Breakthrough for metro TBMs at MG Road, Dairy Circle

Two tunnel-boring machines (TBMs) deployed on the underground metro line from Dairy Circle to Nagavara have achieved a breakthrough four days apart.

While TBM Vamika completed the tunnelling of 614 metres from the south ramp (near the Jayanagar Fire Station) to Dairy Circle on January 3, TBM Avni achieved the breakthrough on the 1,086-metre section from Shivajinagar to MG Road on January 6 (Thursday).

Vamika will continue its onward journey to the proposed Lakkasandra station while Avni will keep tunnelling onwards to Rashtriya Military School on Hosur Road.

Vamika will be following TBM Rudra, which completed the tunnelling of the parallel 614-metre line between the south ramp (near the Jayanagar Fire Station) and Dairy Circle on November 11 and is now headed towards the Lakkasandra station.

“TBM Avni encountered hard boulders for a length of around 280 metres, wherein tunnelling was extremely challenging and required very frequent interventions. This TBM will drive through the (MG Road) station area for further tunnelling to Rashtriya Military School,” the Bangalore Metro Rail Corporation Limited (BMRCL) said in a statement.

Avni’s pair, TBM Lavi, is tunnelling the parallel (north-bound) section and is likely to achieve a breakthrough soon after facing similar challenges. The TBM that completes one way of the tunnel will be redeployed on a new section. The machine will be dismantled and taken to the launching shaft of a new section where the entire TBM will be reassembled so that it can tunnel again.

TBM Urja, which completed the Cantonment-Shivajinagar section in September, has been redeployed to tunnel from Cantonment to Pottery Town station.

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