"Substantial work has been done in the last couple of months with an expenditure of Rs 1,281 crore till November. Nearly 17 per cent work of the project work has been completed till now," Chahal said.
About 175 acres of land has so far been reclaimed from the Arabian Sea for the project and another 102 acres is being reclaimed, the civic chief said.
A 400-metre-long tunnel boring machine of 39.6 feet diameter, which is the largest in India now, has been fully assembled on the reclaimed land and tunnel boring will commence from January 7, 2021, he said.
The boring machine, named Mavala, is going to build twin tunnels of 1,920 metre length between Marine Lines and Priyadarshini Park in south Mumbai.