The Railway Ministry on Saturday shared the latest updates from the Mumbai-Ahmedabad Bullet Train project, highlighting what it called “precision engineering powering India’s Bullet Train project” as the cutterhead of the second Tunnel Boring Machine (TBM) was lowered at Sawli near Ghansoli in Maharashtra.
According to the ministry’s official update shared on X, the massive cutterhead has been installed for the 21-km underground section of the Mumbai-Ahmedabad High-Speed Rail (MAHSR) corridor. Earlier this week, the cutterhead for the first TBM was also lowered at Vikhroli in Mumbai.
The National High Speed Rail Corporation Limited (NHSCRCL), which is implementing the bullet train project, stated that the cutterhead weighs around 350 tonnes and has a diameter of 13.6 metres. The lowering of the cutterhead marks the completion of the primary assembly stage of the TBM’s main shield.
According to the NHSRCL’s official release, the second TBM will begin tunnelling work from Sawli (Ghansoli) and move towards Vikhroli. Both TBMs will now undergo final assembly and commissioning trials before starting their initial tunnelling drive in the first week of July 2026.
Precision engineering powering India’s Bullet Train project!
The 350-tonne cutterhead of the second Tunnel Boring Machine has been lowered at Sawli (Ghansoli) near Mumbai for the 21 km underground section of the #MAHSR corridor. Earlier this week, the cutterhead for the first… pic.twitter.com/VMWqEuJjgV
— Ministry of Railways (@RailMinIndia) May 23, 2026
What makes the TBM important for the Bullet Train project?
NSHRCL stated that the 13.6-metre-wide cutterhead has been specially designed to dig a single large tunnel capable of accommodating both the up and down railway lines of the high-speed rail corridor.
The cutterhead consists of 84 cutter discs, 16 bucket lips, 124 scrapers, which are used to cut soil and rock and remove excavated material during tunnelling operations.
The agency stated that two TBMs have been brought for the underground section of the project. TBM-1 is of 3,080 tonnes, whereas TBM-2 weighs approximately 3,184 tonnes.
How will the TBMs operate underground?
According to NHSRCL, the machines are Mix Shield or slurry-based TBMs, a technology which is usually used for tunnelling in tough geological and water-bearing ground conditions, especially in densely populated urban areas.
Each TBM measures 95.32 metres in length and is equipped with crucial components like cutter wheel, erector, main shield, jaw crusher, main bearing, tail shield and four specialised gantries that support excavation work.
NHSRCL said the TBMs can function at a maximum cutterhead speed of 4 revolutions per minute (RPM) and excavate up to 49 millimetres per minute. The machines have been designed to ensure controlled tunnelling progress while maintaining safety during underground construction work.
The Mumbai-Ahmedabad High-Speed Rail corridor is India’s first bullet train project and is being developed with Japanese Shinkansen technology. The corridor will interlink Mumbai in Maharashtra with Ahmedabad in Gujarat through a high-speed rail network aimed at reducing travel time significantly.