Bangalore Metro’s TBM Tunga Makes Breakthrough at Tannery Station
Tunnel Boring Machine S-839 operated by ITD Cementation India last week recorded a “hidden” breakthrough at Tannery Road Station on Bangalore Metro’s 21.386 km Pink Line which will connect Nagawara – Kalena Agrahara through 18 stations.
Nicknamed Tunga, this was TBM S-839’s 1st of 4 breakthroughs and ITD Cem’s 1st of 8 breakthroughs planned for the 73.92 km Bangalore Metro Phase 2 project’s 4.591 km package RT-04 (Tannery Road – North Ramp).
This Herrenknecht mixed-shield EPB machine was launched in June 2021 and traveled 822.99m south from Venkateshpura to Tannery Road to build the northbound tunnel.
It’s currently tunneling through Tannery Road Station’s box and will tunnel another 209.585m towards a dedicated TBM retrieval shaft. As station excavation progresses, workers will dismantle the tunnel rings built by Tunga within the station box.
ITD’s scope of work involves building a combined total of 6.34 km twin tunnels, roughly 360 meter ramp at Nagawara, and four stations at Tannery Road, Venkateshpura, Kadugundanahalli (formerly Arabic College) and Nagawara.
Similar “hidden” TBM breakthroughs have been performed by Afcons Infrastructure in Chennai & Kolkata, and more locally at Dairy Circle Station – see details.
Per BMRCL’s June newsletter, TBM Bhadra (S-840) working on the southbound tunnel has completed 742 meters, and has roughly 80 meters to make its hidden breakthrough. Overall, Package RT-04’s progress stands at 24.74% completion (1575/6365m).
With this development, approximately 47.1% of tunneling work for Phase 2 (total scope: 20,855m) has been completed with 8 out of 26 breakthroughs recorded: 3 on Package RT-01 by Afcons, 2 on RT-02 by L&T, 2 on RT-03 by L&T, and 1 on RT-04 by ITD Cementation.
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