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Chennai Metro Rail Limited (CMRL) has achieved an important construction milestone in Phase 2 of its metro expansion. The Tunnel Boring Machine (TBM) named "Eagle" has completed its breakthrough at the Thirumayilai shaft on Corridor-4. This is the first TBM breakthrough under the UG-01 underground contract, marking a major milestone for the project.
Chennai Metro Phase 2
Phase-2 of the Chennai Metro is a large expansion covering 118.9 km across three corridors and will add 128 new stations to the existing metro network. Among these, Corridor-4, which runs for 26.1 km from Light House to Poonamallee Bypass, has shown fast progress, especially in its underground sections.
Underground Stretch
The underground stretch between Light House and Kodambakkam Flyover has been divided into two packages, UG-01 and UG-02. Each package includes nearly 4 km of twin tunnels. To carry out the work, four TBMs have been deployed. Each machine has a tunnel diameter of 6.67 metres, and together they will bore about 16 km of tunnels.
Tunnelling Work
Cemindia Projects Limited executes UG-01 tunnelling work, and the tunnel alignment passes beneath several well-known locations in the city, including the Chennai Lighthouse, All India Radio, the Russian Embassy, Rosary Church, and St Raphael's School. Engineers had to handle difficult ground conditions, including rocky layers and gas leaks, while working at depths between 4.5 metres and 23 metres below ground.
Tunnelling for Metro Phase 1
Under the UG-02 package, another TBM called "Pelican" has been launched from Panagal Park and is moving towards Boat Club Station for its final stretch. TBM "Peacock" has already completed 370 metres of its total 1,898-metre drive. This section is even more challenging, as tunnelling is being done below operational Phase-1 metro lines near Nandanam at depths of over 30 metres. The underground work on this stretch is expected to be completed by December 2026.
