BENGALURU: In the midst of the all-round slump in activity all around due to the second COVID wave, a major infrastructure work kickstarted 60 feet below the ground on Friday evening. The tunnelling operations of Bengaluru Metro's sixth Tunnel Boring Machine (TBM) launched for the 600-metre distance from the Jayanagar Fire Station (South Ramp) to Dairy Circle.
Drilling is being done in connection with the Underground Corridor that figures in the Nagawara-Gottigere line. For the 13.92-km underground stretch between Dairy Circle and Nagawara, the work has been divided into four packages for speedy completion.
"The TBM which has been commissioned today is the second of Package One, the contract of which has been awarded to Afcons Infrastructure Limited. The second TBM has been set in motion following the completion of 70 metres by the first TBM from Vellara Junction to Langford station," said a senior official of the Bengaluru Metro Rail Corporation Limited (BMRCL).
He said that the TBM will take upto five months to reach Dairy Circle. "It will drill an average of 4 metres per day," he added. Nine TBMs will be carrying out tunnelling operations along the underground stretch, 3 of them would be Earth Pressure Balancing (EPB) machines while six would be slurry machines.
"The TBM on Friday was a slurry machine which ensures that the sludge removed after drilling is sent directly to a treatment plant, he said. In the case of the Earth Balancing Machine, a shaft needs to be created and the excavated earth needs to be transported back to the top," he said.
The five machines which are simultaneously drilling presently have completed a total of 1,350 metres. The fifth machine that began drilling on March 12 was BMRCL's first indigenously assembled TBM, using parts manufactured in Germany.
In its journey towards Langford Town, it has completed 70 metres out of its 650-metre stretch. TBM 'Avni' drilling from Shivajinagar to MG Road has completed 375 metres while Lavi boring along the same direction has completed 65 metres.
'Urja' and 'Vindhya' are both drilling from Cantonment to Shivajinagar with the former having completed 450 metres while the latter 380 metres. The deadline for completion of underground tunnelling is end of 2023.