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Perhaps you’ve heard of Bertha, the World’s Largest Tunnel Boring Machine or TBM? She’s currently working her way underneath Downtown Seattle, excavating the Alaska Way Bored Tunnel to replace the aging Alaska Way Viaduct. This $2 Billion megaproject is an incredible feat of engineering on so many levels. I was in Seattle in September for the Association of Engineering Geologists annual meeting, and was fortunate enough to attend a field trip to see the launch pit and Bertha before she began her tunnel drive. It was an unforgettable experience for this engineer! In this article I give an overview of the project and Bertha herself, discuss some of the geotechnical features, and share my photos and video. Check it out!