Chennai Metro Rail Limited (CMRL) marked a major milestone in Phase 2, Corridor-3 with the successful breakthrough of the Downline Tunnel Boring Machine (TBM) “Noyyal” at the Mandaveli shaft on 7 February 2026.
Tunnelling between Greenways Road Station and Mandaveli Station commenced in September 2023, with the deployment of two TBMs—“Noyyal” for the downline and “Vaigai” for the upline. The upline TBM Vaigai achieved its breakthrough earlier on 18 October 2025, while Noyyal has now successfully completed its drive.
This achievement marks the 8th TBM breakthrough under the TU-02 contract, reflecting steady progress in the execution of Chennai Metro Rail Phase 2.
The tunnel, constructed by M/s Larsen & Toubro Ltd, has a total length of 763 metres and passes beneath densely built-up urban areas, including below 75 buildings, with an overburden ranging between 9 and 12 metres. The Mandaveli shaft zone presented additional engineering challenges due to the presence of major underground utilities such as sewer lines, water pipelines, and electrical cables, necessitating meticulous planning and extended construction timelines.
During excavation, the TBMs encountered predominantly silty sand and sandy soil, and operations were carried out mainly in closed-face mode. A total of 14 cutterhead interventions were undertaken on TBM Noyyal. The tunnel drive was completed in 449 days, excluding the waiting period near the shaft for completion of shaft construction.
The breakthrough event was witnessed by Thiru. T. Archunan, Director (Projects), CMRL, in the presence of senior officials from CMRL, consultants, and representatives of M/s Larsen & Toubro Ltd, including:
-
Thiru. Anto Jos Menachery – GM (Underground)
-
Thiru. Livingstone Eliazer – CGM (PP&D)
-
Thiru. S. Ashok Kumar – CGM (T & EC)
-
Thiru. Ravichandran – GM (UG Stations)
-
Thiru. Subramanian – Consultant, DRE
-
Thiru. Lakshmi Prasad – Project Director, L&T
-
Thiru. Ahmet – Project Manager, L&T
