Advisories/Updates

  • July 14 update: Bertha disassembly is halfway complete

    Seattle Tunnel Partners is now past the halfway point in disassembling the 8,000-ton tunneling machine Bertha. All of Bertha’s cutterhead is out of the disassembly pit and crews are working their way from top to bottom, cutting sections of the machine and lifting them by crane.

    Much of the machine’s trailing gear remains inside the tunnel, out of view of our time-lapse camera. Inside the tunnel, crews are cutting and hauling pieces of the trailing gear out of the tunnel via the south portal. This new time lapse video captures the work happening inside the tunnel.

    Work has progressed enough inside the disassembly pit to allow STP to use Bertha’s thrust rams to pull a large section of the trailing gear into the pit. Crews will now work from both outside and inside the tunnel to continue removing the trailing gear, which will help expedite work.

    Much of the conveyor system that moved extracted soils from the tunnel onto barges has also been removed. The photo below shows crews lifting the white over-water section of the conveyor last week.

    A crane removing a piece of the conveyor system

    While crews dismantle the machine, work continues on the road inside the tunnel. The photo below shows crews building the upper roadway inside the launch pit near the stadiums, where Bertha began her 9,270-foot tunneling journey underneath Seattle. You can monitor progress here.

    Concrete pours for the future roadway deck curing in the launch pit

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  • Visit us this summer at Seattle-area fairs and festivals

    This summer, members of our team will staff information booths at summer fairs/festivals. Stop by any of the fairs to make your own cardboard tunnel, see bits of Bertha and learn more about our work to replace the Alaskan Way Viaduct.

    Ballard SeafoodFest: Located in downtown Ballard. Admission is free.

    • Saturday, July 8: 11 a.m. to 7 p.m.
    • Sunday, July 9: 11 a.m. to 7 p.m.


    West Seattle Summer Fest: Located at The Junction. Admission is free.

    • Friday, July 14: 10 a.m. to 6 p.m.
    • Saturday, July 15: 10 a.m. to 6 p.m.
    • Sunday, July 16: 11 a.m. to 5 p.m.


    South Lake Union Block Party: Located at Denny Way & Westlake Avenue North. Admission is free.

    • Friday, August 11: 12 p.m. to 7 p.m.
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  • June 15 project update: New time-lapse video shows tunneling machine disassembly

    The inner-workings of the SR 99 tunneling machine Bertha are now fully visible from the camera above the pit where disassembly continues. The upper shield that surrounded Bertha is now gone – lifted and hauled away. Only a small portion of the cutterhead spokes remain. Next, Seattle Tunnel Partners plans to remove work-deck platforms, hydraulic systems, hyperbaric equipment and ring-building equipment. Remember, there’s 8,000 tons of machinery inside the disassembly pit and inside the north end of the tunnel. This brief time-lapse video shows what seven weeks of nearly non-stop work looks like as workers continue dismantling the five-story-tall tunneling machine.

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Program Spotlight

  • A full summer for Milepost 31 before closing in November

    Milepost 31 in Pioneer Square is gearing up for a busy summer of programming. Our information center continues to offer free public viewing platform tours to see the SR 99 tunnel’s south portal construction site. Bike tours have also resumed, which follow Bertha’s tunnel route and provide a unique way of understanding the historical and engineering aspects of this megaproject. You can sign up for tours online or in person at the center.

    Our First Thursday speaker series … more