Chennai Metro Rail Limited (CMRL) has said that ti has achieved a significant milestone in Phase 2, Corridor-3, with the successful breakthrough of the downline Tunnel Boring Machine (TBM) “Noyyal” at the Mandaveli shaft on Feb.7.
In a post on social media, CMRL said that tunnelling between Greenways Road station ( in R. A. Puram) and Mandaveli station commenced in September 2023, deploying two TBMs, called “Noyyal” and “Vaigai.”
While the upline TBM called Vaigai achieved its breakthrough in October 2025, the downline TBM Noyyal completed its drive on February 7
The tunnel, executed by M/s Larsen & Toubro Ltd, has a total length of 763 metres and passes beneath densely built-up areas, including below 75 buildings.
CMRL said that the Mandaveli shaft area posed additional challenges due to the presence of major underground utilities such as sewer lines, water pipelines and power cables, necessitating careful planning and extended construction time.
The TBMs also encountered predominantly silty sand and sandy soil conditions.
