New Delhi: Delhi Metro is set to become the world’s longest metro network in a single city by December 2025, surpassing New York Metro’s 399 km record, announced Manohar Lal, the Minister of Housing and Urban Affairs. With the opening of the 12-km Aerocity to Tughlakabad stretch (Golden Line), Delhi Metro’s total length will exceed that of New York’s. Currently, the network is 394 km long.
The minister highlighted that metro projects are operational or underway across 29 states in India, and the total metro network in the country is about 1,000 km, making it the third-largest globally. India is expected to soon have the second-largest metro network, after China.
On February 25, Delhi Metro achieved a significant milestone in Phase 4 with the completion of an underground tunnel between Chhatarpur Mandir and IGNOU Station on the Tughlakabad-Aerocity corridor. The breakthrough was made with a 97-meter-long Tunnel Boring Machine (TBM), which excavated a 1,475-meter-long tunnel. The tunnel was constructed at a depth of about 26 meters and is one of the deepest in Delhi Metro, with the Hauz Khas section of the Magenta Line reaching 30 meters. A total of 1,048 concrete rings were installed in the tunnel.
The tunneling process began on December 4, 2023, and faced challenges such as steep gradients and varying geology, which caused a screw auger to break and required replacement. The construction was carried out with strict safety measures, and ground movements were monitored to prevent any structural damage. The Phase 4 project includes 40.109 km of underground tunnels, with 19.343 km of the Aerocity-Tughlakabad section being underground.
Since the launch of Delhi Metro in 1998, TBMs have been used for tunnel construction, starting with Phase 1. By Phase 3, about 30 TBMs had been deployed, and these machines continue to play a critical role in urban tunneling projects.