Washington State DOT Forges Ahead on SR 99 Tunnel Project with Arrival of World’s Largest Tunneling Machine

AASHTO Journal, 5 April 2013

The Washington State Department of Transportation this week announced the arrival of Bertha, the largest tunneling machine in the world that will soon begin digging the SR 99 tunnel under downtown Seattle. The new tunnel will replace the Alaskan Way Viaduct, which was deemed vulnerable to earthquakes.

The five-story-tall tunneling machine, known as Bertha, was built in Japan then taken apart into more than 40 pieces in order to make the journey to Seattle. Bertha officially arrived Tuesday and is expected to dock at Terminal 46 Friday, April 5. Once the 80-foot-deep launch pit is fully constructed, crews will piece Bertha back together and test her.

WSDOT has created a Twitter account for Bertha, which has been tweeting about her voyage and subsequent arrival in Seattle. “It’s been a long trip. I’m starving,” Bertha tweeted. “I don’t suppose those barges to the south of me could spare any dirt. You know, just a little snack.”

The SR 99 tunnel project is expected to cost more than $2 billion, with funding coming from several sources including federal, state, and local partners, money from tolls, and gas tax funds.

“Construction crews preparing for this machine’s arrival have accomplished an unbelievable amount of work over the past 18 months,” said WSDOT Secretary Lynn Peterson in a statement. “Thanks to their hard work, tunneling will begin on schedule.”

Additional information on the SR 99 Tunnel Project is available at AlaskanWayViaduct.org. ​​

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