By rosebell
In order to constructing around 16 km of twin tunnels on the Panagal Park–Boat Club stretch of Corridor 4, four TBMs with an excavated diameter of 6.67m has been launched, whereas Chennai Metro Rail Limited (CMRL) has commissioned a tunnel boring machine (TBM) for Phase 2 that comprises three corridors covering 118.9 km with 128 stations, marking a fresh phase of underground work beneath the city’s Phase 2 expansion.
With 26.1 km length, the Corridor 4 stretches from Light House to Poonamallee Bypass and features a key underground portion between Light House at Marina Beach and Kodambakkam Flyover, split into two packages, UG-01 and UG-02.
On 12 December 2025 the latest launch, for package UG-02, took place for the drive between Panagal Park and Boat Club.
Completing a 2 km drive from Panagal Park to the Kodambakkam ramp retrieval shaft near Meenakshi College on Arcot Road, the TBM Peacock delivered the first breakthrough on the underground stretch of Corridor 4 on 23 July 2025.
That drive involved tunneling below live Indian Railways tracks.
With the aim of reassembling it for a second drive of 1.89 km towards Boat Club Station,the machine was dismantled at Kodambakkam, taken back to Panagal Park after the breakthrough.
As the first TBM to commence work on one of the twin tunnels in this section, the current drive includes tunneling beneath operational Phase 1 metro tunnels near Nandanam Metro Station, with the alignment reaching depths of up to 30.2m below ground.
While the location of starting up the TBM Peacock was the down line of Corridor 4, it is due to move from Panagal Park towards Nandanam and on to the retrieval shaft at Boat Club Station.
The scheduled date for completing this drive by CMRL is November 2026.
