16 months after the Tunnel Boring Machine (TBM) Kaveri was commissioned from the Chickpet station in Bangalore, it finally made a breakthrough at the South-Shaft of the Majestic station!
The Coastal-TTS JV which is in charge of building the Green Line’s tunnels (contract UG1) had originally procured this EPBM TBM from German manufacturer Herrenknecht’s Chinese facility in 2012. After excavating & building the 432m up-line tunnel between KR Market station – Chickpet station in October 2014, TBM Kaveri was then redeployed to construct the 747m down-line tunnel between the Chickpet & Majestic stations. Temporary ring erection began in mid-February 2015 and the contractor then began placing permanent rings in early March 2015.
The TBM’s operation & maintenance was handled by a team of more than 50 personnel from the Robbins Company who were brought in to get the much delayed tunneling drives completed. During its 16 month journey from Chickpet, the TBM encountered everything from soft soil to mixed face conditions of hard & granite rock. Besides that, the crew had to also take into account the extremely precarious nature of old structures/buildings above and registered & illegal borewells along its route.
Satellite view of the Majestic station’s southern shaft where the breakthrough took place:
With the breakthrough out of the way, the down-line tunnels of the Green Line bored by TBM Margarita and TBM Kaveri are now ‘complete’, but it’ll be at least another 6 months before they can be used for sending trains down to Reach 4 (National College – Puttenahalli) for conducting trials – that’s if the BMRCL indeed plans to open that section as a standalone section like it did with Reach 2 (Magadi Road – Mysore Road) in 2015.
Now only 1 final breakthrough by TBM Krishna (Kaveri’s sister machine) is left to be made on the parallel up-line tunnel. Here’s the latest on that:
TBM Status as on 06.06.2016
Krishna:Tunneling bet C’pete &Majestic stn 573m (382 rings completed.166.5m (111 rings bal 2reach Majestic Stn
— Namma Metro CPRO (@uavasanthrao) June 6, 2016
For more updates, check out the Bangalore section of The Metro Rail Guy!