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  • SR 99 tunneling machine to resume digging in March 2015

    See video of Monday's press conference

    Today, Seattle Tunnel Partners, our design-build contractor for the tunnel project, released a new schedule that shows the SR 99 tunneling machine will resume digging by the end of March 2015.

    Construction will begin late next month on the pit STP will use to access and repair damage to the machine, which stopped tunneling in December. Building the pit (pdf 715 kb) is the first of several steps STP has laid out to resume tunneling:

    • Late May: Begin building the access pit’s underground walls.
    • Late July through September: Excavate the pit.
    • October: Remove the machine’s cutterhead and begin repairing damage to the seal system and main bearing.
    • February 2015: Test machine to ensure it is ready to tunnel beneath downtown.
    • Late March 2015: Resume tunneling.


    These construction activities will be addressed in accordance with the SR 99 tunnel contract. The updated construction timeline delays tunnel boring by up to 16 months, but STP hopes to recover as much as four months of schedule to meet the November 2016 tunnel opening date we established in our 2010 request for proposals. STP had proposed opening the tunnel in late 2015, 11 months earlier than our original requirement.

    STP has informed us that crews will replace the machine’s main bearing and install a more robust seal system, which could include strengthening the seals, installing redundant systems, and adding monitoring equipment. Additional details will be included in a plan to be submitted to us for review by June 16.

    The repair schedule will include additional time to accommodate potential improvements to the machine that STP or the machine’s manufacturer, Hitachi Zosen Corp., might choose to make after the cutterhead is removed and crews are able to perform a full inspection. We will work with our strategic technical advisory team, made up of international and national tunneling experts, as well as consultants, to review the plan.

    More than $750 million in continuing work
    We’re disappointed by this delay, but believe the schedule is moving in the right direction. We’re also focused on the bigger picture, which includes more than $750 million worth of work at the tunnel portals and elsewhere along the SR 99 corridor. That construction is not affected by the tunneling stoppage and continues full speed ahead.

    West of Seattle’s stadiums, crews are building the future connection between the tunnel and the new section of SR 99 that was completed in 2012 after the viaduct’s southern mile was demolished. Crews are also making progress on the south portal operations building, which will house lighting, ventilation, emergency systems and other vital components needed to operate the tunnel.

    Meanwhile, at the tunnel’s future north portal, crews are building the connection between the tunnel and Aurora Avenue North, the north portal operations building and the 80-foot-deep pit where the tunneling machine will emerge at the end of its journey beneath downtown.

    Work is also ongoing in Frederickson, Wash., where crews have manufactured 72 percent of the concrete segments that are pieced together to form the tunnel’s exterior walls.  

    Before and after images of our progress are available on Flickr, along with regularly updated photos of construction


    Previous updates 

    April 3, 2014 update - Setting the stage for Bertha's repairs

    March 13, 2014 update - Seattle Tunnel Partners submits repair plan, archaeological surveys underway

    Feb. 28, 2014 update - A week in review: Bertha repair plan, ERP’s 2014 report and a viaduct weekend closure reminder

    Feb. 27, 2014 update - How is an early or late tunnel opening addressed in the design-build contract?

    Feb. 25, 2014 update - Ground settlement near the viaduct is safe, expected

    Click here to see a full archive of progress updates

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  • New photo feature: Before and After

    We do our best to tell you about the progress we’re making as we work to replace the Alaskan Way Viaduct. But the best way to appreciate it is to see it in photographs.

    For example, it wasn’t too long ago that the viaduct was nearly twice as long as it is today. Then, in 2011, crews demolished the southern mile of the double-deck highway, replacing it with a new side-by-side section of SR 99 near the stadiums. Also new to the neighborhood is the South Atlantic Street overpass, which opened earlier this year. The new overpass dramatically shortens trips between the freeways and the Port of Seattle’s busiest freight terminal by allowing trucks and other traffic to bypass train blockages on South Atlantic Street. These images show the transformation.

    To help you see more of the progress we’re making, we’ve launched a new photo set on Flickr. The tunneling machine may not be moving forward at the moment, but other work is. And it’s a striking story in photos. Let us show you.

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  • SR 99 tunnel’s north portal taking shape near the Space Needle

    A few blocks northeast of the Space Needle, crews are building the north portal of the SR 99 tunnel. It’s a huge piece of the overall tunnel project, but it’s largely invisible to the thousands of people that pass by it every day.

    About the only place you can see the north portal taking shape is from the viewing deck of the Space Needle because most of the construction is underground, inside a pit that’s every bit as impressive as the launch pit where Bertha, the SR 99 … more

  • Lots to see inside the tunnel launch pit

    You can’t see much from the surface, but there’s a lot of work happening in the launch pit where tunneling started last summer. Last week, Seattle Tunnel Partners removed the giant steel frame that Bertha, the SR 99 tunneling machine, pushed against to start her drive into the tunnel. The frame is now on its way to be recycled.

    Work is also well underway to dismantle the temporary concrete tunnel rings Bertha installed to give her additional leverage at the start of her … more

  • Keeping the Alaskan Way Viaduct safe until the tunnel opens

    We're looking forward to opening the tunnel to traffic and demolishing the Alaskan Way Viaduct. It’s the reason we come to work each day. But until we take down the viaduct, it’s our job to protect it and keep it safely open to drivers.

    And so this weekend, as they do four times every year, WSDOT crews will inspect the viaduct. They’ll start by closing the structure to traffic on Saturday and Sunday. Then they’ll begin a methodical weekend of work measuring … more

  • Building a better transportation system

    The Washington State Department of Transportation is working to build a safer, more durable, effective transportation system for our citizens. All across the state – from Bellingham to Vancouver, Forks to Spokane – we manage hundreds of important transportation projects each year to upgrade or replace aging roads and bridges, increase capacity for carrying people and freight, and create more environmentally sustainable travel options for the public.

    You’ve been hearing … more

  • The beauty of barging

    On Nov. 23, crews started barging soil from the tunnel dig site to a disposal facility near Port Ludlow. Adding barges to the fleet of trucks hauling away soil has greatly improved the speed and efficiency of the tunneling operation.

    The reason for that is simple: Bertha is moving a lot of soil – soil that has to be taken away to make room for more soil. If crews removing it can't keep up with Bertha, the bin where the soil is stored gets full and the machine has to slow down. … more

  • Tunneling in Seattle started long before Bertha

    Seattleites were digging tunnels long before Bertha, the SR 99 tunneling machine, came along. Folks started transforming subterranean Seattle in 1894, with construction of a sewer tunnel not far from the SR 99 tunnel’s north portal construction site. Since then the city has seen – or not seen, as the case may be – construction of more than 40 miles worth of tunnels.

    Last month marked the 109th anniversary of the historic breakthrough on the Great Northern Tunnel, which … more

  • Happy Birthday, Bertha Knight Landes – you were one of a kind

    Saturday, Oct. 19, marks the 145th birthday of Bertha Knight Landes, after whom the SR 99 tunneling machine was named.

    Ms. Landes didn’t dig any tunnels, but there’s no question she broke ground. Elected mayor of Seattle in 1926, she was the first woman to lead a major American city. During her two years in office she battled bootleggers, cleaned up corruption in city government and put the city’s finances in order.

    She was active outside of politics, too, playing … more

  • Bertha breaks 200-foot mark

    Bertha, the SR 99 tunneling machine, has passed the 200-foot mark as she continues her dig toward the north end of downtown Seattle.

    By the end of her shift on Oct. 8, Bertha had traveled a total of 209 feet and the top of her cutterhead was about 20 feet below the surface. She averaged nearly 14 feet of digging per day over the past week.

    Bertha is still making her way through fill soil that crews have injected with grout to provide additional strength. She’ll pass into … more