Just an hour ago, TBM Krishna – a Herrenknecht EPBM Tunnel Boring Machine made a historic final breakthrough for Bangalore Metro’s Phase 1 project at the Majestic station’s South Shaft! This TBM was commissioned from Chickpet station in late December 2015 and took 9 months to complete the 747m north-bound tunnel.
Like its sister machine Kaveri, Krishna’s operation & maintenance was handled by a team of more than 50 personnel from the Robbins Company (and other subcontractors) who were brought in by the Coastal-TTS JV to get the much delayed tunneling drives for package UG-1 (Sampige Road – National College) completed. During its journey, the TBM encountered everything from soft soil to mixed face conditions of hard & granite rock which required frequent cutterhead interventions to keep the TBM advancing ahead.
Satellite view of the Majestic station’s southern shaft where the breakthrough took place:
With this breakthrough out of the way, the BMRCL can no longer entirely blame tunneling conditions for not meeting the ‘new’ April 2017 deadline like it recently did with the November 2016 one. Don’t hold your breath for the new one though. From here onward, it will take a minimum of 12 months to get the TBM out, cover up the shaft, clean up the tunnel, complete architectural detailing, lay track, install all critical electrical-signalling-telecommunication systems, conduct trials, obtain necessary approvals and commence commercial operations.
For more updates, check out the Bangalore section of The Metro Rail Guy!