CHENNAI: Chennai Metro Rail Limited achieved twin milestones in the underground works of Corridor-4 of its Phase-2 project on Monday, with Tunnel Boring Machines Eagle and Pelican recording key breakthroughs on the stretch between Light House and Panagal Park, signalling steady progress on the 26.1-km corridor from Light House to Poonamallee Bypass.
Under the UG-01 package, TBM Eagle completed the first breakthrough at the Thirumayilai shaft on February 9. The 1,981-metre tunnel between Light House and Thirumayilai, executed by Cemindia Projects Limited, passed beneath several sensitive and heritage structures, including Chennai Lighthouse, All India Radio, the Russian Embassy, Dominic Savio School, Rosary Church and St Raphael’s School.
The alignment crossed below 151 buildings with overburden depths ranging from 4.5 metres to 23 metres. Engineers encountered challenging geological conditions, including rock strata and instances of gas leakage in parts of the stretch. The drive, which began in January 2024, was completed over 24 months, largely using closed-face mode with multiple cutterhead interventions.
In a parallel development under the UG-02 package, TBM Pelican was launched from Panagal Park towards Boat Club Station for its final drive, marking another breakthrough event on Corridor-4. The machine had earlier completed a 2-km drive towards Meenakshi College, safely passing beneath active Indian Railways tracks. Another TBM on the same section has already advanced 370 metres of the 1,898-metre drive.
The forthcoming stretch involves complex tunnelling beneath operational Phase-1 Metro tunnels near Nandanam, at depths of up to 30.2 metres. The underground works on this section are targeted for completion by December 2026.