STN: Chennai Metro Rail Limited (CMRL) has completed another key step under Chennai Metro Phase 2. The second Tunnel Boring Machine (TBM) under the UG-01 contract has achieved a breakthrough at the Thirumayilai shaft on Corridor 4.
The downline TBM, named Flamingo S-1352A, completed its tunnel drive on 27 February. It covered a distance of 1,985 metres between Light House and Thirumayilai. Earlier, the upline TBM, Eagle S-1073B, completed its breakthrough on 9 February. With this, both parallel tunnels on this section now stand completed.
This marks steady progress for Chennai Metro Phase 2, which aims to expand the city’s metro network.
Chennai Metro Phase 2 Corridor 4: Engineering Challenges Underground
The tunnelling work was carried out by Cemindia Projects Limited. The team worked beneath some of the most sensitive and crowded parts of the city.
The tunnel alignment passed under:
- The Lighthouse area
- The All India Radio campus
- The Russian Embassy zone
- Rosary Church
- The MRTS bridge
- Buckingham Canal
The route also ran below other important and older structures. Engineers had to ensure that surface buildings remained safe during the tunnelling process.
The work was not easy. The team faced rocky ground conditions. In some areas, the soil cover above the tunnel was shallow. In other sections, the overburden was deeper due to a stacked tunnel design. Workers also encountered unexpected gas pockets during excavation.
One of the most complex parts of the drive was beneath Kutcheri Road. Here, engineers executed a stacked tunnel “drive-through.” This required careful planning and constant monitoring.
At Thirumayilai, the tunnel reaches a depth of around 28 metres. This makes it the deepest underground station in Chennai Metro Phase 2.
Importance of Thirumayilai in Chennai Metro Phase 2
Thirumayilai station holds strategic value in the new network. It will serve as an interchange point where Corridor 4 connects with Corridor 3.
This interchange will help passengers switch lines easily. It will reduce travel time across the city. It will also improve connectivity between different parts of Chennai.
With both TBMs—Eagle and Flamingo—now completing their drives under the UG-01 package, the underground construction risk for this stretch has reduced. The twin tunnel completion allows the project team to move ahead with the next phase of construction work.
Mrs. Mamta Shah, MD & CEO, Urban Infra Group, commented on the milestone. She said that executing deep and stacked tunnelling beneath heritage and high-security zones requires careful planning and strong technical skills. She added that the successful completion of both tunnel drives between Light House and Thirumayilai reflects the team’s capability and coordination.
The progress on Corridor 4 shows that Chennai Metro Phase 2 is moving forward as planned. The expansion will strengthen public transport in the city. It will also support better integration with other modes of transport.
As work continues across different corridors, each breakthrough brings Chennai closer to a larger and more connected metro system.
FAQs
A: Chennai Metro Phase 2 spans around 118.9 kilometres across three corridors.
A: The project includes Corridor 3, Corridor 4, and Corridor 5.
A: The project is being executed in stages. Full completion is expected in phases over the next few years, depending on construction progress.
A: A TBM is a large machine used to excavate tunnels underground. It cuts through soil and rock while supporting the tunnel walls.
A: Corridor 4 will improve connectivity between key residential and commercial areas. It will reduce traffic congestion and provide a faster travel option.
