Program Spotlight

Latest updates on the Alaskan Way Viaduct Replacement Program

  • Face time with Bertha: last day above ground for massive tunneling cutterhead

    Suspended from a towering crane at the south end of downtown Seattle, the five-story-tall face of Bertha, the world’s largest tunneling machine, spent its last day above ground looking squarely at the old viaduct it was built to replace. Next stop: the 80-foot-deep launch pit where tunneling will start this summer.

    Crews working with the Washington State Department of Transportation lowered Bertha’s 838-ton cutterhead into the launch pit today, ending eight weeks of heavy … more

  • Launch pit complete, ready for Bertha

    Last spring, a field of unturned dirt marked the spot where Bertha will begin digging the two-mile State Route 99 tunnel beneath downtown Seattle. One year and 86,000 cubic yards of soil later, it’s a pit fit for the world’s largest tunneling machine.

    Crews finished building Bertha’s 80-foot-deep launch pit on Sunday after nearly a year spent building its underground walls, removing soil and building the infrastructure needed to support the nearly 7,000-ton machine. Its … more

  • Bertha's trailing gear first into the pit

    Last week, crews used a massive red crane to begin lowering the first large pieces of Bertha, the SR 99 tunneling machine, into the 80-foot-deep pit (pdf 485 kb) where she’ll start tunneling this summer. First up: the trailing gear, which will serve as Bertha's support system during tunneling by providing her with all of the equipment and materials she'll need to tunnel beneath downtown. The trailing gear accounts for much of the 326-foot-long machine's total … more

  • Into the pit: assembly of Bertha set to begin

    This week, crews will use a massive red crane to lower the first piece of Bertha, the SR 99 tunneling machine, into the 80-foot-deep pit (pdf 485 kb) where she’ll start tunneling this summer. Reassembling Bertha’s 41 pieces and testing the completed machine will take two to three months.

    Crews from Hitachi Zosen, Bertha’s manufacturer, will assist throughout the process. Bertha won’t officially become the property of Seattle Tunnel Partners, WSDOT’s … more

  • Bertha arrived in Seattle on April 2

    Sixty years ago this week, Seattleites welcomed the State Route 99 Alaskan Way Viaduct to the city’s downtown waterfront. On Tuesday, April 2, the waterfront again welcomed a hulking guest: Bertha, the five-story-tall tunneling machine that will clear the way to the viaduct’s removal in 2016.

    The ship carrying the machine that will dig the SR 99 tunnel beneath downtown Seattle entered Elliott Bay on Tuesday, April 2, after a two-week journey from the manufacturing plant in … more

  • Get ready, Seattle – Bertha’s on her way

    The journey started today with a single ship. It will end about two weeks and 5,000 miles later in the waters of Elliott Bay, with the much-anticipated arrival of Bertha, the massive machine that will dig the SR 99 tunnel beneath downtown Seattle.

    The five-story-tall machine left Osaka, Japan today aboard the Jumbo Fairpartner, the 475-foot-long vessel that will carry it across the Pacific Ocean. If the weather cooperates, the $80 million machine – which is owned by Seattle Tunnel … more

  • The unusual (but successful) path to replacing the viaduct’s southern mile

    At first glance, the curvy temporary stretch of State Route 99 that opened last fall to the west of Seattle’s stadiums seems like an unusual path for a highway to take. Certainly it’s not the straightest line between two points. But viewed in a broader context – keeping the highway open during SR 99 tunnel construction – it’s most certainly the right path. It saves everyone in the long run by maintaining a vital route to and through downtown Seattle as we … more

  • SR 99 tunneling machine problem nearly fixed

    Last month we reported that Bertha, the machine that will dig the SR 99 tunnel, was in the midst of an extensive testing program at the manufacturing plant in Japan. During testing crews discovered a problem with Bertha’s main-drive unit, which rotates the cutterhead at the front of the machine. She has since been partially disassembled so engineers could take a closer look at the issue.

    The diagnosis? Bertha’s going to be just fine.

    In fact, further examination of her … more

  • Uncover the launch pit's past Thursday at Milepost 31

    Before Bertha's launch pit was a launch pit, it was home to the south-end of the viaduct. And before that? Well, more than a century ago it was a neighborhood. Our team of archaeologists  uncovered a lot of cool stuff there in spring 2010 as we prepared to replace the viaduct's southern mile.

    Sometime around 1905, the neighborhood was abandoned, filled with dirt and turned into a rail yard. Fortunately, archaeologists knew that pieces of the area's history remained, … more

  • Testing of the SR 99 tunneling machine continues in Japan

    Before a professional athlete joins a new team, he has to pass a physical.

    Same goes for Bertha, the world’s largest-diameter tunneling machine. She doesn’t play a sport, of course, but digging a two-mile-long tunnel beneath downtown Seattle requires just the right combination of speed, skill and body control – all hallmarks of a world-class athlete. Which is why Bertha’s manufacturer, Japanese firm Hitachi Zosen Corporation, is putting her through the wringer as … more