All the TBMs excavating the Metro Tunnel’s 6.3 m-high, twin 9km tunnels have now finished their works after 20 months. Meg was the last TBM to hit the finish line and it arrived at the new Town Hall Station last week. Millie, Alice and Joan which are the other TBMs –– have arrived at the site during the past month.
Among them, the TBMs have lined the tunnels from South Yarra to Kensington with approx. 250,000 t of concrete, tunnelling a standard of 90 m per week. They excavated as deep as 40 m under the ground, crossing 12 m below the Yarra River, 7 m under the Burnley tunnel and just 1.5 m beneath the City Loop.
The great and giant TBMs are momently being dismantled. The ‘skin’ of each is going to remain underground to form part of the permanent tunnel lining, and the remaining TBM components are going to be assessed for potential reuse on some other tunnelling projects.
Of course, there is a lot of work to be done before the Metro Tunnel completion in 2025 – comprising more excvating works using roadheaders to finish the final section of tunnels alongside the platforms at Town Hall Station. Work is also being continuing on constructing the five new underground stations.