The National High Speed Rail Corporation (NHSRCL) has announced a significant milestone in the Mumbai-Ahmedabad bullet train project with the completion of a 2.7-km continuous tunnel section using the New Austrian Tunnelling Method (NATM).

This breakthrough, achieved on 09 July, 2025, marks the first major success in the construction of the 21-km tunnel between Mumbai’s Bandra-Kurla Complex (BKC) and Shilphata in Thane. The tunnel is a vital segment of the high-speed rail corridor, which includes a unique seven-km undersea section beneath Thane Creek. Of the total tunnel length, 16 km will be excavated using Tunnel Boring Machines (TBMs), while the remaining five km, primarily between Shilphata and Ghansoli, will use NATM techniques.

To expedite excavation in the NATM section, an Additional Driven Intermediate Tunnel (ADIT) was built, allowing work from both the Shilphata and Ghansoli sides. Currently, 1.62 km have been excavated from Shilphata, with total NATM progress reaching 4.3 km. The NHSRCL has implemented rigorous safety protocols, including ground settlement markers, piezometers, inclinometers, strain gauges, and biometric access systems, to ensure secure and efficient tunnel construction.