India, May 24 -- In a breakthrough for India's first bullet train corridor, engineers on Saturday lowered a gigantic 350-tonne cutterhead into the ground at Ghansoli's Sawli area, marking a crucial stage in the construction of the Mumbai-Ahmedabad High Speed Rail project.

The cutterhead, the massive rotating front portion of a Tunnel Boring Machine (TBM) that cuts through soil and rock, is part of the machine that will dig the project's ambitious 21-km underground tunnel stretch between Ghansoli and Vikhroli.

Officials from the National High Speed Rail Corporation Limited (NHSRCL) said the lowering of the 13.6-metre diameter cutterhead completes the primary assembly of the TBM's main shield, making it one of the most significant enginee...