Mumbai's metro expansion is making significant strides as it crosses a pivotal milestone with the first tunnel breakthrough for Metro Line 7A. This ambitious corridor aims to connect South Mumbai to the extended northern suburbs and the upcoming Navi Mumbai International Airport, reflecting the city's evolving vision of creating a seamless and eco-conscious transit network.
As of April 19, 2025, 59 percent of construction for Metro Line 7A is already complete. The project includes an underground stretch that directly links to the city's international airport, touted as a turning point in building resilient and inclusive urban infrastructure. The new metro line will serve as a high-capacity link running from Colaba to Vasai-Virar via Mira-Bhayander, while also connecting to Thane and Navi Mumbai.
The corridor, which combines elevated and underground tracks, will feature two key stations—Airport Colony and CSMIA—designed to deliver smooth, time-efficient access to the airport for daily commuters and air travelers alike. Beyond improving connectivity, the metro line is positioned to relieve road congestion, lower vehicular emissions, and support the city's goals for a zero-net-carbon future.
The tunnel excavation for this ambitious project began on September 1, 2023, executed with the help of a Tunnel Boring Machine (TBM) under intensely challenging conditions. Engineers had to maneuver the machine through a tight urban landscape, passing above an active metro line and beneath critical roadways and utility networks. This achievement represents a textbook case in urban tunneling, showcasing meticulous planning and technological coordination under densely populated city constraints.
At a ceremonial event marking the breakthrough, senior officials acknowledged the engineering feat and reaffirmed their commitment to advancing 150 kilometers of metro coverage by the coming year. The broader Mumbai Metro blueprint envisions a 337-kilometer network designed to deliver equitable transit solutions and foster sustainable urban development.
Authorities overseeing the project highlighted that this progress is not merely about infrastructure but also about unlocking greater accessibility, convenience, and economic vitality. The tunnel completion reflects a drive to reimagine how people move through the city—not just faster but cleaner and smarter.
Meanwhile, in a related development, Reliance Jio subscribers traveling on the Colaba-Bandra-Aarey Metro Line 3 may not have mobile network access when it is fully operational. The reason for this potential inconvenience is that Jio has not joined the common infrastructure arrangement made by the Mumbai Metro Rail Corporation (MMRC) to provide mobile connectivity across the 33.5 km underground stretch.
Rival telecom service providers Bharti Airtel and Vodafone Idea have already signed on to deploy an In-Building Solution (IBS), ensuring their subscribers will have seamless network coverage inside Metro 3 tunnels and stations. To streamline operations and avoid duplication of cabling and radio equipment in the confined underground spaces, the MMRC mandated a shared IBS model.
Under this model, telecom service providers were to nominate a single IBS vendor to install and manage the mobile infrastructure, which all participating operators would then use. While Airtel and Vodafone Idea agreed to this consortium model and are moving forward with the implementation, Jio refused to participate, reportedly seeking to install its own parallel infrastructure—a proposal that MMRC did not accept due to space and safety constraints in the underground environment.
A senior MMRC official stated, "Jio was invited to join the unified infrastructure model, like other operators. But they insisted on deploying their own separate system, which is not technically or operationally feasible in a confined, underground space. The other telcos cooperated in the interest of passengers."
This development has sparked concern among commuters. Hemant Borade, a Jio subscriber, expressed his worries, saying, "I rely on Jio for UPI payments and work calls. If there's no signal in the Metro, it's going to be a huge inconvenience." Another Jio subscriber mentioned, "I chose Jio for better data speeds, but if I can't stay connected during my Metro ride, I might consider switching."
The IBS system, funded by participating telecom firms, is expected to be active from day one of Metro 3 operations. The MMRC has stated that Jio is welcome to join the arrangement provided it agrees to the common model.
As Mumbai contends with the mounting pressures of urbanization, infrastructure breakthroughs such as the Metro Line 7A tunneling work and the ongoing challenges with mobile connectivity reflect the need for integrated, future-ready mobility systems. The success of the tunneling work signals that sustainable and inclusive growth is achievable when ambition is matched with execution.
Ultimately, these developments strengthen hopes for a city that prioritizes both its people and the planet—one that is not only moving forward but doing so responsibly. The Mumbai Metro project, with its various components, aims to bridge economic hubs and residential belts across the metropolitan region, while also ensuring that the urban transit landscape aligns with global benchmarks of efficiency and climate resilience.
