By early 2016, the giant TBM "Bertha" in Seattle had resumed boring on the central waterfront section of the USD 3.1bn Alaskan Way Viaduct Replacement project, following repairs to the 57.5ft (17.53m) diameter machine. To prepare, Bertha has undergone an unusual, if not unique, experience for any TBM, not least the world's largest: she is being buried to commence boring. A 120ft- (36.5m-) deep shaft was constructed to reach the TBM, allowing its vital front section to be brought to the surface for repairs. Following the work, the TBM was reassembled, the cutterhead was turned and other no-load tests were completed. The last task is load testing to relaunch the TBM for its drive below the viaduct.
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