Subterranean Chess: How Mumbai’s Metro 7A Navigated a Water Crisis

Building a metro in Mumbai is a lot like performing surgery on a patient who is still running a marathon. Every time you dig, you are likely to hit a nerve or a vein that the city cannot live without. This week, engineers working on the Metro 7A airport link finally figured out how to bypass one of those vital organs: a massive 2,400 mm water trunk main that had been threatening to stall the project indefinitely.

The problem was simple but terrifying for the planners. Directly in the path of the new line sat the Upper Vaitarana pipeline, a high-capacity artery that serves a huge portion of the city. In most cities, you might just move the pipe, but in Mumbai, that was not an option for the longest time. The risk of cutting off water to thousands of homes or accidentally causing a catastrophic burst was too high. For a while, the project sat at a standstill while the team debated their next move.

Instead of a simple relocation, the engineers successfully executed a sophisticated diversion. By working in a tightly controlled shutdown window and coordinating with multiple departments including the Hydraulic Engineer’s Office and the K/East Ward, the team managed to realign the massive line without the city losing its cool. They essentially threaded the needle, ensuring the new transit structures could be built without putting a gram of stress on the water supply.

This is a huge win for the 3.4 km stretch. Line 7A is the piece of the puzzle that will finally connect the city’s north-south corridors directly into the international airport. For anyone who has ever been stuck in a two-hour crawl on the Western Express Highway just to catch a flight, this progress is personal. It represents a future where you can hop on a train in the suburbs and step out right at Terminal 2. Underground Progress and the Road AheadThe utility diversion marks a significant milestone for Metro Line 7A, which achieved a technical peak with its tunneling drives. Tunnelling was carried out using two massive machines: TBM Disha and TBM Dhruv. While Disha led the charge on the downline, completing its breakthrough in April 2025, Dhruv handled the 1.65 km upline tunnel. These machines dived deep beneath the Sahar Elevated Road, navigating a complex web of existing infrastructure including the operational Metro Line 3.

Metro Line 7A is a critical extension of the operational Red Line (Metro Line 7), which currently runs from Andheri (East) to Dahisar (East). The corridor will feature two distinct stops: an elevated station at Airport Colony and a deep underground station at Chhatrapati Shivaji Maharaj International Airport. The latter is being built parallel to the Metro Line 3 airport station, creating a massive transit hub beneath the terminal.

This project is just one thread in the MMRDA’s larger tapestry, a planned 337 km metro network designed to shrink the city. With Metro Lines 1, 2A, and 7 already humming with daily commuters, and the fully underground Line 3 (Aqua Line) now partially operational, the addition of Line 7A is about more than just mileage. It is about closing the gaps in a system that aims to move millions of people once the entire network is complete.

While the authorities are being careful not to promise a specific opening day just yet, clearing this water pipe hurdle means the hardest part of the hide-and-seek with Mumbai’s underground utilities is likely over. It is a classic Mumbai story, the city is so crowded that the only way to build the future is to respectfully dance around the infrastructure of the past.