Mumbai-Ahmedabad Bullet Train Milestone: 350-Tonne Cutterhead Lowered For India's First Undersea Rail Tunnel

Mumbai-Ahmedabad Bullet Train Milestone: 350-Tonne Cutterhead Lowered For India's First Undersea Rail Tunnel

The Mumbai-Ahmedabad Bullet Train project achieved a major milestone after engineers lowered a 350-tonne Tunnel Boring Machine cutterhead at Vikhroli on Saturday. The 13.6-metre-wide TBM will excavate part of the 21-km underground corridor between BKC and Thane, including India’s first undersea rail tunnel beneath Thane Creek.

Abhishek PathakUpdated: Sunday, May 17, 2026, 06:38 PM IST
Mumbai-Ahmedabad Bullet Train Milestone: 350-Tonne Cutterhead Lowered For India's First Undersea Rail Tunnel
Mumbai-Ahmedabad Bullet Train Milestone: 350-Tonne Cutterhead Lowered For India's First Undersea Rail Tunnel |

The Mumbai-Ahmedabad Bullet Train project achieved a major engineering milestone on Saturday with the lowering of a massive 350-tonne cutterhead of a Tunnel Boring Machine (TBM) at Vikhroli in Mumbai. The cutterhead, measuring 13.6 metres in diameter, will be used to dig a key section of the underground tunnel connecting Bandra-Kurla Complex (BKC) and Thane as part of the country’s first high-speed rail corridor.

Final Major Component of TBM Assembly

The cutterhead forms the front portion of the TBM and is the final major component of the machine’s primary assembly. Two giant TBMs, each weighing more than 3,000 tonnes, are currently being assembled for construction of the 21 km long underground stretch in Mumbai. This includes a 7-km undersea tunnel below Thane Creek the first underwater rail tunnel in India.

Officials said the cutterhead was brought to Mumbai in five separate shipments and assembled at the site using around 1,600 kg of specialised welding. The machine is fitted with 84 cutter discs, 124 scrapers and 16 bucket lips that help cut rock and remove excavated soil during tunnelling.

TBM to Bore 6 km from Vikhroli to BKC

The TBM will bore nearly 6 km from Vikhroli towards the under-construction bullet train station at BKC, passing beneath densely populated areas and the Mithi river. The 13.6-metre diameter allows both up and down railway lines to be accommodated inside a single tunnel, making it one of the largest rail tunnelling machines ever used in India.

To ensure safety during excavation, authorities are using advanced monitoring systems such as settlement sensors, tilt meters, strain gauges and vibration monitoring instruments to track ground movement and nearby structures in real time.

The Mumbai underground section is considered one of the most complex parts of the ₹1.08 lakh crore Mumbai-Ahmedabad High-Speed Rail project. Once completed, the corridor is expected to significantly reduce travel time between Mumbai and Ahmedabad while introducing Japan’s Shinkansen-style high-speed rail technology to India.

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