Chennai Metro Rail (CMRL) has marked a major milestone in the Phase-2 project with the breakthrough of tunnel boring machine (TBM) ‘Eagle’ at Thirumayilai station, on Corridor-4.

This underground section, spanning from Light House to Kodambakkam Flyover, involves nearly four km of twin tunnels. Tunneling began in January 2024, and TBM Eagle achieved its breakthrough on 09 February, 2026. The 1,981-mtrs.-long tunnel, executed by Cemindia Project, passes under historical sites like Lighthouse, All India Radio, and Russian Embassy, facing challenging geological conditions, including rock strata and gas leakage. TBM Eagle worked in closed-face mode, with 17 cutterhead interventions, to complete the tunnel.

In addition, TBM Pelican has commenced tunneling from Panagal Park to Boat Club, with another TBM, Peacock, completing 370 mtrs. of tunneling. These developments bring the Phase-2 expansion closer to its completion, with a total of 128 stations planned, covering 118.9 km.