BENGALURU: After tunnelling for 356 days, Bengaluru Metro’s Tunnel Boring Machine ‘Bhadra’ emerged at the ground level at 6.08pm on Thursday.
The breakthrough was meant to happen in the morning but was delayed twice, and finally took place by evening so that Deputy Chief Minister D K Shivakumar, who was in Delhi for a protest on Wednesday, could witness the event.
the challenges encountered, chief engineer of this underground stretch Dayanand Shetty said, “The uneven geology of having a mixture of hard rock and soil definitely played a role in delaying the tunnelling process. We have had a total of 106 interventions on the cutter head of the machine.”
Interventions refer to stoppages whenever the cutter discs suffer damage and need to be replaced. “We have 42 cutter discs carrying out the drilling job. Whenever the damage suffered crosses a certain limit, we need to stop the tunnelling, carry out repairs and restart them all over again.
Sometimes, it gets rectified in a day, but sometimes it takes even a week to be set right,” Shetty explained. In Bhadra’s case, drilling had to be stopped 106 times.
With no alert about an abandoned well inside a house along the route, work had to be stopped for a week as the machine caved in while passing through this area, he explained.
TBM BHADRA OMPLETES SECOND RUN
- Feb 8: Second leg breakthrough at KG Halli
- Tunnelled route: Venkateshpura to KG Halli
- 1185.8 m: Distance covered
- Feb 16, 2023: Begins tunnelling work
- 1066.8 metres: First leg tunnelled
- Contractor: ITD Ltd
ON THE PINK LINE
- Underground corridor of R6 line or Pink Line: 13.76km Dairy Circle (South Ramp) to Nagawara
- 20.99km: Total tunnelling length
- 91% Tunnelling completed
- 7 of 9 TBMs carried out job
- TBMs still drilling: ‘Bhadra’ and ‘Tunga’ along same route
- August 2024: Tunnelling deadline
- 12 UG corridor stations
- 75% Work on stations done
- 2025: Reach-6 line commissioning deadline
THIRD LEG TO START ON APRIL 7
- Venkateshpura to Shadi Mahal shaft
- To start from KG Halli on April 7
- Reach 6 line: 21.26km, Kalena Agrahara to Nagawara
