Tunnels are dug on the Melbourne Metro Tunnel Project
What have Millie, Alice, Joan and Meg done, that no one else has done? They’ve dug their way to the new Town Hall Station in Melbourne and have broken through over the past month.
These ladies are the tunnel boring machines (TBMs) that have dug the 2 nine-km long rail tunnels under the existing City Loop. They have removed 600,000 cubic metres of rock and soil and lined the tunnel walls with 250,000 tonnes of curved concrete segments, creating the waterproof lining of the tunnels. They have dug through basalt rock, gravel, silt and clay; as dep as 40 metres below ground and up to 25 metres below; under roads, buildings and rivers, averaging 90 metres a week. TMB Alice wins the record for the best rate, managing to clock up 195 in one week.