By December 6 , 2013 , Bertha had tunneled , or 11 % , of the total length of the tunnel , stopping about below ground between South Jackson Street and South Main Street . The machine 's progress was halted on that day by an unexpected impediment . After a month 's investigation , WSDOT announced that the machine 's cutting blades had encountered an , steel pipe , one of several well casings left over from a previous 2002 drilling project that had assessed groundwater conditions and soil stability in the area in case of another earthquake , such as the 2001 Nisqually earthquake , which led to a need for the replacing of the Alaskan Way Viaduct in the first place . Because the machine can not cut through metal , the pipe damaged several of Bertha 's cutting blades , necessitating blade replacement before the machine could proceed . The pipes ' locations were known to WSDOT and the agency thought they had been removed . It is unclear whether the state agency or one of its contractors is responsible for the left-behind pipes , as well as who was responsible for allowing the tunneling to proceed without their removal
2001 Nisqually earthquake
2001 Nisqually earthquake
Bertha (tunnel boring machine)