Chennai Metro Rail Limited (CMRL) has achieved a significant milestone on Phase 2, Corridor‑3, with the downline Tunnel Boring Machine (TBM) Noyyal completing its breakthrough at the Mandaveli shaft. The drive forms part of the twin‑tunnel section between Greenways Road and Mandaveli, delivered under contract by Larsen & Toubro Limited.
Tunnelling on this stretch began in September 2023 using two TBMs: Noyyal for the downline and Vaigai for the upline. Vaigai achieved its breakthrough on 18 October last year, and Noyyal has now concluded its 763‑metre drive. This marks the eighth TBM breakthrough on Chennai Metro Phase 2, underscoring steady progress across the underground works.
The Greenways–Mandaveli alignment passes beneath densely built‑up neighbourhoods, with the tunnel running below 75 buildings and an overburden ranging from 9 to 12 metres. The Mandaveli shaft area presented additional engineering challenges due to the presence of major underground utilities, including sewer lines, water pipelines and electrical cables. The contractor implemented controlled excavation and continuous monitoring to maintain ground stability and protect existing infrastructure.
With both upline and downline drives now completed between Greenways and Mandaveli, the TU‑02 package continues to advance toward subsequent construction stages. Corridor‑3 will ultimately connect Madhavaram to Siruseri SIPCOT, forming a key north–south spine in Chennai’s expanding metro network.
Project Fact Box
Chennai Metro Rail Phase 2
Corridor: Corridor‑3 (Madhavaram–Siruseri SIPCOT)
Executing Agency: Chennai Metro Rail Limited (CMRL)
Contract Package: TU‑02
Contractor: Larsen & Toubro Limited
TBMs Used: Noyyal (downline), Vaigai (upline)
Breakthroughs:
Vaigai – 18 October 2025
Noyyal – February 2026
Tunnel Length: 763 metres (Greenways Road to Mandaveli)
Geology: Predominantly silty sand and sandy soil
Overburden: 9–12 metres
Structures Above Alignment: 75 buildings
Key Challenges: Dense urban environment, major underground utilities at Mandaveli shaft
Significance: Eighth TBM breakthrough on Chennai Metro Phase 2
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