Bengaluru: Namma Metro's Pink line tunnelling faces rough terrain, rock slows down TBM work
Tunnelling for Bengaluru's Pink Line metro faces delays as TBMs encounter slow progress due to extensive stone layers in the final phase. With 97% of the work completed, TBMs Tunga and Bhadra struggle to meet daily targets, raising doubts about the August deadline. Despite challenges, authorities aim to enhance Bengaluru's public transportation network with the Pink Line.
FollowTunnelling work for Bengaluru's Pink Line metro, connecting Kalena Agrahara to Nagwara, is hitting a snag as Tunnel Boring Machines (TBMs) encounter slow progress in the final phase. According to sources within the Bengaluru Metro Rail Corporation Limited (BMRCL), the presence of extensive stone layers is impeding the pace of work, casting doubt on the completion of the tunnel by the scheduled August deadline.
The Pink Line, spanning 21.26 kilometres overall, includes a 13.09-kilometre subway corridor. Currently, with 97% of the tunnel work completed, TBMs named Tunga and Bhadra are navigating the last stretch. Tunga, operating from K.J.Halli to Nagawara, has drilled 938 meters, while Bhadra, also along the same route, has dug 939 meters.
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TBMs typically move at a rate of 10-12 millimetres per minute with an inner circle diameter of 6.8 meters. However, when encountering rock layers, this pace slows significantly to 1-2 millimetres per minute, resulting in a daily traverse of 4-6 meters. Due to the obstruction posed by substantial stone layers, TBMs are struggling to meet the targeted daily progress.
Ideally, the tunnelling work should have concluded by August. However, with the current challenges faced by the TBMs, meeting the deadline seems increasingly unlikely. BMRCL officials acknowledge the potential delay in completing other associated works.
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The Pink Line's route, stretching from Gottigere to Nagawara, passes predominantly through commercial areas. Tunnel construction has been divided into four packages, with three already completed. Various TBMs, including Avani, Lavi, Urja, Vindhya, Rudra, Varada, and Vamika, have completed their respective segments. Additionally, construction of 12 stations along the tunnel and 6 on the elevated line is underway.
The hindrances encountered in the final phase of tunnelling underscore the challenges inherent in mega-infrastructure projects. Despite setbacks, authorities remain committed to ensuring the timely completion of the Pink Line, which promises to enhance Bengaluru's public transportation network and alleviate congestion in the bustling city.
