India: Delhi Metro to become world’s largest single-city network by December 2025, surpassing New York

New Delhi: By December 2025, Delhi Metro will become the world’s largest metro network in a single city, surpassing the New York Metro’s 399-km record, Union Minister of Housing and Urban Affairs Manohar Lal announced on Thursday.

Speaking at a tunnel breakthrough event for the Golden Line at Vasant Kunj metro station, he said that with the addition of the 12-km Aerocity to Tughlakabad corridor, Delhi Metro’s operational length will exceed 400km, making it the longest single-city metro system globally.
Currently, Delhi Metro operates a 394-km network, which is set to expand significantly under Phase 4 of development. The minister also highlighted that metro rail networks are either operational or in progress across 29 states in India, with the total metro rail length now approaching 1,000km, making India the third-largest metro network in the world.

“Soon, India will have the world’s second-largest metro network, second only to China,” he added.
Major tunnel breakthrough
On February 25, Delhi Metro achieved a significant milestone in Phase 4 construction with the successful completion of an underground tunnel between Chhatarpur Mandir and IGNOU Station on the Tughlakabad-Aerocity corridor.

A Tunnel Boring Machine (TBM), a 97-meter-long engineering marvel, completed a 1,475-meter tunnel at an average depth of 26 meters, making it one of Delhi Metro’s deepest tunnels. The deepest metro tunnel in Delhi, on the Magenta Line at Hauz Khas, reaches 30 meters.

The tunnel was built using the Earth Pressure Balancing Method (EPBM) with pre-cast concrete tunnel rings manufactured at a dedicated casting yard in Mundka. Construction faced challenges due to steep gradients and varied geological conditions, including mica and hard rock formations, which required replacing the screw auger during excavation.
“All necessary safety measures were in place, with ground movement monitored using high-precision instruments to prevent structural settlements,” officials stated.

A step toward global leadership
Under Phase 4, Delhi Metro is constructing 40.1 km of underground metro lines, with 19.3 km dedicated to the Aerocity-Tughlakabad corridor.

Since its inception in 1998, Delhi Metro has consistently expanded its network, starting with its first operational section from Shahdara to Tis Hazari in December 2002. Phase 2 launched in 2006, Phase 3 in 2011, and Phase 4 in 2019. During Phase 3, over 30 Tunnel Boring Machines (TBMs) were deployed, constructing nearly 50 km of underground metro lines.
Delhi Metro’s expansion is a key component of India’s broader urban mobility strategy, reinforcing its position as a global leader in sustainable mass transit.