Even as phase I of Chennai Metro Rail marches ahead, plans are afoot to launch the 76-km phase II, which will be built entirely underground.

The project may take at least 10 years for completion.

The corridors for phase II, which include Madhavaram to Light House (17 km), Koyambedu to Injambakkam (27 km) and Madhavaram to Perumbakkam (32 km), will be built at a cost of Rs. 36,000 crore and they will cover most parts of the city, officials of Chennai Metro Rail Limited (CMRL) said.