Summary:
It is also painstakingly slow, progressing only a few metres every week, and tunnelling under the Mithi is expected to continue right into October. Here, a part of the BKC Metro station and a 170-metre section of tunnel will be constructed right under the Mithi river, only a little over a kilometre from where it empties into the sea. One advantage of the NATM machines is that while other Tunnels Boring Machines or TBMs need to achieve a breakthrough at the farther end and be retrieved through a second shaft, NATM machines can be halted and reversed — as required for the BKC station’s third line. The ceiling of these tunnels will be 8.5 metres to 12.5 metres below the riverbed. Simultaneously, pre-drilled holes will be used to place steel pipes that will provide added support for the tunnelling machine as it advances..