New Austrian tunnelling method achieves milestone breakthrough in BKC-Shillphata undersea tunnel project
In a significant milestone for the ambitious undersea tunnel project between BKC and Shillphata, the New Austrian Tunnelling Method (NATM) has successfully achieved a breakthrough for its 5 km tunnel stretch. This critical section, which runs 4.881 km, notably includes a challenging 7 km segment beneath the Thane Creek. Tunneling commenced in May 2024, and on July 9, engineers celebrated the first breakthrough for a continuous 2.7 km section, connecting the ADIT to the Savali shaft. With this achievement, excavation is now complete between the Savali shaft and the tunnel portal at Shillphata, paving the way for the tunnel’s integration with the viaduct segment of the Mega Airport High-Speed Rail (MAHSR) project. To accelerate the process, an Additional Driven Intermediate Tunnel (ADIT) was constructed, enabling simultaneous excavation from both Ghansoli and Shilphata sides.The remaining 16 km of tunnelling will be executed using Tunnel Boring Machines (TBMs). The tunnel will be a single tube tunnel of 13.1 meters in diameter to accommodate twin track for both up and down lines.Comprehensive safety measures have been implemented at the site, including ground settlement markers, piezometers, inclinometers, and strain gauges to ensure safe and controlled tunnelling activities without disturbing nearby structures. Proper arrangements were made to restrict access to the tunnel construction sites, preventing unauthorised entry and ensuring the safety of workers within the sensitive and complex construction environment. Provisions were made for pumping fresh air inside the tunnel for the construction workers. India’s first 508 km long Bullet Train corridor, connecting Mumbai and Ahmedabad, is making significant progress. Out of the total length of 508 km, 321 km of viaduct and 398 km of pier work have already been completed. Additionally, all 17 river bridges and 9 steel bridges have been finished. To enhance noise control, more than 400,000 noise barriers have been installed along a 206 km stretch. The construction of 206 km of track bed has also been completed, alongside the installation of over 2,000 OHE masts, which cover approximately 48 km of the mainline viaduct. Currently, excavation work is ongoing for 7 mountain tunnels located in Palghar district. Meanwhile, the superstructure work on all stations in Gujarat is at an advanced stage, and construction has commenced on all three elevated stations, with base slab casting in progress at the Mumbai underground station in Maharashtra.
