Lighthouse-Thirumayilai Metro Tunnel to Reach Completion by September After Overcoming Major Setbacks

The Tunnel Boring Machine, ‘Flamingo’, on Chennai Metro to Reach Thirumayilai by September Despite Major HurdlesAfter overcoming a series of engineering and traveling through inhospitable environments for most of her life, Chennai Metro Rail’s major second phase project is now getting close to a very significant point in construction – with the tunnel boring machine (‘Flamingo’) expected to be gone from Light House station to Thirumayilai by September 2025. This is once more another development that followed on from previous periods when a quarter-century span appeared encouraging or at least promising for the continuation of such work MEP feels. And so this June has seen more than its share of understanding and defeating problems.

Flamingo, which began tunneling in September 2023 from Light House—the longest station in Phase II—forms part of Corridor 4, which spans 26.1 km from Light House to Poonamallee. The underground portion from Light House to Kodambakkam via Thirumayilai and T. Nagar stretches about 10 km and is a key segment of the 18.9 km network planned under Phase II.

The twin tunnels along this stretch are being dug by TBMs Flamingo and Eagle. While Flamingo is currently advancing through Kutchery Road station, Eagle is preparing to enter the same. So far, Flamingo has bored 1.3 km and Eagle has completed 1.2 km.

The road, however, has been far from smooth. Engineers ran into significant challenges in the early going, including the release of methane and carbon monoxide shortly after tunneling started, prompting a temporary halt. The machine also encountered highly abrasive soil, damaging critical components like the cutter discs and knives, and requiring repeated replacements.

In one of the most complex setbacks, the cutter head of Flamingo suffered a major issue that halted work for nearly 40 days. A cavity had to be created inside the tunnel for engineers to manually access and repair the machine a delicate and risky operation that was completed successfully.

Once operational, the tunnel will support Chennai’s first set of driverless trains, offering seamless travel between major hubs like Thirumayilai, Kutchery Road, and Marina Beach.

With Flamingo expected to reach Thirumayilai by September, this segment of Chennai Metro’s Phase II is on track despite the rocky path, quite literally, beneath the city’s surface.