The ₹30,000 crore underground artery reshaping Mumbai's transit landscape

Cultures · Published 3 October 2026 Swipe more like this →

In short: Mumbai's Aqua Line is more than just a new metro route; it is the city's first fully underground rail network. While designed to slash road congestion and carbon emissions, the massive engineering feat has faced intense legal battles over environmental impact and shifting ridership projections.

Spanning 33.5 km from Cuffe Parade to Aarey JVLR, the Aqua Line represents a monumental shift in Mumbai's infrastructure. The project, managed by the Mumbai Metro Rail Corporation Limited (MMRCL), features 27 stations, 26 of which are situated underground. A significant engineering highlight is the 170-metre twin-tunnel section that passes beneath the Mithi River, making it only the second under-river metro tunnel in India, following the Kolkata Metro Green Line.

The financial scale of the project is immense, with total costs estimated at ₹30,000 crore (US$3.1 billion). Funding was a complex global effort, including a substantial ₹13,235 crore soft loan from the Japan International Cooperation Agency (JICA) at an interest rate of 1.44%. Interestingly, the project's expansion was partially supported by Mumbai International Airport Limited (MIAL), which agreed to fund three airport stations, funded in part by a 'metro component' added to passenger fees.

However, the project's journey has been fraught with controversy. Environmental activists filed numerous petitions regarding the loss of over 5,000 trees, specifically targeting the car depot construction in Aarey. While the Supreme Court and Bombay High Court ultimately dismissed these challenges, the project remains a point of tension. Furthermore, while initial projections anticipated 1.5 million daily passengers, recent estimates suggest actual usage has reached only about 150,000 per day.

Despite these hurdles, the line has seen phased inaugurations, starting with the BKC to Aarey section on 5 October 2024, followed by further expansions through late 2025. The project also necessitated the rehabilitation of 2,807 families, particularly in the Girgaum-Kalbadevi area, to ensure safety during the intensive tunneling work.

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