The entire tunnelling work of phase-III of expansions is expected to be finished by the end of the year.

With 19 Tunnel Boring Machines (TBMs) simultaneously being engaged in constructing Metro tunnels, Delhi Metro officials say the Capital has emerged as one of the cities with the largest tunnelling project ever undertaken below any major urban centre globally.

The entire tunnelling work of phase-III of expansions is expected to be finished by the end of the year. “The use of 19 TBMs simultaneously within the confines of one city is probably among the highest used anywhere in the world. In phase-II , the Delhi Metro had used a total of 14 TBMs during the entire span of work,” said a DMRC spokesperson.

Over 53 kilometres of underground Metro lines is being constructed under phase-III, comprising 74 different tunnelling drives of about 37 kilometres. “Approximately, 35 TBMs are to be used for this mammoth assignment during the entire third phase and about 21 kilometres of tunnels (or 41 km of tunnels including up and down tunnels) and 33 tunnelling drives have already been completed so far,” the spokesperson said.

The tunnelling drives of the Metro have since passed under railway tracks, flyovers, existing Metro viaducts, and Metro tunnels. The tunnels have passed below railway tracks (at Palam, ITO), flyovers (Munirka, Hauz Khas, Palam), Metro viaducts (Kalkaji, Janakpuri West, Lajpat Nagar), and Metro tunnels (IGI Airport), and their construction did not cause any disruption to the flow of traffic on the flyovers or movement of trains on the railway tracks above.

Officials said that for the current phase, many TBMs are being used because of the quantum of underground construction, which has increased significantly in comparison to the last two phases. “The use of so many TBMs has ensured that the Delhi Metro has been able to carry out construction work through many congested as well as traffic-heavy areas such as Old Delhi, Ring Road, and Outer Ring Road without any major diversion of the roads or demolition of buildings,” said the spokesperson.