Chennai Metro Phase 2: Nilgiri TBM breaks through at Moolakadai

Chennai, 6 August 2026 — Chennai Metro Rail Limited (CMRL) has reported that tunnel boring machine Nilgiri (S 96) has successfully completed tunnelling on the up line between Madhavaram High Road and Moolakadai Metro stations and reached Moolakadai station box.

The about 819-metre drive falls under Corridor 3 of Phase 2 — specifically the first roughly 9 km underground package from Madhavaram Milk Colony to Kellys, being built by Tata Projects under contract TU-01. CMRL describes the Moolakadai arrival as the 11th TBM breakthrough under that package and part of 24 Phase 2 TBM breakthroughs completed so far across the project.

Corridor 3 is the north–south spine of Phase 2: Madhavaram Milk Colony to Siruseri SIPCOT, about 45.8 km in CMRL’s published project summary (about 19.1 km elevated and 26.7 km underground).

The Nilgiri breakthrough is on the northern underground head of that corridor — the Madhavaram–Kellys tunnelling package — not on the elevated OMR / SIPCOT end. In plain terms: machines are still assembling the buried twin tunnels that will eventually carry trains through dense North Chennai before the line continues south toward the IT corridor.

Nearby stations on this northern package include Madhavaram Milk Colony, Madhavaram High Road, Moolakadai and onward toward Kellys. Passenger service dates for these stations remain [unconfirmed] in public CMRL project materials cited here.

CMRL has said seven tunnel boring machines are mobilised for the first 9 km underground section from Madhavaram Milk Colony to Kellys under Tata Projects (TU-01). Machines on Corridor 3 are named after Tamil Nadu mountains and rivers. The seven TU-01 names published by CMRL for the northern package are:

TBMs are often launched, retrieved and redeployed. Nilgiri’s first major public milestone was the 1.4 km drive from Madhavaram Milk Colony to Madhavaram High Road (launched 13 October 2022, breakthrough 7 August 2023). The latest drive — Madhavaram High Road → Moolakadai (up line, ~819 m) — is a later assignment of the same machine family on the twin-tunnel alignment. Exact launch date for this second Nilgiri drive is [unconfirmed] in the press note summarised here.

Phase 2 is a joint Centre–State metro expansion implemented by CMRL, with multilateral lending supporting large packages:

• JICA has been tied to about 52.01 km (Madhavaram–Sholinganallur portion of Corridor 3 and Madhavaram–CMBT portion of Corridor 5), as a State Sector project in CMRL’s project-status note.
• The balance about 66.89 km (full Corridor 4 and remaining Corridor 3 & 5 sections) has been posed for funding from multilateral banks including ADB, AIIB and NDB.
• Day-to-day delivery on this stretch also involves the General Consultant team and contractor Tata Projects under TU-01.

Readers should treat funding labels as project-finance context, not as a claim that every local bore is paid from a single lender’s line.

Madhavaram High Road and Moolakadai sit on one of North Chennai’s busiest road spines — a mix of GNT Road / Inner Ring Road traffic, wholesale and logistics movement, and dense neighbourhood access. Peak-hour queues, canal-side constraints and utility conflicts are everyday facts of life here.

Boring under the Buckingham Canal and a live carriageway is exactly the kind of urban tunnelling that residents notice only when something goes wrong. CMRL’s note stresses that vibration and settlement stayed within permitted limits, continuous instrumentation was used, and more than 14 deep borewells were managed with alternate water supply so drinking-water access was not left hanging during the drive.

For people living above the alignment, the practical message is: this breakthrough reduces one underground construction risk on this short link — it does not yet mean metro trains are running under Moolakadai.

• Nilgiri completed ~819 m of up-line tunnel and entered the Moolakadai station structure.
• CMRL calls it the 11th TU-01 TBM breakthrough and the 24th Phase 2 TBM breakthrough overall so far.
• Works under Buckingham Canal and busy road sections were completed with monitoring; borewell mitigation was arranged.
• Officials present included CMRL AGM (Tunnels) Kolli Venkata Ramana, GC Chief Mapping Engineer PSS Naidu, Tata Projects Project Manager Vijaya Kumar, and other CMRL, Tata Projects and General Consultant staff.