Chennai Metro Rail (CMRL) has achieved a significant milestone in its Phase-II expansion by completing the city’s longest twin tunnel stretch between Panagal Park and Kodambakkam ramp.

The 2.08-km tunnel drive was completed after tunnel boring machine (TBM) ‘Pelican’ achieved its final breakthrough on 15 October, 2025. This follows an earlier breakthrough by TBM ‘Peacock’ on July 23, marking the completion of both up and down tunnels for Corridor-4, Package UG-2. Commencing on 01 March, 2024, the tunnelling took 594 days and reached a depth of 31.4 mtrs., navigating complex urban and geological challenges such as fractured strata, high-density buildings, and vital transport infrastructure, including Indian Railways tracks and two active flyovers.

The alignment included a tight S-curve with a 206-mtrs, radius and the steepest gradient of +2.581 percent in the project. Additionally, CMRL’s Nandanam headquarters has been awarded the IGBC Platinum certification for its sustainable practices, reaffirming the agency’s commitment to green infrastructure.