STN: The Chennai Metro Phase 2 project recorded a rare milestone. For the first time in India, a tunnel boring machine (TBM) breakthrough and a TBM launch took place at the same station. This happened at Kolathur Metro Station. The activity comes under Package UG-06 of Corridor 5.
Corridor 5 of Chennai Metro Phase 2 runs for 47 km. It connects Madhavaram to Sholinganallur. The twin activities at Kolathur mark steady progress in the underground construction works along this route.
Project Team Present at the Event – Chennai Metro Phase 2
Senior officials from Chennai Metro Rail Limited (CMRL), Tata Projects Ltd., and the General Consultant teams were present at the site.
Those present included T. Archunan, Director (Projects), and T. Livingstone Eliazer, Chief General Manager (PP&D). Other members included Karthikeyan M, Joint General Manager. From Tata Projects Ltd., officials present were K. Ramesh, Project Director, and Natthapong Katkaew, Project Manager. Representatives of the General Consultant team, including Tony Burchell, Team Leader, and Udayakumar A, Chief Resident Engineer, also joined the event. Teams from all organisations coordinated during the TBM activities.
TBM Breakthrough at Kolathur – Chennai Metro Phase 2
TBM S97, named “Mullai,” achieved the breakthrough. The machine travelled from the Kolathur Ramp and reached Kolathur Station. The TBM drive began on 23 May 2025. It completed 246 metres of tunnelling.
The team faced major engineering challenges. Overburden was very low at only 1.8 metres. The tunnel had a steep gradient of -3.8%. The site also needed heavy ground support. This was because the area has constant road traffic and limited working space. Despite these issues, the TBM reached the station safely.
TBM Launch Towards Srinivasa Nagar
At the same station, a second TBM was launched. TBM S120, named “Kurinji,” began its drive from Kolathur towards Srinivasa Nagar. The planned tunnel length is 1060 metres.
This stretch passes through Grade-4 and Grade-5 rock layers. The alignment also includes a 230-metre curved section. These conditions will require slow and controlled excavation. The launch marks the start of another key underground link between the two stations.
Why This Milestone Matters
Two major TBM operations at a single station on the same day are rare. It shows strong coordination between teams and efficient planning. It also highlights the pace of underground works under Corridor 5. As more breakthroughs and launches follow, the network will move closer to completion.
The progress at Kolathur fits into the broader goals of Chennai Metro Phase 2, which aims to expand connectivity across the city and reduce road congestion.
FAQs
A: Chennai Metro Phase 2 covers about 118 km across three corridors: Corridor 3, Corridor 4, and Corridor 5.
A: CMRL is deploying more than 20 TBMs for various underground packages across the three corridors.
A: Package UG-06 covers underground tunnelling and station construction between Kolathur and Villivakkam areas. It includes ramp structures, tunnels, and station works.
A: CMRL has targeted completion in phases between 2027 and 2028, depending on construction fronts.
A: Low overburden means the soil cover above the tunnel is shallow. This increases the risk of ground settlement and requires extra support measures.
A: Earth Pressure Balance (EPB) TBMs are used for most underground packages in Phase 2 due to mixed ground conditions in Chennai.
A: Yes. Corridor 5 will interchange with Corridors 3 and 4 at multiple stations, improving network connectivity.
