Latest Program News

  • Highway construction inside the tunnel moves north

    This week, Seattle Tunnel Partners shifted gears and moved its road-building operation north for the final 3,000 feet of lower roadway inside the SR 99 tunnel.

    Unlike the southbound (upper) roadway, which was built using concrete pours, the northbound (lower) roadway comes together one 22-ton panel at a time. The pre-made panels are trucked into the tunnel, lifted with a specialized crane and joined together to create a functioning highway.

    This new time-lapse video shows how the road comes together:

    STP installed the first 6,000 feet of lower roadway by hauling the panels from the south portal to a point roughly under Virginia Street and First Avenue. From there, they worked their way south, installing panels as they went. Following the recent completion of the upper roadway at the tunnel’s north end, crews can now deliver panels via the north portal and work south-to-north to finish the final 3,000 feet of lower roadway.

    There’s still a lot work ahead before the tunnel is ready for traffic. STP must complete installation and testing of all the operational and safety systems that will make the tunnel function. You can follow the work on our tunnel progress tracker.

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  • Looking forward to a busy 2018

    There’s a lot to be excited about as the Alaskan Way Viaduct Replacement Program enters 2018. We’re working toward several important construction milestones.

    Pushing toward tunnel completion

    STP made great progress last year. They finished tunneling, disassembled the tunneling machine and completed the southbound (upper) roadway inside the tunnel. Based on STP’s newest schedule (PDF), the tunnel could open to drivers as soon as this fall. Our goal is to safely open the tunnel to traffic as quickly as possible and begin removing the Alaskan Way Viaduct, but it’s too early to accurately predict a tunnel opening date. Safety and quality remain our top priorities, and will continue to guide all work on the program.

    A significant amount of work remains between now and tunnel opening. Crews must complete construction of the roadway within the tunnel, and finish installing many interconnected systems that will be required to operate the tunnel. They also must complete a series of thorough tests and certification by the Seattle Fire Department to ensure the systems are working properly. This includes testing approximately 5,000 individual components and nearly 90 tunnel systems. 

    As always, WSDOT will continue to closely monitor STP’s work. You can do the same at our construction tracking page.

    The road to tunnel opening

    As STP continues their work, construction of final ramp and highway connections to the tunnel is set to begin. The SR 99 Connections Project will build the final connections between the existing highway and the tunnel. Scarsella Bros., Inc. is the contractor for this work, which will be performed under a $22.6 million contract awarded by WSDOT last month.

    Scarsella will break ground soon and continue their work throughout this year. When the tunnel is ready to open, SR 99 through downtown Seattle will be closed to traffic for approximately three weeks. Ramps to and from SR 99 will also be affected during this work. The final connections to the tunnel can only be built after the viaduct has been closed because crews must demolish portions of the current roadway to realign SR 99. When these roadway connections are complete, drivers will begin using the new tunnel.

    We recognize that this temporary closure of SR 99 will affect the entire region. We’re also aware that the tunnel is one of many projects under construction in downtown Seattle. We will continue to coordinate construction activities with the City of Seattle, Port of Seattle and King County to minimize disruptions to the public. As we always do during major highway closures, we will coordinate with our partner agencies to spread the word, and help keep people and goods moving while crews complete their work.

    After the tunnel opens

    After the tunnel opens to drivers, we can begin the challenging task of demolishing the Alaskan Way Viaduct. The demolition contractor will also be responsible for decommissioning the Battery Street Tunnel and reconnecting surface streets across Aurora Avenue North. These three projects were combined under a single design-build contract to shave off approximately one year of cumulative construction time. 

    As we explained this summer, the contractor will determine how the viaduct will be demolished within parameters set in the contract. We plan to select a contractor in late spring, and will share the demolition plan and schedule after the contractor is chosen.

    We’re excited about the work that lies ahead in 2018. Stay tuned for new photos, videos and social media updates as we push toward tunnel opening.

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  • Looking back on a year of great progress

    Less than 12 months ago, the tunneling machine Bertha was assembling tunnel rings beneath the Belltown neighborhood in Seattle. The machine was 2,500 feet away from the finish line near Seattle Center, with an estimated arrival of June 2017.
     
    So much has been accomplished in the past year, highlighted by Bertha’s arrival in April. Today all the rings are built and the tunneling machine is entirely disassembled. Inside the tunnel, the southbound deck is 99 percent complete and the northbound deck stretches over 2,400 feet.
     
    The contractor crews from Seattle Tunnel Partners completed far too much work this year to capture in one video, but here is a year-end review:
     

    Other highlights from a successful 2017:


    A big thank you to everyone who tuned in this year as we reported on the progress being made to replace the Alaskan Way Viaduct. Stay with us for 2018 as we near completion of the tunnel!

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  • New virtual library will preserve Milepost 31’s exhibits

    Milepost 31, our award-winning information center in Pioneer Square, will be closing this Saturday. During the six years it was open, Milepost 31 welcomed nearly 80,000 visitors and was an important resource for people exploring the Pioneer Square neighborhood.

    Spots remain open for our final viewing platform tours! Looking for a free activity over Thanksgiving weekend? Take a tour on Saturday.

    If you don’t get a chance to visit the center this week, its exhibits on the history of the land that became Pioneer Square will live on beyond the physical venue’s closure. We have created a virtual library featuring 360-degree views of Milepost 31’s displays and videos: www.milepost31.com.

    Screen shot from milepost website showing view of exhibit

    A big thank you to the staff, volunteers, partners and attendees who have helped make Milepost 31 a success.

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