In April of 2017, Bertha, the massive tunnel-boring machine successfully completed digging a nearly 2 mile deep-bore tunnel under Seattle. The tunnel will carry traffic from the Alaskan Way Viaduct, which had been damaged and deemed seismically unsafe after an earthquake. The tunnel will be much less intrusive than the wall-like Viaduct structure, which cuts Seattle off from its waterfront, and the tunnel, new surface street, and transit will take care of the Viaduct’s 110,000 vehicles per day.Why did Seattle move the highway from above ground to below ground? What we’re the replacement options considered? How did Seattle settle on the deep bore tunnel, one of the most expensive options possible, as a replacement for the Viaduct? What was that process like?

Resources on this topic:

Bloomberg: “Stuck in Seattle”: https://www.bloomberg.com/graphics/2015-bertha/

Seattle Times: “Bertha’s woes grind on”:
http://www.seattletimes.com/seattle-news/berthas-woes-grind-on-more-delay-higher-cost-for-highway-99-tunnel/

Seattle Times: ‘8-lane highway’ on Seattle’s waterfront:
http://www.seattletimes.com/seattle-news/transportation/8-lane-highway-for-seattles-future-alaskan-way-challenged/

A special thanks to the Washington State Department of Transportation for the video and many wonderful photos of the project!

Other photo sources:
– Wikimedia Commons
– Flickr user Brad-514
– Flickr user Eric Fidler
– Flickr user Nic McPhee
– Flickr user Oran Viriyincy
– Flickr user Rene Schwietzke
– Flickr user SounderBruce
– Flickr user Stephen Bruce
– Flickr user tdlucas5000
– Flickr user Victor R Ruiz

More info on The Alaskan Way Viaduct: How Seattle chose the Bertha tunnel alternative

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