Shilphata (Maharashtra) [India] July 11 : On July 9, the first breakthrough was achieved in the 21 km long tunnel being constructed between Bandra-Kurla Complex (BKC) and Shilphata in Maharashtra, marking the successful completion of a 2.7 km continuous tunnel section.
Out of the total 21 km tunnel, 5 km is being constructed using the New Austrian Tunnelling Method (NATM) between Shilphata and Ghansoli, while the remaining 16 km will be built using Tunnel Boring Machines (TBMs). The tunnel also includes a 7 km long undersea section beneath Thane Creek.
To expedite tunnelling in the NATM portion, an Additionally Driven Intermediate Tunnel (ADIT) was constructed, allowing simultaneous excavation towards Ghansoli and Shilphata sides. So far, about 1.62 km has been excavated from the Shilphata side, and the total progress in the NATM section stands at approximately 4.3 km.

Comprehensive safety measures have been implemented at the site, including ground settlement markers, piezometers, inclinometers, strain gauges, and biometric access control systems to ensure safe and controlled tunnelling activities without disturbing nearby structures.
The work on the Mumbai-Ahmedabad high-speed bullet train project is going on in full swing in Maharashtra, with major structural and tunnelling milestones being achieved, according to the National High-Speed Rail Corporation Limited (NHSRCL) said on Saturday.
According to the NHSRCL, work on all three elevated stations in the state, Thane, Virar, and Boisar, is advancing swiftly, and the first slabs for Virar and Boisar stations have recently been cast. Across the alignment, pier foundations and pier works are underway at various locations, with approximately 44 km of piers cast to date.
In the Palghar district, viaduct construction has also commenced using full-span box girder launching technology, starting from the Dahanu area. Additionally, the excavation of seven mountain tunnels in the Palghar district is actively in progress, demonstrating the project's engineering scale and complexity. Bridge construction has also kicked off at three major rivers: Vaitarna, Ulhas, and Jagani, further contributing to the corridor's critical infrastructure.
An important component of the project is the 21-kilometre-long underground and undersea tunnel connecting the Mumbai Bullet Train station at Bandra-Kurla Complex (BKC) to Shilphata. Of the 21 km tunnel, 16 km is being excavated using Tunnel Boring Machines (TBMs), while 5 km is being executed using the New Austrian Tunnelling Method (NATM). The tunnel includes a 7 km undersea stretch beneath Thane Creek, marking a significant feat in Indian tunnelling history.
So far, approximately 4.1 km of tunnel heading has been achieved through NATM from the Shilphata site, and two concurrent faces have been developed from the ADIT portal. In terms of vertical construction, base slab casting at the Vikhroli shaft (56 meters deep) and Sawli shaft (39 meters deep) has been completed. Additionally, sludge treatment plants are being installed at shaft locations, and the Mahape tunnel lining casting yard is actively producing tunnel lining segments.
For the under-construction Mumbai Bullet Train station at Bandra Kurla Complex, 80% of the excavation work has been completed. Base slab casting at 100 ft below ground level has already started at both ends of the station site, NHSRCL added.