- Sector: Urban rail
- Length: 223 km
- Investment: Rs 1,013 billion
- Ownership: Government (state)
- Implementing agency: Mumbai Metropolitan Region Development Authority, Mumbai Metro Rail Corporation Limited (Line 3)
- Mode of implementation: EPC
- Start date: 2016 (civil works commenced)
- Expected completion: 2021-26
The existing suburban rail system is under extreme pressure and the role of the bus system is limited to providing feeder services to suburban railways. There are constraints in expanding the road and rail network capacity. The Mumbai metro project has been undertaken to provide a rail-based mass transit facility to people residing in areas that are not connected by the existing suburban rail system. There are 14 upcoming lines at various stages of implementation. Most of the lines are under construction. The longest underground line, Line 3 Colaba-Bandra-SEEPZ, spans 33.5 km. As of August 2020, 85 per cent of tunnelling, with the help of 17 tunnel boring machines, and about 59 per cent of overall construction work have been completed.