The Mumbai–Ahmedabad high-speed rail project recorded a major milestone on Saturday with the completion of a nearly five-kilometre tunnel between Ghansoli and Shilphata, marking a key step in the underground stretch of the corridor. Officials said the excavation used the New Austrian Tunnelling Method (NATM) to connect the Savali shaft with the Shilphata tunnel portal, forming part of the 21-km underground section from Bandra Kurla Complex (BKC) to Shilphata, which includes a seven-kilometre segment beneath Thane Creek.
Work on this tunnel began in May 2024 through three faces, with the first breakthrough recorded in July on a 2.7-km continuous stretch. With the latest progress, engineers have completed a 4.881-km section that will integrate with the viaduct at Shilphata. The tunnel has an excavation width of 12.6 metres and is designed as a single tube of 13.1 metres in diameter to carry twin tracks, enabling trains to run in both directions.
Officials noted that complex geological conditions made the breakthrough significant, with the excavation executed using drilling, controlled blasting, detailed surveys and robust support systems to maintain stability. Safety systems included settlement markers, piezometers, inclinometers and strain gauges to ensure controlled progress without affecting nearby structures. An Additional Driven Intermediate Tunnel (ADIT) allowed simultaneous drives from multiple ends to speed up the work, while on-site measures included restricted access and fresh-air pumping inside the tunnel.
With the NATM portion completed, focus will move to the remaining 16 km of tunnelling to be executed using Tunnel Boring Machines (TBMs). Overall, construction across the 508-km corridor continues to advance: 321 km of viaducts and 398 km of piers are complete, along with 17 river bridges and nine steel bridges. Over four lakh noise barriers have been installed along 206 km, track bed works are finished on 206 km, and more than 2,000 OHE masts have been erected across 48 km of viaduct. In Maharashtra, base slab casting is underway at the underground Mumbai station, while station superstructures in Gujarat are in advanced stages.
India’s first bullet train will span 508 km, sharply cutting travel time between Mumbai and Ahmedabad. With the Ghansoli–Shilphata breakthrough, the project moves closer to commissioning, reflecting the push toward modern high-speed rail infrastructure.
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