L&T’s Chennai Metro TBM Adyar Records Breakthrough at Adyar Junction

Larsen & Toubro (L&T) on February 13 celebrated tunnel boring machine S-1326A’s first breakthrough at Adyar Junction Station for the 116.1 km Chennai Metro Phase 2 project.

This milestone, which went unreported by Chennai Metro Rail Ltd. (CMRL), marks the forth tunnel breakthrough for 45.8 km Chennai Metro Line-3‘s 12 km Package TU-02 connecting Kellys and Taramani Road Junction stations.

Nicknamed Adyar, TBM S-1326A is a 100m long Ø6.65m Herrenknecht earth pressure balance (EPB) machine which had passed factory acceptance tests (FAT) at Herrenknecht’s Alinjivakkam facility in July 2022.

TBM Adyar was commissioned from Greenways Road Station in April 2023 and built a 1218m tunnel for the up-line through difficult mixed geological conditions in 22 months. This includes a roughly 300m tunnel below Adyar River with an overburden of 10-13m.

Chennai Metro Rail Ltd. (CMRL) had awarded L&T with Package TU-02’s Rs. 2385 crore contract in May 2021 with a 42 month deadline.

Besides constructing twin tunnels between Kellys and Taramani Road Junction, they will build diaphragm walls, entry/exit structures of Chetpet Station, Royapettah Government Hospital Station, Thiruvanmiyu Station, and part diaphragm wall of Greenways Road Station, including launching and retrieval shafts at the above stations.

TBM Adyar is 1 of 8 machines deployed by L&T for building approximately 12 km twin tunnels (total 24 km) between Kellys and Taramani Road Junction stations.

Adyar’s sister machine Kaveri (S-1327A) had built the parallel 1228m down-line tunnel from Greenways and arrived at Adyar Junction in September 2024.

With this development, a total of 10 tunnels for Line-3 have been completed so far. On the south-side, L&T has recorded four breakthrough on Package TU-02 (Kellys to Taramani Road Junction):

• August 2024: TBM DZ1040 (Siruvani) at Sterling Road – 703m
• September 2024: TBM S-1327A (Kaveri) at Adyar Junction – 1228m
• October 2024: TBM DZ1041 (Palar) at Sterling Road – 700m
• February 2025: TBM S-1326A (Adyar) at Adyar Junction – 1218m

While on the north-side, Tata Projects has built 6 tunnels for Package TU-01 (Madhavaram – Kellys). 4 of those connect Venugopal Nagar – Madhavaram Milk Colony – Madhavaram High Road stations on the extreme north side, a length of roughly 2.5 km including station boxes.

• June 2023: TBM S98 (Anaimalai) at Venugopal Nagar – 415m
• August 2023: TBM S96 (Nilgiri) at Madhavaram High Road – 1.4 km
• September 2023: TBM S99 (Servarayan) at Venugopal Nagar – 415m
• November 2023: TBM S97 (Podhigai) at Madhavaram High Road – 1.4 km
• June 2024: TBM S98 (Anaimalai) at Otteri Station – 925m
• August 2024: TBM S81B (Kolli) at Otteri Station – 903m

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– TMRG