Bangalore Metro’s TBM Bhadra Records Breakthrough at Shadi Mahal

‘Tis the season of breakthroughs!

Tunnel Boring Machine S-840B (Bhadra) operated by ITD Cementation India on Friday recorded a tunnel breakthrough at Shadi Mahal TBM Retrieval Shaft on Bangalore Metro’s 21.386 km Pink Line (Reach 6).

This was TBM S-840B’s 2nd of 4 breakthroughs and ITD Cem’s 4th 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 commissioned from Venkateshpura Station in June 2021 and first traveled 822.99m south to Tannery Road through mixed-soil where it recorded a “hidden” breakthrough in July 2022.

The machine traveled another 209m for its 2nd drive through Tannery Road Station’s box and onwards to a dedicated TBM retrieval shaft where it showed its cutterhead for the first time in over 500 days.

Due to this section’s highly variable challenging soil profile, the machine was halted multiple times to plug 2 sinkholes with grout and change its damaged cutting discs at least 3 times. During these events, ITD’s other machine TBM Tunga (S-839B) which was commissioned an entire month after, surpassed Bhadra.

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.

Breakthrough Video

In the above video, which I highly recommend watching, starting at the 1:55:30 mark ITD has shared some excellent drone and ground views of all stations within their package. At the 2:26:00 mark, workers can be seen demolishing tunnel rings built by Tunga and Bhadra within Tannery Road’s station box.

With this development, Bhadra will now be dismantled and taken back to Venkateshpura for its third drive of 1172.16m northwards towards Kadugondanahalli. I’m expecting it to be commissioned by early February 2023.

Its sister machine TBM Tunga (S-839B), which arrived at Shadi Mahal Shaft in August, had started its third drive towards Kadugondanahalli in October-end.

As shared earlier this week during TBM Vamika’s breakthrough further south, BMRCL’s recent November newsletter indicates approximately 62.39% of tunneling work had been completed for Phase 2 (total scope: 21,041m) by October-end.

With this development, a total of 16 out of 26 breakthroughs have recorded: 5 on Package RT-01 by Afcons, 3 on RT-02 by L&T, 4 on RT-03 by L&T, and 4 on RT-04 by ITD Cementation. I’m expecting the next one to be recorded by TBM Lavi for the 1134m MG Road – Vellara section in mid-January 2023. That’ll be the 4th and final event to mark 100% tunneling completion for RT-02.

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– TMRG