The project’s fifth TBM to launch set out yesterday from Plumstead portal to North Woolwich as part of the construction of a tunnel under the River Thames for London’s new rail link.
The 110m-long machine is scheduled to drill at an average rate of around 100m a week, installing precast concrete segments as rings to form the tunnel lining as it advances forwards.
Sophia is different to the tunnelling machines being used elsewhere on Crossrail. She is a slurry machine, equipped to deal with the chalk, flint and wet ground conditions of southeast London.
As part of the tunnelling process, the excavated soils will be pumped out as liquid slurry to a treatment plant at Plumstead (pictured below). The slurry will be separated into sand, gravel, water and chalk. The chalk will come out in ‘cakes’ or slabs of filtered chalk particles.
Crossrail chief executive Andrew Wolstenholme said: “The start of tunnelling in southeast London marks another milestone for Crossrail, a project that will transform public transport in and around the capital.”
Across the whole Crossrail project, eight tunnelling machines will construct 21km (13 miles) of twin tunnels under London. The whole Crossrail route will pass through 37 stations and run 118km (73 miles) from Maidenhead and Heathrow in the west, to Shenfield and Abbey Wood in the east.
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