In a major engineering milestone for Mumbai’s metro infrastructure, the Tunnel Boring Machine (TBM) deployed on Metro Line 7A has successfully completed its 1.6-kilometre underground journey between Andheri East and Chhatrapati Shivaji Maharaj International Airport (CSMIA). The breakthrough was achieved on 17 April, marking a significant leap forward in the city’s push for enhanced urban mobility.
Developed by the Mumbai Metropolitan Region Development Authority (MMRDA), Metro Line 7A is the agency’s first foray into underground metro construction, and part of a larger strategy to seamlessly connect Mumbai’s transport hubs.
Launched in September 2023, the TBM tunnelled at a depth of 30 metres through one of the city’s most congested zones. The route, fraught with complex challenges, passed under the Sahar elevated road, the Metro Line 3 corridor, and several critical underground utilities. In some sections, clearances dropped to as little as 1.5 metres, necessitating precise navigation using cutting-edge tunnelling technology.
The tunnel itself boasts a final diameter of 6.4 metres, and was constructed using advanced precision-guided systems designed to safeguard surrounding infrastructure, even under live traffic conditions.
Describing the project as a game-changer, Maharashtra Chief Minister Devendra Fadnavis, during a site review at Vile Parle, remarked: “The CSMT to airport connection has now become a reality. This is truly an engineering marvel, where the elevated and underground Metro lines converge.”
Deputy Chief Minister Eknath Shinde echoed similar sentiments, calling it a “proud moment” for Mumbai and praising the seamless link between the city centre and international airport.
MMRDA Commissioner Sanjay Mukherjee added that connectivity to the airport is a vital step for Mumbai’s long-term development, stating: “While this network is being interconnected internally, connecting it to the international airport is a necessity for the city.”
Spanning 3.4 kilometres, Metro Line 7A is an extension of the operational Line 7 that runs from Dahisar East to Gundavli. Of the total length, 2.5 kilometres will be underground, with the remaining section elevated.
The extension will feature two new stations: an elevated station at Airport Colony, and an underground terminal at CSMIA. Once completed, the line will offer direct airport access for commuters from both the northern suburbs (Mira-Bhayandar, Dahisar) and southern zones like Colaba, dramatically reducing travel time by up to 60 minutes.
As of April 2025, the project has completed 59% of its construction milestones, with the corridor scheduled to become fully operational by December 2026, according to India Today.
Once operational, Metro Line 7A will transform airport access, facilitate inter-line metro transfers, and strengthen Mumbai’s standing as a modern, well-connected metropolis.
Source: News 18
