Chennai Metro Phase II: Deepest Underground Line to Connect Panagal Park and Boat Club via Nandanam
In the second phase of the Chennai Metro Rail project, a new underground line will be constructed from Panagal Park to Boat Club via Nandanam - the first in the city to be built beneath an existing operational metro tunnel. The 1.9 km stretch will be laid under the Nandanam Metro station, which is already functioning under Phase I, without affecting train services.
Currently, metro trains operate from Wimco Nagar to Chennai Airport via Nandanam under Phase I, while the new Phase II corridor will connect Poonamallee to Lighthouse, also passing through Nandanam, making it the only area with two operational metro lines.
The new tunnel will run at a depth of 29.8 meters - nearly twice the depth of the existing tunnel, which lies at 16.5 meters. The Chennai Metro Rail Limited (CMRL) has obtained permission from the Commissioner of Railway Safety to proceed with the work, expected to begin in the first week of December.
The Tunnel Boring Machine has already been lowered at Panagal Park and will begin operations in about three weeks. Officials said advanced robotic monitoring systems will continuously track structural stability to ensure safety, similar to the process followed during tunneling under Kodambakkam railway station.
According to engineers, the machine will encounter clay-rich soil along most of the route and broken clay rocks beneath Nandanam. Despite the deep tunneling, CMRL officials confirmed that ongoing train operations will remain unaffected. The new line is expected to significantly enhance Chennai’s metro network and ease connectivity across key city zones.
