentally, two TBMs have been deployed under Delhi Gate and Red Fort areas in the walled city for the upcoming Central Secretariat-Kashmere Gate heritage corridor.
"Before every tunnelling drive, detailed soil quality, building condition surveys are done and corrective measures taken if needed.
"In addition, the progress of the TBMs are very closely monitored and custom made instrumentation is done above the TBM routes to monitor any movement in the earth's surface or the condition of the structures above," an official said.