Second Tunnel Boring Machine Starts to Excavate India’s First Undersea Tunnel beneath Thane Creek in Maharashtra for Mumbai–Ahmedabad Bullet Train Project

On 18 July 2026 the Ministry of Railways reported that a second Tunnel Boring Machine (TBM) has begun excavating the under‑sea portion of the Mumbai‑Ahmedabad Bullet Train corridor beneath Thane Creek, Maharashtra. The project includes a 10 km stretch, of which 7 km will be undersea, marking India’s first rail undersea tunnel. The TBM, a 13.6 m diameter, 3,200‑tonne Mixshield‑type machine, employs slurry‑based pressurised bentonite to stabilise the face and features real‑time multi‑gas monitoring and extensive safety systems. The launch required a 39‑m deep shaft and integrates advanced segment‑ring building and monitoring technologies to ensure structural integrity and minimise surface settlement.