It looks like it’s bad news again for the in-progress Alaskan Way Viaduct replacement tunnel in Seattle, and for Bertha, the nickname for the world’s largest tunnel boring machine being used to create the underground highway. Bertha has been idle for much of 2014 due to a broken cutter system. And now the complex process to reach Bertha 60 feet below the surface has been halted. Recently a team of engineers discovered that the soil around Bertha is sinking as much as 1.4 inches in some places.
It was early December in Seattle when the world’s biggest-diameter tunnel boring machine, called Bertha, came to a stop underneath Seattle. It was plowing through the city’s underground as part of the two-mile project to bring SR 99 underground and replace the Alaskan Way Viaduct. Overnight, it seemed as if the whole of Seattle and beyond was curious: was it buried treasure from the gold rush days? Or bootlegger artifacts?