Mumbai’s push towards an integrated, sustainable, and congestion-free public transport system reached a defining moment as the Mumbai Metropolitan Region Development Authority (MMRDA) completed its first underground metro tunnel breakthrough on Metro Line 7A.
The tunnel boring machine (TBM), deployed to create the subterranean section linking Andheri East to Chhatrapati Shivaji Maharaj International Airport (CSMIA) Terminal 2, achieved a breakthrough near Vile Parle. This milestone marks the first time MMRDA has led such an underground initiative within Mumbai, indicating a new phase in the city’s transport infrastructure evolution. The 3.4-kilometre-long Metro Line 7A is a critical connector in the Western Suburbs’ growing metro ecosystem. With 2.5 kilometres of the alignment underground and 0.94 kilometres elevated, the project not only improves east-west rail connectivity but also serves as a key corridor linking to the international airport. TBM operations for this route commenced with the machine being lowered 30 metres underground in September 2023. Since then, it has carved through challenging geological conditions, including sharp gradients and major underground utilities such as sewage and water pipelines. Officials confirmed that the tunnel spans a diameter of 6.35 metres and features specially designed precast concrete rings for structural stability across six identified zones.
This infrastructural feat was not just a technical challenge but a symbolic leap toward climate-conscious mobility. As urban congestion continues to plague the city, sustainable metro projects like Line 7A present a viable alternative to carbon-emitting surface transport. The line is projected to seamlessly integrate with existing corridors such as Metro Line 2A, Line 7, and the upcoming Line 9, facilitating uninterrupted travel from Mira-Bhayandar and Vasai-Virar to CSMIA. Further, the broader plan also envisages connections to the Navi Mumbai International Airport (NMIA), potentially transforming airport commutes across the metropolitan region.
A statement from the Chief Minister’s office highlighted the technical complexity of the breakthrough and reaffirmed the government’s commitment to completing metro infrastructure that will bring long-term value to commuters. As the machine crossed under existing elevated Metro Line 3 structures and sensitive utility networks, the engineering prowess displayed in navigating densely layered urban topographies drew commendation. The breakthrough was witnessed by the Chief Minister himself, who inspected the tunnelling site and reviewed the progress in real time.
Nearly 59 percent of construction work for Metro Line 7A has already been completed, according to MMRDA updates. The authorities are optimistic that the pace of the remaining execution will accelerate with the breakthrough, setting the stage for operational readiness in the coming phases. Beyond its mobility benefits, the project underscores the state’s broader ambition to build equitable and eco-sensitive urban infrastructure. By offering a cleaner, faster, and more accessible transport option, Metro Line 7A contributes to Mumbai’s vision of becoming a net-zero emission city with a people-first mobility framework.
While the city continues to grapple with traffic bottlenecks, air pollution, and strained public infrastructure, projects like this offer a path forward—bridging geographic divides, reducing commute times, and building resilience against the environmental cost of unplanned urban expansion. With the successful completion of this tunnelling milestone, Mumbai takes another firm step towards reshaping its mobility narrative.
Underground Metro Tunnel Completed in Mumbai