Chennai Metro: Noyyal TBM Achieves Breakthrough at Mandaveli Station

Chennai Metro Rail Limited (CMRL) 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 0n February 7, 2026.

Noyyal TBM Breakthrough – Mandaveli Station
- Project: Chennai Metro Rail Phase 2, Corridor-3
- Milestone: Downline Tunnel Boring Machine (TBM) Noyyal achieved breakthrough at Mandaveli shaft on 7 February 2026.
- Earlier Achievement: Upline TBM Vaigai broke through on 18 October 2025.
- Contract: TU-02, marking the 8th TBM breakthrough under this package.
- Contractor: Larsen & Toubro Ltd.

Technical Details
- Tunnel Length: 763 metres (Greenways → Mandaveli).
- Geology: Predominantly silty sand and sandy soil.
- Method: Operated mainly in closed-face mode.
- Challenges:
- Passed beneath 75 buildings with shallow overburden (9–12 m).
- Navigated major underground utilities (sewer, water, electrical).
- Interventions: 14 cutterhead interventions on TBM Noyyal.
- Duration: 449 days (excluding waiting near shaft).

Significance
- Reinforces steady progress in Phase 2 implementation.
- Demonstrates engineering precision in densely built-up urban areas.
- Adds momentum to Chennai Metro’s expansion, improving connectivity across the city.

This breakthrough is a strong indicator that Phase 2 is moving forward despite complex ground conditions and utility challenges.