Chennai Metro Phase-2: TBM ‘Eagle’ Achieves Breakthrough At Thirumayilai

1. TBM Eagle achieves breakthrough at Thirumayilai (UG-01 – Upline). CMRL has achieved a major milestone with the successful breakthrough of the upline tunnel boring machine (TBM) Eagle at the Thirumayilai shaft, marking the first TBM breakthrough under the UG-01 contract.

The underground section of corridor-4 from Light House Station to Kodambakkam flyover has been divided into two packages — UG-01 and UG-02, each comprising approximately 4 km of twin tunnels. To execute nearly 16 km of tunnelling in both directions, four TBMs with an excavated diameter of 6.67 metres have been deployed.

Tunnelling between Light House Station and Thirumayilai Station commenced in January 2024 using TBMs Eagle and Flamingo. TBM Eagle achieved its breakthrough on February 9, 2026.

The 1,981-metre-long tunnel, executed by Cemindia Projects Ltd, passes beneath several historic and sensitive structures, including Chennai Lighthouse, All India Radio, Russian Embassy, Dominic Savio School, Rosary Church and St. Raphael’s School. The alignment crosses 151 buildings, with overburden depths ranging from 4.5 metres to 23 metres.

The tunnel drive encountered challenging geological conditions, including rock strata and gas leakage, particularly near St. Raphael’s School. The TBM operated mainly in closed-face mode, with 17 cutterhead interventions, and the tunnel was completed over 24 months.

2. TBM Pelican commences tunnelling from Panagal Park to Boat Club (UG-02). CMRL has successfully launched TBM Pelican for the underground stretch from Panagal Park to Boat Club Station under corridor-4, UG-02. TBM Pelican has been launched from Panagal Park Station towards Boat Club Station for its final drive.

Another TBM, Peacock, launched earlier on the same stretch, has already completed 370 metres of tunnelling out of a total drive length of 1,898 metres.

TBM Pelican had earlier completed a 2-km tunnel drive from Panagal Park to Meenakshi College, safely passing beneath active Indian Railways tracks. Following this breakthrough, TBM Peacock was dismantled, transported back to Panagal Park, and reassembled for its new drive towards Boat Club Station, marking the second and final TBM launch in this section.

The upcoming drive involves complex engineering challenges, including tunnelling beneath the operational phase-1 Metro tunnels near Nandanam Metro Station, with depths reaching up to 30.2 metres below ground level.

Completion of the tunnel drive is targeted for December 2026.

The milestone events took place in the presence of T. Archunan, director (projects), CMRL; R. Ranganathan, general manager (construction), CMRL; C. Murugamoorthy, team leader, general consultants, along with officials from CMRL, AEON Consortium, and Cemindia Projects Ltd (formerly ITD Cementation India Limited).