DELHI (Metro Rail News): The Mumbai-Ahmedabad bullet train project moved a step ahead after engineers lowered the cutterhead of the second Tunnel Boring Machine (TBM) at Sawli near Ghansoli in Maharashtra. This giant machine will help build the 21 km underground tunnel section near Mumbai. Officials plan to start tunneling work from Sawali towards Vikhroli in July 2026 after completing final assembly and testing.
Project Snapshot
| Details | Information |
| Project | Mumbai-Ahmedabad Bullet Train |
| Tunnel Length | 21 km |
| Location | Sawli (Ghansoli), Maharashtra |
| Tunnel Direction | Sawli to Vikhroli |
| Cutterhead Diameter | 13.6 meters |
| Cutter Weight | 350 tonnes |
Second TBM enters final assembly stage
Engineers lowered the huge cutterhead at the launch shaft in Sawli. This marks the last major step before the full assembly of the TBM. Earlier this week, officials lowered the cutterhead for the first TBM at Vikhroli. Both machines will now go through,
- Final assembly
- Testing and commissioning
- System checks before tunneling starts
Officials expect the initial tunnel drive to begin in the first week of July 2026.
The TBM has a cutterhead diameter of 13.6 meters. It can dig a single large tunnel that will carry both up and down bullet train tracks. The cutterhead includes 84 cutter discs, 124 scrapers and 16 bucket lips. These parts help the machine cut through soil and rock while clearing debris during excavation.
Key details about the TBMs
| Features | Details |
| Number of TBMs | 2 |
| Weight of TBM 1 | 3,080 tonnes |
| Weight of TBM 2 | 3,184 tonnes |
| TBM Type | Mix shield/ Slurry-based |
| Length of each TBM | 95.32 meters |
Each TBM includes several major systems such as cutter wheel, main bearing, jaw crusher, main shield, tail shield, and four specialised gantries. The machines can run at a cutterhead speed of up to 4 RPM and dig up to 49 mm per minute.
The underground stretch near Mumbai remains one of the most challenging parts of the bullet train project because of dense urban areas and difficult ground conditions. Officials are using advanced slurry based TBMs to carry out tunnelling safely and smoothly.
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