Major Leap for Bullet Train: Vaishnaw Launches Undersea Tunnel Work in Mumbai

The inaugural boring operation began from Vikhroli, heading towards the Bandra Kurla Complex (BKC) station in Mumbai. This critical section forms part of a larger 20.37-kilometre tunnel, which famously includes a challenging 7-kilometre undersea stretch.

Colossal TBMs Begin Operation

Two specially customised German-made TBMs are at the heart of this operation. These colossal machines, owned by Afcons Infrastructure Limited, made their way to India via sea from China in March 2026. Officials noted that the Railway Minister personally pressed the button to start the TBM, stationed 56.6 metres below ground at Vikhroli.

These aren't your typical metro TBMs. With a massive cutter head diameter of 13.6 metres, they are among the largest and most expensive ever used in any Indian railway project. Each TBM is expected to excavate about 300 metres of tunnel every month. A senior railway expert anticipates around 600 metres of tunnelling monthly once both machines are fully operational.

Strategic Tunnelling and Depth

The first TBM will tackle approximately 5.8 kilometres from Vikhroli towards BKC. The second machine is currently being assembled at Sawli and is set to begin its 9.7-kilometre excavation shortly. This second leg includes the crucial 7-kilometre undersea section, connecting Sawli to Vikhroli.

The entire 20.37-kilometre tunnel will accommodate twin tracks within a single tube, designed for bi-directional traffic. It will be constructed at an average depth of about 65 metres below ground level. For construction access, two shafts have been prepared at Vikhroli (56 meters deep) and Sawli (39 meters deep).

Project Breakdown and Afcons' Expertise

While TBMs will handle 15.4 kilometres between BKC and Sawli, a 4.8-kilometre stretch from Sawli to Shilphata has already been completed. This earlier section utilized the traditional drill-and-blast method. The project also entails building 39 equipment rooms at 37 locations alongside the tunnel.

Afcons Infrastructure, the company undertaking this complex package, has a history of executing challenging projects. Their portfolio includes the iconic Chenab bridge, India's first under-river tunnel for the Kolkata Metro, and the all-weather Atal Tunnel. Their expertise is vital for this ambitious undertaking.

Transforming Intercity Travel

The Mumbai-Ahmedabad High-Speed Rail Corridor, spanning 508 kilometres, is set to redefine intercity travel. Trains running at speeds up to 320 kmph will link major economic hubs like Mumbai, Vapi, Surat, Anand, Vadodara, and Ahmedabad.

Starting from Mumbai's Bandra Kurla Complex, the corridor will feature stations at Thane, Virar, Boisar, Vapi, Bilimora, Surat, Bharuch, Vadodara, Anand, Ahmedabad, and Sabarmati. Limited-stop services, halting only at Surat, Vadodara, and Ahmedabad, are projected to complete the journey in approximately 2 hours and 7 minutes, drastically cutting current travel times.

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