The world's biggest tunnelling machine broke 1000 feet under Seattle

Seattle built an enormous tunnelling machine to dig beneath its waterfront.Then Bertha stopped.And when a machine this large breaks underground beneath a major city, there is no convenient workshop waiting nearby.This Industrial Empires documentary follows the extraordinary story of Bertha—from its gigantic rotating cutterhead and underground support systems to the mechanical failure that brought progress to a halt.The solution required engineers to effectively perform major surgery on one of the world’s largest tunnelling machines while it remained buried beneath Seattle.How do you rescue a machine that was never designed to come back out?Subscribe for more extraordinary engineering stories:https://www.youtube.com/channel/UCars5Y4vh9u0lAFmK1LmJ_A?sub_confirmation=1#Bertha #SeattleTunnel #Engineering