The ceremony commemorating the tunnel breakthrough of the 3.4-km Line 7A of Mumbai Metro was attended by Maharashtra Chief Minister Devendra Fanavis.
Between Andheri East and Chhatrapati Shivaji Maharaj International Airport, the Mumbai Metropolitan Region Development Authority (MMRDA) Thursday broke through a tunnel on Line 7A. In front of MMRDA Metropolitan Commissioner Dr Sanjay Mukherjee, Chief Minister Devendra Fadnavis ceremoniously pushed the lever to achieve the breakthrough.
Running 3.4 kilometres, Line 7A extends the presently running Red Line 7: Dahisar East to Gundavali in Andheri East. Of the 2.5 km of 7A that will be underground, 0.94 km will be elevated with two stations: Airport Colony (elevated) and CSMIA Terminal 2 (underground). Once finished, the corridor will also provide connection from Mira-Bhayander to the airport, linking via Metro Lines 9 and 7.
After completing the 1.647-km downline tunnel drive, which began in September 2023, a tunnel boring machine (TBM) called Disha broke through. Starting from a depth of 30 metres, the TBM has faced a number of engineering challenges during its underground journey including crossing Metro Line 3, burrowing under the Sahar elevated traffic ramp, and passing by key utilities including water mains and sewage pipes.
The finished tunnel links the north-south and east-west metro corridors of the city, hence enabling seamless transfers to Metro Line 1 (Versova-Ghatkopar) and he Metro Line 3 (Colaba-Seepz) via the subterranean station.
Watching this tunnel breakthrough, which is part of the most significant confluences of Mumbai Metro in the airport region, was exciting. Getting this tunnel across a challenging subsurface area calls great engineering genius. “And with such milestones, it will be our effort to open about 150 km of Metro lines by next year,” Fadnavis said during the breakthrough event.
MMRDA used sophisticated techniques including micro-tunnelling, TAM grouting—for underground soil reinforcement and continuous monitoring instrumentation to satisfy unanticipated soil strata and unmapped utilities—along with J Kumar Infraprojects Limited (JKIL), IIT Bombay and Brihanmumbai Municipal Corporation (BMC). In several locations, the TBM operated with just 1.2 metres of cover under subways while guaranteeing constant maximum safety.
Dr. Nalin Gupta, managing director of JKIL and project leader, remarked, “The arrival of Disha at the Bamanwada retrieval shaft marks a huge step in the delivery of th Mumbai Metro Tunnel.”
The Airport Authority of India (AAI) allocated the required land in October 2021; later, some 200 hutments from locations including Bamanvada and Vile Parle were rehabilitated to make room for the project.
Currently, Metro Line 7A’s physical construction is at 59 per cent. Sources say the line should be available to the public by December 2026. Upon completion, it would provide direct metro connection to the new Navi Mumbai International Airport via the integrated metro system hence decongesting road traffic to the airport.
The 337-km Mumbai Metro project is gradually taking shape as lines 1, 2A, and 7 are already operational and others like 2B, 4, 5, 6, 9, and 12 are in different construction phases.
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