Mumbai: The Mumbai-Ahmedabad Bullet Train Project achieved a monumental construction milestone on Sunday as India’s largest tunnel boring machine officially commenced excavation from the Vikhroli shaft in Mumbai. The massive operation marks the very first deployment of a TBM for the nation’s maiden high-speed rail corridor. While a formal inauguration ceremony by Union Railway Minister Ashwini Vaishnaw was temporarily postponed due to severe monsoon rains and weather alerts in Mumbai, the National High Speed Rail Corporation Limited was directed to initiate the technical work immediately to ensure the multi-crore infrastructure project stays firmly on schedule.
The mega underground phase involves constructing a highly complex 21-kilometre subterranean stretch between the Bandra Kurla Complex and Shilphata, which uniquely includes India’s first 7-kilometre undersea rail tunnel beneath Thane Creek. Out of this total underground layout, a 16-kilometre section connecting Sawli in Ghansoli to BKC is being bored using heavy TBM machinery, while the remaining 5-kilometre portion has already been successfully carved out using the New Austrian Tunnelling Method. The newly launched Mixshield TBM will meticulously dig a 6-kilometre single-tube tunnel designed to simultaneously hold both the up and down tracks. Operating at depths ranging between 25 and 114 metres, the machine will navigate directly under dense urban landscapes, multi-storeyed buildings, major arterial roads, and the Mithi River, demanding exceptional precision and rigorous real-time structural monitoring.
This specialized German-made machine is a marvel of modern engineering, custom-built to tackle mixed geological terrain and immense groundwater pressure. Featuring a 13.6-metre-diameter cutterhead—equivalent to a four-storey building—the TBM weighs roughly 3,100 tonnes and spans 96 metres in length. To smoothly launch this mechanical giant, engineers excavated a massive 56-metre-deep shaft at Vikhroli, setting up specialized on-site support infrastructure including slurry and water treatment plants. A second TBM is currently being assembled at the Sawli shaft and is expected to join the workforce within the next fortnight. Together, the two machines are projected to excavate about 600 metres per month, accelerating progress toward the operational launch of the high-speed rail corridor.
