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LocalGoodbye Bertha!

May 1, 2017

Bertha is a huge tunneling machine. She started digging a two-mile tunnel under the Alaskan Way Viaduct on July 30, 2013 and finished on April 4, 2017. Now the work of completing the Highway 99 tunnel can begin.

The Highway 99 tunnel will replace the aging and dangerous Alaskan Way Viaduct. This double-deck Highway was built back in the 1950s to offer drivers an alternative north-south route to going through downtown Seattle. 110,000 cars now use this two-mile stretch daily.

However, in February 2001, a 6.8 magnitude earthquake caused the Viaduct to sink. Everyone agreed that the old, damaged roadway was dangerous, so in 2011 action began to build the world’s largest-diameter bored tunnel as a replacement for the Viaduct.

Bertha was specially built for the Highway 99 tunnel job by the Japanese company, Hitachi Zosen. It was designed to handle the soil conditions of the Seattle Waterfront. At first the tunneling went smoothly but in December of 2013, Bertha heated up. Tunneling stopped, and it took two years to repair the main bearing and seal system.

Now that Bertha is done, the completion of the roadwork will move fast because the Highway 99 tunnel is scheduled to be open by early 2019. The upper deck will move cars southbound while the lower deck will be for north bound drivers. A Seattle Times writer described the new tunnel as “a cathedral for cars.” Drivers going south will be able to see the 1,426 concrete rings supporting the tunnel and also a giant lighted arch.

Once the Highway 99 tunnel is complete, the Alaskan Way Viaduct will be demolished. A part of the Seattle scene will be gone forever.

Published May 2017

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