In a first for the Namma Metro project, Tunnel Boring Machine (TBM) Urja drilled a distance of 27 meters on April 25. The machine is currently deployed between Cantonment and Pottery Town.
There are nine TBMs deployed to build a tunnel network for a distance of 14 km under the phase II of Namma Metro project. Usually, each TBM bore a distance of maximum of six meters in a day, but Urja outperformed them all by drilling a distance of 27 meters.
Anjum Parwez, MD, Bangalore Metro Rail Corporation Ltd. (BMRCL), said Urja’s performance is an achievement. “Favourable geographical conditions, continuous supervision, and skilled manpower who change rings are prominent factors for TBM drilling a distance of 27 meters in a single day. Building a tunnel network is challenging in Bengaluru. TBMs encounter various challenges. In some stretches, hard rock and loose soil create a lot of hurdles for the machines. Luckily, for Urja, there were conducive geographical conditions in its path.”
Urja was first deployed by the contractor to tunnel a distance of 855 meters from Cantonment to Shivajinagar. In July 2020, the machine was deployed at Cantonment and it achieved breakthrough at Shivajinagar a year later. After completing the task, the machine was deployed at Cantonment to drill towards Pottery Town.
Mr. Parwez said” “After Pottery Town, tunnelling towards Nagawara is likely to be a challenging task because of the water table.” The area from Pottery Town to Nagawara has a high density of buildings.
40% of work complete
According to the BMRCL, the nine TBMs that are deployed to build a tunnel network from Dairy Circle to Nagawara have completed 40 % of the task. Mr. Parwez said that TBMs are expected to complete the task by July 2023.
“Currently, all the nine TBMs are doing well. We are hoping that we are likely to complete the task of tunnelling for 28 km (parallel tunnels) by July 2023. Some TBMs have emerged at destined underground stations despite facing several hurdles. For example, two TBMs that burrowed a distance from Shivajinagar to M.G. Road, faced a tough task of boring hard rocks under Infantry Road. Clearing all hurdles, they emerged at M.G. Road station,” he explained.
In phase I, the BMRCL spent years building a tunnel for a distance of 8.8 km . There were many instances of TBM breaking down after facing hard rocks between Majestic and Sampige Road station and Victoria Hospital to Chickpet. Non-completion of tunnel work on time was one of the major factors for delay in commissioning commercial operations on the entire 42-km stretch metro line under phase I.
