India’s largest rail TBMs deployed for Mumbai-Ahmedabad bullet train underground section: What we know

Marking a major milestone in the Mumbai-Ahmedabad bullet train project, a 350-tonne tunnel boring machine cutterhead was lowered at Vikhroli, beginning assembly of the underground tunnelling system phase development work.

The cutterhead weighs 350 tonnes and measures 13.6 metres in diameter, forming the front end of the TBM, delivered in five consignments and assembled using precision welding techniques onsite work.

Mumbai tunnel spans 21 km, with 16 km constructed using two massive TBMs, each weighing over 3,000 tonnes, designed to build a single tunnel carrying both up and down lines.

The project includes a 7 km stretch beneath Thane Creek, marking India’s first undersea rail tunnel, forming part of the high-speed corridor’s most complex underground section development engineering major challenge.

TBMs are the largest ever deployed in India for rail tunnel construction, setting a new benchmark in scale, capacity, and engineering capability for underground infrastructure development projects sector.

The cutterhead features 84 cutter discs, 124 scrapers, and 16 bucket lips, designed to break rock and soil, clear excavated muck efficiently, and guide material into the chamber pipeline system.

From Vikhroli, the TBM will excavate nearly 6 km towards Bandra-Kurla Complex, passing beneath dense urban areas and the Mithi River before being retrieved at the under-construction station complex site.