Helen bores through city at quick pace

The two Tunnel Boring Machines (TBM) — named Helen and Margarita — deployed by the Bengaluru Metro Rail Corporation Limited (BMRCL) have achieved considerable progress in the underground section of the Metro's East-West corridor. The machines have already drilled through a 4.8 km-stretch.
“By the third week of February, TBM Helen would reach the civil and session court area in Majestic. It would then proceed to the next underground station at the Vidhana Soudha and further till Minsk Square,” said the BMRCL spokesperson B.L. Yashwanth Chavan.

Both Helen and Margarita are boring the earth in a parallel manner, but the Helen is little ahead as it was put to work one month earlier. Once the two reach the Minsk Square, they would be put to drilling towards the west. The tunnelling is being executed by the CEC-Soma-CICI joint consortium, which will construct four underground stations with ramps as well. The North-South underground work has been entrusted to TTS and Coastal, and two more TBMs will be deployed by the firms for boring machines for boring four kilometer stretch with three stations and ramps. Apart from TBMs, three earth pressure balanced machines from Italy and two from China have been ordered, he added.

As the underground terrain is mostly rocky, the BMRCL has resorted to mild blasting. Mr Chavan said the corporation is ensuring that no damages happen to the surrounding structures. The work has been going on at the expected speed and has not faced any glitches, he said. Mr Chavan also said that the BMRCL has been chalking out guidelines to allow public and researchers to the tunnel boring area where work is in progress. The guidelines are being drafted, with the Delhi Metro Rail Corporation guidelines as a standard, with minor changes suitable to the local condition.