Tunnel breakthrough achieved on metro line 7A; 22 km route to be readied in 2025

Mumbai's Metro Line 7A reached a milestone with a tunnel breakthrough, enhancing connectivity from Mira-Bhayander to the airport, 59% complete.

Mumbai: The Mumbai Metropolitan Region Development Authority (MMRDA) on Thursday marked a major milestone in the construction of Mumbai Metro Line 7A with a successful tunnel breakthrough between Andheri East and Chhatrapati Shivaji Maharaj International Airport (CSMIA). Chief minister Devendra Fadnavis officiated the event by activating the tunnel boring machine (TBM), in the presence of MMRDA Metropolitan Commissioner Dr Sanjay Mukherjee.

Mumbai, India - April 17, 2025: The first TBM tunnel breakthrough was achieved by the Mumbai Metropolitan Region Development Authority (MMRDA) for Metro Line 7A. This marks the successful completion of a 1.647-kilometer tunnel between Andheri (East) and Chhatrapati Shivaji Maharaj International Airport (CSMIA). The TBM, named "Disha," is the first underground tunnel constructed by MMRDA for its metro network in Mumbai, India, on Thursday, April 17, 2025. (Photo by Satish Bate/ Hindustan Times) (Hindustan Times)

Metro Line 7A is a 3.4-km extension of the operational Red Line 7 (Dahisar East to Gundavali). Of this, 2.5 km is underground and 0.94 km elevated. The extension will feature two stations — Airport Colony (elevated) and CSMIA Terminal 2 (underground) — and provide crucial interchanges with Metro Lines 1, 3, 6, and 9, offering seamless connectivity from Mira-Bhayander to the airport.

The tunnel breakthrough was achieved by TBM Disha, which completed the 1.647-km downline drive that began in September 2023. Starting at a depth of 30 metres, Disha navigated several engineering challenges, including tunnelling beneath Metro Line 3, under the Sahar Elevated Road ramp with just 1.5 metres of clearance, and around critical infrastructure such as water mains and sewer lines. “This tunnel boring machine overcame significant technical hurdles. It’s a key step toward delivering 150 km of metro lines within a year,” said CM Fadnavis. However, current progress suggests that by December 2025, only about 22 km is likely to be operational. This includes Metro 7A (Gundavali to CSMIA), Metro 2B (Mandale to Diamond Garden), and Metro 9 (Dahisar to Kashigaon).

Another breakthrough on the parallel upline tunnel is expected next month, further advancing MMRDA’s debut in underground metro construction. With the project now 59% complete, Metro Line 7A is anticipated to ease congestion around the airport and significantly enhance Mumbai’s east-west and north-south metro connectivity.