Bertha Tunnel Boring Machine Passes Major Landmark

SEATTLE, WA - Bertha the tunneling machine passed underneath the Battery Street Tunnel this week, putting the tunnel project within 1,600 feet of the finish line - that's about as far as three Space Needles stacked end to end.

The next milestone for Bertha, according to the Washington State Department of Transportation: Bertha will tunnel underneath the monorail support columns.

While thousands of drivers passed through the Battery Street Tunnel this week, Bertha was about 90 feet below the roadway. When Bertha passes below the monorail, it will also be about 90 feet deep. At this stage, Bertha is about 83 percent complete drilling the 9,270-foot tunnel.

Meanwhile, construction crews working behind Bertha have completed the roadway as far as Pike Place Market.

According to the latest schedule, Bertha will complete the tunnel by the end of May. The tunnel will be two miles long, and will eventually replace the Alaskan Way Viaduct along State Road 99. The entire project, including demolition of the viaduct and the tunnel, will cost about $3.1 billion.

Read more about the tunnel project on WSDOT's Bertha website.

Image via Washington State Department of Transportation