With the arrival of the first tunnel boring machine (TBM) in the city from China, Chennai Metro Rail Limited (CMRL) gears up to build the underground network for the phase II project.
Incidentally, the first TBM for the phase I project — currently operation and spanning 45 km of the city — also came from China and was launched at Nehru Park in July 2012, exactly 10 years ago.
According to CMRL officials, TBMs are an integral part of any Metro Rail project as it bores the earth, builds tunnels and helps in creating the underground network for the system. The machines, which weigh anywhere between 800-1,000 tonnes, can measure nearly 90 m in length. This means, a TBM can be almost as tall as a 30-storey building.
A total of 23 such TBMs will be needed for the phase II project, and the other machines will arrive in the coming months, officials said.
The TBM, which is currently at Chennai Port, will soon be taken to Madhavaram and assembled. This exercise will take close to three months; the tunnelling is expected to start in October.
The phase II project, which runs for 118.9 km at a cost of ₹61,843 crore, has three corridors — Madhavaram to SIPCOT via Kellys (corridor 3), Madhavaram to Shollinganallur (corridor 5) via Medavakkam and Light House to Poonamallee via T. Nagar (corridor 4).
“The TBM will be launched at Madhavaram for the construction of corridor 3 and will tunnel towards Kellys. For the stretch between Madhavaram to Kellys, a 9-km twin tunnel will be created. While, one has landed here, another one is expected soon. It may take months for the TBM launched at Madhavaram to reach Kellys, and the time taken will depend primarily on the geological conditions.
“Another TBM is getting refurbished and readied at Gummidipoondi and will be used for tunnelling between Kellys and Taramani,” an official said.
This TBM has been brought down to the city after it received the Factory Acceptance Test approval from CMRL recently.
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