Mumbai-Ahmedabad bullet train tunnel works have moved into another assembly stage, with NHSRCL lowering the cutterhead of the project’s second Tunnel Boring Machine in Navi Mumbai. The machine is being prepared to bore from Sawli towards Vikhroli in Mumbai.

Mumbai-Ahmedabad bullet train tunnel advances
Mumbai-Ahmedabad bullet train tunnel advances

Officials said on Sunday that the National High Speed Rail Corporation Limited completed the cutterhead lowering for the second TBM assigned to the tunnel section of the high-speed rail corridor. The work was carried out on Saturday at Sawli near Ghansoli.

NHSRCL prepares second TBM for Mumbai-Ahmedabad bullet train tunnel

According to NHSRCL, the 13.6-diameter cutterhead weighs 350 tonnes. Placing it into position completes the primary assembly stage for the TBM’s main shield.

The first Tunnel Boring Machine passed the same point last week, when its cutterhead was lowered at Vikhroli. With both cutterheads now installed, the two machines will move through final assembly and commissioning trials before excavation begins in the first week of July.

NHSRCL said the TBMs are designed to excavate one large tunnel capable of accommodating both the up and down lines of the high-speed rail corridor. Each cutterhead carries 84 cutter discs, 124 scrapers and 16 bucket lips, which are used for excavation and muck removal during tunnelling.

Navi Mumbai TBM cutterhead marks a technical milestone

The two units are slurry-based Mix Shield TBMs. One weighs 3,080 tonnes, the other 3,184 tonnes, and each machine is 95.32 metres long.

Their main components include the cutter wheel, main bearing, jaw crusher, erector, main shield and tail shield. Each machine also has four specialised gantries to support the tunnelling work.

The TBMs can run at a maximum cutterhead rotation speed of four revolutions per minute. NHSRCL said they can achieve an excavation rate of up to 49 mm per minute while maintaining safety standards.

India’s first undersea rail tunnel is part of the route

The machines are being assembled for a 16-km stretch of the 21-km Mumbai tunnel. Railway Supply previously covered the corridor’s move toward underground construction, including the TBM-driven section and the Thane Creek element.

This section includes a 7-km undersea tunnel beneath Thane Creek, described in the NHSRCL project overview as India’s first undersea rail tunnel.

Together, the two TBMs will form a central part of the Mumbai tunnel construction programme. Their commissioning will take the tunnel section from assembly preparation into the excavation phase planned for early July.