SR 99 tunneling machine - Bertha
These photos highlight the journey of Bertha, the world’s largest-diameter tunneling machine, which will dig the State Route 99 tunnel beneath downtown Seattle beginning in summer 2013. Manufactured in Japan, the five-story-tall machine arrived in Seattle in April 2013. The tunnel will open to traffic in 2016. Visit www.alaskanwayviaduct.org for more information.

Learn more about Bertha at her webpage or follow her on Twitter @BerthaDigsSR99.
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