Tata’s TBM S81B Records Chennai Metro Phase 2’s 7th Breakthrough

It’s a season of breakthroughs! Besides Afcons in Agra, Tata Projects Ltd. (TPL) in Chennai on Thursday celebrated tunnel boring machine S81B’s first tunnel breakthrough at Otteri Station for the 116.1 km Chennai Metro Phase 2 project.

Nicknamed TBM Kolli, this Ø6.61m diameter Terratec Earth Pressure Balance (EPB) machine after a stint in Pune Metro had passed factory acceptance tests (FAT) in December 2022 for its second deployment in Chennai.

It was launched from 45.8 km Chennai Metro Line-3’s Ayanavaram Station’s South Shaft in July 2023 and took roughly 13 months to build the 903m up-line towards Otteri Station.

Per CMRL’s press release, the TBM’s drive included negotiating a sharp 220m radius curve and followed by another 280m radius curve. The machine passed through a densely populated area and addressed more than 100 bore wells along its alignment.

Chennai Metro Rail Ltd. (CMRL) had awarded Tata Projects with Package TU-01’s Rs. 1999 crore contract in May 2021 with a 42 month deadline.

TBM Kolli along with 6 other TBMs will build approximately 9 km twin tunnels (total 18 km) on Line-3’s Venugopal Nagar – Kellys underground section. The scope also includes construction of diaphragm walls, entry/exit structures of Madhavaram Milk Colony Station, Murari Hospital Station, Ayanavaram Station and Purasaiwakkam High Road Station.

Tata Projects has so far completed building 6 tunnels for Package TU-01. 4 of those connect Venugopal Nagar – Madhavaram Milk Colony – Madhavaram High Road stations on the north side, a length of roughly 2.5 km including station boxes.

Here’s a recap of all tunnel breakthroughs recorded so far:

• 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 (this post!)

On the south-side, L&T has so far recorded one breakthrough for Line-3 on Package TU-02 (Kellys to Taramani Road Junction):

• August 2024: TBM DZ1040 (Siruvani) at Sterling Road – 703m

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– TMRG