Bertha breaks on through to the other side of the Seattle viaduct project

By Tyson Fisher, Land Line staff writer | Thursday, April 06, 2017

Bertha, the giant tunneling machine used for State Route 99 in Seattle, has made a milestone breakthrough. Literally. The machine completed its 1.7-mile journey beneath Seattle on Tuesday, April 4, as part of the Alaskan Way Viaduct replacement project.

At 64 years to the day since the opening of the viaduct, Bertha pushed its way through a pit near Seattle Center on Tuesday. The viaduct project with Bertha will move SR 99 to a two-mile tunnel underneath Seattle, which is expected to be completed in early 2019.

Other elements of the project include:

  • A mile-long stretch of new highway that connects to the south entrance of the tunnel, near Seattle’s stadiums.
  • A new overpass at the south end of downtown that allows traffic to bypass train blockages near Seattle’s busiest port terminal.
  • Demolition of the viaduct’s downtown waterfront section.
  • A new Alaskan Way surface street along the waterfront that connects SR 99 to downtown.

The massive project is estimated to cost approximately $3.1 billion, funded by federal, state and local sources, according to the Washington State Department of Transportation. A large chunk of that funding comes from a 2005 state gas tax projected to contribute $1.5 billion toward the project. The second-largest funding source comes from the feds at $787.2 million dollars.

The project caught the nation’s attention in 2013 when Bertha broke down. The machine overheated and stalled after sand and grit penetrated some seals. Initially estimated to take four months, repairs took nearly two years. Bertha fired back up in late 2015. Credit for resuming the dig remains disputed, according to The Seattle Times.

According to a state DOT press release, crews will spend the next several days removing steel support braces that stand between Bertha and the interior of the 90-foot-deep disassembly pit. Once completed, Seattle Tunnel Partners, owners of the engineering marvel, will begin cutting the machine into pieces, some of which will be salvaged for recycling or future projects.

Bertha was designed and manufactured by Hitachi Zosen Sakai Works of Osaka, Japan, and it was completed in 2013. The machine, which cost $80 million, is 326 feet long and weighs 6,700 short tons. The cutter head diameter is 57.5 feet.

For more information about the Alaskan Way Viaduct replacement project, click here.

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