Noyyal TBM Breaks Through at Mandaveli Station in Chennai Metro Phase 2
Chennai Metro Rail Limited (CMRL) marked a key milestone in Phase 2, Corridor-3, with the successful breakthrough of the Downline Tunnel Boring Machine (TBM) “Noyyal” at the Mandaveli shaft on 07 February 2026.
Tunnelling between Greenways Road Station and Mandaveli Station began in September 2023, using two TBMs — Noyyal (Downline) and Vaigai (Upline). While TBM Vaigai achieved its breakthrough earlier on 18 October 2025, Noyyal has now completed its drive, marking the 8th TBM breakthrough under the TU-02 contract.
The 763-metre-long tunnel, executed by Larsen & Toubro Ltd, passes beneath densely populated areas, including 75 buildings, with an overburden of 9–12 metres. Construction near the Mandaveli shaft was particularly challenging due to major underground utilities such as sewer lines, water pipelines, and electrical cables, requiring meticulous planning and extended timelines.
TBM Noyyal navigated mainly silty sand and sandy soil conditions, operating largely in closed-face mode. The drive involved 14 cutterhead interventions and was completed in 449 days, excluding the waiting period for shaft construction.
This achievement underscores steady progress in the execution of Chennai Metro Rail Phase 2 works.
