Bullet Train Project: First 350-tonne TBM cutterhead lowered at Vikhroli for Mumbai section
The Mumbai-Ahmedabad High Speed Rail (MAHSR) project reached a major milestone on May 17, 2026. The National High Speed Rail Corporation Limited (NHSRCL) successfully lowered the first 350-tonne Tunnel Boring Machine (TBM) cutterhead at the Vikhroli site in Mumbai. Union Railway Minister Ashwini Vaishnaw confirmed this development via X, noting that it is the largest TBM cutterhead ever used for rail projects in India.
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What are the technical details of the TBM cutterhead
The cutterhead measures 13.6 meters in diameter and was assembled on-site using 1,600 kg of high-precision welding after arriving in five shipments. It is designed to dig a single large tunnel that will house both the up and down tracks. The machine features specific tools for excavation:
- 84 cutter discs to break through hard rock
- 124 scrapers for clearing muck
- 16 bucket lips to collect excavated material
How will the Mumbai tunnel section be constructed
Two massive TBMs, each weighing over 3,000 tonnes, are being used to build a 16 km portion of the overall 21 km Mumbai tunnel. This includes India’s first 7 km undersea rail tunnel passing beneath Thane Creek. The Vikhroli TBM will dig approximately 6 km towards the Bandra-Kurla Complex (BKC), passing under the Mithi River and dense urban areas. To ensure safety, NHSRCL is using advanced monitoring tools like 3D Reflect Targets and Seismographs to protect nearby buildings.
| Feature | Details |
|---|---|
| Cutterhead Weight | 350 Tonnes |
| TBM Total Weight | Over 3,000 Tonnes |
| Mumbai Tunnel Length | 21 km (16 km by TBM) |
| Undersea Section | 7 km beneath Thane Creek |
| Cutterhead Diameter | 13.6 Meters |
Frequently Asked Questions (FAQs)
What is the purpose of the TBM at Vikhroli?
The TBM will excavate a 6 km stretch from Vikhroli to the Bandra-Kurla Complex (BKC), navigating under the Mithi River and urban areas.
What is special about the Mumbai tunnel section?
It includes India’s first undersea rail tunnel, which will be 7 km long and located beneath Thane Creek.