Program Spotlight

Latest updates on the Alaskan Way Viaduct Replacement Program

  • Bertha picking up speed

    It was a good first week back on the job for Bertha, the SR 99 tunneling machine.

    Bertha dug 64 feet between Sept. 23 and the end of the month, averaging about 11 feet of excavation per work day. Add that to the 24 feet she traveled prior to the monthlong stoppage in mining, and Bertha had traveled a total of 88 feet by the start of October.

    The end of September brought with it an important milestone: installation of the first permanent tunnel ring. Now that Bertha is building rings … more

  • Tunneling will close the SR 99 Alaskan Way Viaduct for one to two weeks, likely in early 2014

    More than 1,000 feet of soil separates Bertha from the spot where she’ll pass beneath the Alaskan Way Viaduct a few months from now. That gives drivers plenty of time to prepare for Bertha’s big crossing, which will require an extended around-the-clock closure of the viaduct.

    Crews will close the viaduct for one to two weeks to allow Bertha to tunnel beneath the structure (pdf 913 kb). The machine could reach the viaduct in early 2014, but a specific date for the … more

  • Remembering Bertha’s roots: two years of SR 99 tunnel construction in the books

    Time-lapse video highlights the hard work that led up to Bertha’s July 30 launch


    A lot can happen in two years. Just ask Bertha, the SR 99 tunneling machine.

    Two years ago this week, Bertha existed only on paper and her launch-pit site was little more than a field of dirt where the south end of the viaduct once stood. Our contractor, Seattle Tunnel Partners, had just received the go-ahead to complete final design and begin building the SR 99 tunnel.

    Then this … more

  • Desperately seeking soil: As we expected, Bertha is off to a slow (but good) start

    After slogging through 15 feet of concrete, Bertha gets a taste of the good stuff – but why did it take so long?

    Engineers depend on math. It is the thing that, more than any building material, gives shape to their designs. Want proof that what you’re building matches the design? Check the plans, do the math.

    But when it comes to tracking the progress of Bertha, the SR 99 tunneling machine, you can’t rely on an equation. Yes, we told you that Bertha would average 6 … more

  • Bertha begins: digging officially underway in Seattle

    This time, there were no crowds or fanfare. It was just Bertha, the world’s largest tunneling machine, finally getting the chance to do what she was built to do: dig.

    Bertha got her first taste of tunneling on July 30, officially starting the 2-mile journey beneath downtown. Early Tuesday afternoon, Bertha’s 5-story-tall cutterhead broke through the north wall of her 80-foot-deep launch pit. She’s expected to emerge in about 14 months near the intersection of Sixth … more

  • Bon voyage party for Bertha draws 5,000 people to SR 99 tunnel site

    Start with some sun, soil and celebration. Then add Bertha, the massive machine that will dig the SR 99 tunnel beneath downtown Seattle, and 5,000 of her closest friends. The result is a party big enough for the biggest tunnel-builder the world has ever seen.

    Thousands of people descended on the SR 99 tunnel launch pit on Saturday for a chance to see Bertha up-close before she starts tunneling later this month. Guests talked to project staff, learned about the project and walked around … more

  • Join Gov. Inslee for a public celebration at launch site July 20

    The power is on, the cutterhead is hooked up and two miles of Seattle soil await the teeth of Bertha, the world’s largest tunneling machine. Aside from running final tests, there’s only one thing left to do before the massive machine’s launch later this month: say goodbye.

    On July 20, Gov. Jay Inslee and the Washington State Department of Transportation will host a public celebration at Bertha’s launch site, west of CenturyLink Field, from 11:30 a.m. to 3 p.m. … more

  • New overpass set to open by the end of the year

    At the start of the year, it wasn’t much more than a few dozen steel beams and some columns sticking out of the ground. As the calendar turns to July 2013, the new South Atlantic Street overpass is taking shape at the southern edge of the State Route 99 tunnel construction site near the stadiums.

    The overpass will address a bottleneck near the entrance to the Port of Seattle’s Terminal 46, where trains crossing South Atlantic Street frequently block traffic. When it … more

  • Where will all that dirt go? Here’s the scoop

    Crews removed more than 86,000 cubic yards of soil during construction of the recently completed SR 99 tunnel launch pit. That may seem like a lot, but it’s nothing compared with the 850,000 cubic yards of soil that will be removed by Bertha, the SR 99 tunneling machine, as she digs her way beneath Seattle.

    How much is 850,000 cubic yards of soil? Put it this way: If, just for fun, you decided to pile it all on top of the turf at nearby CenturyLink Field, your pile would be … more

  • A big goodbye to Bertha’s big red crane

    By now, drivers on State Route 99 near the stadiums are used to seeing large cranes and machinery near the spot where Bertha will start tunneling this summer. A crane is a crane is a crane, right?

    Except when the crane in question is the Barnhart Modular Lift Tower, better known to most as the giant red crane that lowered many of Bertha’s 41 pieces into the pit where she’s getting ready to dig. Aside from having an impressively technical name, the modular lift tower, like … more