The Mumbai-Ahmedabad high-speed rail project reached a significant construction milestone as the second TBM commenced excavation from Sawli in Ghansoli towards Vikhroli. The TBM will form part of the underground corridor and will construct the section beneath Thane Creek, which will be India’s first undersea high-speed rail tunnel. The work is part of broader tunnelling efforts to link key urban nodes. The TBM is one of the largest deployed for railway tunnelling in India and will operate alongside other machines to complete the 21 kilometre underground tunnel. Of that length, 16 kilometres between Sawli and Bandra-Kurla Complex will be excavated using TBMs, while the remaining sections will use conventional methods. The first TBM began tunnelling from Vikhroli towards Bandra-Kurla Complex earlier this month. The machine is a Mixshield type that uses advanced slurry technology to stabilise the tunnel face and minimise ground disturbance in Mumbai’s densely populated suburbs. A 39 metre deep shaft was constructed at Sawli to launch the TBM, which was lowered underground and assembled in phases to begin the drive. Project authorities have outlined careful ground monitoring and safety protocols for the tunnelling operations. The undersea section beneath Thane Creek will require specialised lining and waterproofing measures and the project team has planned logistics accordingly. The tunnelling milestone follows preparatory civil works, station designs and utility diversions that have been coordinated with local agencies. The completion of the underground corridor is central to delivering the high-speed link between Mumbai and Ahmedabad on schedule. Safety monitoring systems and continuous geotechnical surveys will be employed during tunnelling to protect existing buildings and infrastructure. Coordination with municipal authorities and utility providers has been intensified to manage traffic and services during construction. The project maintains staged work plans and contingency procedures to reduce disruptions and maintain progress towards completion.