Mumbai-Ahmedabad Bullet Train: First Breakthrough Achieved in 5 km NATM Tunnel Under Thane Creek
Mumbai, 20 September 2025: A major milestone has been achieved in India’s first Bullet Train project with the breakthrough of a 4.881 km NATM (New Austrian Tunnelling Method) tunnel between Savali shaft and Shillphata portal. This tunnel is part of the 21 km undersea tunnel between BKC and Shillphata, which includes a 7 km stretch beneath Thane Creek.
The NATM tunnelling for this section commenced in May 2024 from three excavation faces, supported by an Additionally Driven Intermediate Tunnel (ADIT) that enabled simultaneous excavation from Ghansoli and Shillphata sides. The first breakthrough for a 2.7 km stretch was recorded on July 9, 2025, and with the latest achievement, a continuous 4.881 km tunnel is now complete.
The NATM tunnel has an internal excavation width of 12.6 metres and will connect to the viaduct portion of the Mumbai-Ahmedabad High-Speed Rail (MAHSR) project at Shillphata. Excavation was carried out using drilling and blasting techniques, supported by survey works, systematic support systems, and comprehensive monitoring instruments including ground settlement markers, piezometers, inclinometers, and strain gauges.
Strict safety measures were implemented at the site, with restricted access to construction zones, provision of controlled ventilation through fresh air pumping, and protocols to safeguard workers during tunnelling in complex geological conditions.
The remaining 16 km of the BKC–Shillphata tunnel will be constructed using Tunnel Boring Machines (TBMs). This section will feature a single-tube tunnel of 13.1 metres diameter to accommodate twin tracks for both up and down lines.
Project Progress Update
The 508 km Mumbai–Ahmedabad High-Speed Rail corridor is under construction with significant advancements across multiple segments:
321 km of viaduct and 398 km of pier works completed
17 river bridges and 9 steel bridges constructed
Over 4 lakh noise barriers installed along 206 km of stretch
206 track km of track bed construction completed
More than 2000 OHE masts installed covering approximately 48 km of viaduct
Excavation work underway on 7 mountain tunnels in Palghar district
Superstructure works at all Gujarat stations in advanced stages; work started on three elevated stations in Maharashtra with base slab casting in progress at Mumbai underground station
