Chennai Metro Phase-II TBM hat-trick: Kaveri, Marutham and Adyar break through in three days
CMRL recorded three Phase-II TBM breakthroughs from September 29 to October 1, including a 915-metre Adyar drive completed beneath a busy urban corridor.
Chennai Metro Phase-II recorded three tunnel boring machine breakthroughs in three consecutive days, marking one of the project’s most concentrated recent construction milestones. CMRL’s October 1 release lists breakthroughs by Kaveri, Marutham and Adyar between September 29 and October 1, 2026.
Three breakthroughs, three dates
On September 29, Corridor 3 downline TBM Kaveri achieved a breakthrough at Kilpauk Medical College station. On September 30, Corridor 5 downline TBM Marutham broke through at Villivakkam Bus Terminus station. On October 1, Corridor 3 downline TBM Adyar reached RK Salai station.
The milestones involve different packages and locations, so the word “hat-trick” describes the timing of the achievements rather than one continuous tunnel drive.
Adyar’s 915-metre drive
TBM Adyar completed a 915-metre downline tunnel drive between Royapettah and RK Salai in 277 days. The machine worked below an urban area with an overburden of roughly 9 to 13 metres and passed near structures including Peters Bridge, the EPFO building, Andhra School and shop lots.
CMRL says 11 cutterhead interventions were carried out during the drive and that the tunnel was completed without major ground settlement or adverse impact on existing infrastructure. The milestone is significant because underground work in a dense city requires coordination between tunnelling, traffic, utilities, buildings and station construction.
Marutham’s railway-track crossing
Marutham’s drive towards Villivakkam Bus Terminus covered 601 metres and passed below five railway tracks at Villivakkam Railway Station. CMRL says the breakthrough was completed without disruption to the public or ongoing traffic. Corridor 5 includes a 5.01-km underground section and a twin-tunnel length of 3.94 km in the package described by the operator.
What the milestone does not mean
A TBM breakthrough completes one construction drive; it does not mean that the whole corridor is ready for passenger service. Trackwork, station fit-out, power, signalling, testing and safety certification still determine when a new section can open.
CMRL’s official press release dated October 1, 2026 is the source for the dates, machine names and engineering details in this report.
