Nine tunnel boring machines going full tilt on 14-km Dairy Circle-Nagawara underground section
BENGALURU:
Tunnel Boring Machine (TBM) ‘Urja’ may not be aware of its record achievement, but on Wednesday the enormous machine completed drilling a distance of 855 metres from Cantonment station towards Shivajinagar.
The ‘breakthrough’ was witnessed by Chief Minister Basavaraj Bommai and senior BMRCL officials at around 10.15 am in Shivaji Nagar. This make Urja the first TBM in the city’s longest underground Metro corridor between Dairy Circle and Nagawara (14 km) of the Pink Line to complete its tunnelling assignment.
Covid-related delays
The machine, deployed by Larsen & Toubro (L&T), was the first to take up tunnelling work on the Pink Line in August 2020. The breakthrough was expected in nine months but took around 13 months because of Covid-related delays.
Explaining the geology of Urja’s section, a BMRCL release last year had said, “The expected geology in this tunnel section is about 250 metres of hard rock, 350 metres of mixed-ground conditions and about 255 metres of soil.”
TBM ‘Vindhya’, which is also tunnelling in the same direction, is expected to surface in a month’s time, while TBMs ‘Varada’ and ‘Rudra’ will complete their tasks by year-end.
Slow but steady
A total of nine TBMs are deployed on this section: four by L&T, three by Afcons and two by ITD Cementation. The giant borers complete around 2.5 to 5 metres per day, depending on the geological conditions. Of the four TBMs of L&T, ‘Avni’ and ‘Lavi’ are tunnelling between Rashtriya Military School and Shivajinagar, while ‘Urja’ and ‘Vindhya’ are tackling the Shivaji Nagar to Tannery Road underground stretch.
Afcons’ machines ‘Rudra’, ‘Vamika’ and ‘Varada’ are excavating the section between Dairy Circle and Langford Town, while ITD Cementation’s machines ‘Bhadra’ and ‘Tunda’ are boring between Tannery Road and Nagawara.
According to BMRCL, both the elevated and underground sections (Kalena Agrahara to Nagawara) will be operational by March 2025.
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