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Bowbazar Metro: Defunct tunnel boring machine to be extracted

The stretch between Bowbazar and Sealdah is the last leg of the underground tunnelling of the East-West Metro Corridor.

Statesman News Service | Kolkata |

The Kolkata Metro Rail Corporation Limited (KMRCL) has started the work on the retrieval shaft which will be used to extract the two tunnel boring machines at Bowbazar.

The tunnel boring machine(TBM) ‘Chandi’ became defunct after it hit an aquifer while digging ground for tunnel at Durga Pithuri Lane on 31 August 2019.

In the aftermath of the tragedy in Bowbazar where over 500 residents of the area were evacuated and shifted to various city hotels while 27 buildings were damaged beyond repair, several other structures were also impacted by subsidence of the ground underneath.

A large volume of water had gushed into Chandi, rendering it useless.

While the other TBM, ‘Urvi’ took up the task of excavating the remaining portion, covering a length of about 1.8 km. The stretch between Bowbazar and Sealdah is the last leg of the underground tunnelling of the East-West Metro Corridor.

Now, when the work in the remaining part of this tunnel resumed this week, the KMRCL engineers have also started the construction of the shaft that will be used to retrieve the defunct TBM

Chandi where it has been lying idle since the past one year.

According to an official of the implementing agency of the East-West Metro project, if everything goes fine, the shaft will be completed in eight months.

“The TBM Urvi is at a distance of about 500 metres from Sealdah Station where tunnelling is expected to be completed in two months.

After ‘Urvi’ completes the remaining part of the tunnel till Durga Pithuri Lane, it will be extracted through the same retrieval shaft” informed an official of KMRCL. ”