Chennai Metro Phase 2’s 1st TBM S96 Starts Tunneling

Tata Projects Ltd. (TPL) on Thursday commissioned S-96 – the first of 23 tunnel boring machines for the 118.9 km Chennai Metro Phase 2 project at at Chennai’s Madhavaram neighborhood.

This Ø6.61m Terratec earth pressure balance (EPB) machine for Package TU01 had passed factory acceptance tests (FAT) in China this summer and arrived on-site in July. TPL’s local team then in September started lowering the machines’ shields for its initial drive.

Speaking to TOI, CMRL’s Director (Projects), T Archunan, said “the soil condition on corridor-3 is sandy, silty and marine clayey from Madhavaram to Kellys and rocky soil from Kellys to Taramani. At Taramani, we are seeing rock at a shallow depth. The TBMs may be able to move at an average of only three meters a day if the soil is rocky. In phase-1, we encountered rock only during underground station construction. But in phase-2, we are seeing it during tunneling itself.”

S96 along with 6 other TBMs will construct approximately 9 km twin tunnels (total 18 km) on the new 45.813 km Line-3’s Venugopal Nagar – Kellys section.

TPL was awarded Phase 2’s Package TU-01 Rs. 1999 crore contract by CMRL in May 2021 with a 42 month deadline.

Scope of TU01: Construction of approximately 9 km twin bored tunnels (total = 18 km) from the TBM Retrieval Shaft near Venugopal Nagar (of Line-5) to Kellys Station, and the construction of diaphragm walls, entry/exit structures of Madhavaram Milk Colony Station, Murari Hospital Station, Ayanavaram Station and Purasaiwakkam High Road Station, including launching and retrieval shafts at the above stations.

Local news video with some excellent visuals:

Following its initial drive (roughly 60-120m, exact figure remains unknown), the machine’s back-up gantry will be lowered and attached for the main drive.

Back in September, S96’s sister machines S97 and S98 arrived at Chennai Port. Parts of one of them is shown in the video above inside the launch shaft.

Tata’s tunneling plan (drive lengths, timeframe) with 7 TBMs still remains unknown to me at this time. If someone reading this is aware, then leave a comment below or shoot me a message via the Contact page.

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– TMRG