• 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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  • Overnight on-ramp and lane closures on SR 99/Aurora Avenue North set for Monday and Tuesday

    The on-ramp from Denny Way to northbound State Route 99/Aurora Avenue North will close on Monday, April 21, and Tuesday, April 22, from 11:30 p.m. to 5 a.m. Also during those hours, the right northbound lane of Aurora Avenue North will be closed between the Battery Street Tunnel and Valley Street.

    The closures will allow workers to improve street lighting along Aurora Avenue North. The work is part of the SR 99 tunnel’s north access project, which is building the connections between city streets and the future north portal of the SR 99 tunnel.

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Program Spotlight

  • 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