Contents tagged with home

  • Viaduct closed March 24-25 for semiannual inspection

    3/15 12:30 p.m. update: Corrected a previous typo concerning hours of closure

    The Alaskan Way Viaduct will close the weekend of March 24–25 for the twice-yearly inspection WSDOT conducts to keep the aging roadway safe for everyday use. Both directions of State Route 99 will close between South Spokane Street and the north end of the Battery Street Tunnel.

    Closure details:

    • SR 99 closed between South Spokane Street and the north end of the Battery Street Tunnel.
    • Highway closed 6 a.m. - 6 p.m. Saturday, March 24 and 6 a.m. - 6 p.m. Sunday, March 25.

    Travelers will need to take an alternate route during the closure weekend and expect possible delays in the area.  If inspection work finishes early and the road can reopen before 6 p.m. Sunday, we will update this post and share via our Twitter account.

    These closures are conducted every March and October so engineers can closely inspect the viaduct. Take advantage of WSDOT’s travel tools and follow WSDOT Traffic on Twitter for updates on traffic in the Puget Sound region.

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    Order: 9.3

  • The disappearing signs of the SR 99 tunnel

    It’s been almost a year (April 4) since the tunneling machine Bertha broke through into the disassembly pit near Seattle Center. Today all visible signs of the machine and the large pits that bookended its 1.7-mile journey beneath downtown Seattle are gone.

    At the south end, the launch pit is now a smooth plane that will later become the roads and ramps connecting the tunnel to SODO, downtown and the Seattle waterfront:

    Camera view of the tunnel south portal with Safeo Field in distance at left

    At the tunnel's north end, the machine’s disassembly pit has been filled up to the surface, and now the final portion of the tunnel's north operations building (the building with the yellow ventilation stacks) is being built above it:

    The steel frame of the final part of the operations building being constructed

    Zooming back and you can clearly see where the closed block of Sixth Avenue North between Harrison Street (in the foreground) and Thomas Street (behind the operations building) will be rebuilt:

    North portal construction zone showing the disassembly pit fully covered

    Once completed, Sixth Avenue North will provide a north-south connection between Mercer Street and Denny Way, with an on-ramp to SR 99 southbound and the new tunnel. You can follow construction progress on our construction cameras page.

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    Order: 9.4

  • New construction camera will capture south portal's ramps

    We’ve installed a new time-lapse camera to capture work on the SR 99 Connections Project, which will finish building the ramps and roads that connect SR 99 to the new tunnel.

    Seattle Tunnel Partners has completed some of this work, and the remaining work will occur in their existing work zones at the tunnel portals (near the stadiums in the south and near Seattle Center in the north). A new contractor, Scarsella Brothers Inc., will complete this work.

    Our newest construction time-lapse camera, "SR 99 Connections South," captures a wide view of the tunnel’s south portal (click to see the camera):

    Screen capture of web camera view of tunnel's south portal, with orange circle around concrete tunnel entrance

    The circled structure above is where southbound traffic will exit the tunnel. The rendering below shows that same tunnel exit in relation to the completed south portal. 

    Computer rendering of ramp configuration when all construction is done

    SR 99 Connections will start work this month along East Frontage Road South and South Royal Brougham Road, just to the west of Safeco Field. Crews will be installing drainage, illumination and signals, as well as building roadway, curbs and sidewalks. Crews are scheduled to complete this work by the end of May.

    If you live or work near the north end or south end construction areas, you can join the SR 99 Connections construction email update list by sending an email to

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    Order: 9.6

  • Transforming Bertha's finish line

    The large pit north of Harrison Street that was the tunneling machine Bertha’s finish line has seen a series of dramatic transformations in the past few months. What was once a 90-foot-deep excavation to the west of SR 99/Aurora Avenue North will soon be entirely covered by a concrete lid, capping the future roadways and tunnel maintenance and systems corridors built within.

    In early January crews placed 10 girders across the pit. These girders, each 70 feet long and weighing 35 tons, will support the final section of the north portal operations building (the building with the four yellow ventilation stacks) that will be built atop the pit.

    This week, crews placed rebar and poured concrete to form a lid across the girders, burying the pit entirely from view.

    LEFT: The disassembly pit being built in 2014 (looking north)
    RIGHT: The disassembly pit on January 26, 2018 (looking north)


    Crews first began excavating the 450-feet-long and 90-feet-deep pit in 2013, in preparation for the completion of tunnel mining. Bertha broke through the pit's southern wall on April 4, 2017. Crews then used that space as the staging area for dismantling the 8,000-ton machine, a tremendous effort which they completed in August.

    Once the final piece of the machine was gone, the pit was ready for its second use: becoming part of the tunnel itself. Since August crews have been building walls and decks within the pit that will connect the bored tunnel’s roadways to the short section of cut-and-cover tunnel just to the north. Building these structures has slowly obscured the disassembly pit from view of our construction camera.

    In the coming weeks and months crews will begin constructing the final section of the operations building. They will also restore the block of Sixth Avenue North that has been used as a construction staging area for the north portal work.

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    Order: 9.7

  • #99closure feature: Drone footage inside the SR 99 tunnel

    Just a few days before the SR 99 tunneling machine started tunneling under the Alaskan Way Viaduct, the Washington State Department of Transportation flew a video-equipped drone through the SR 99 tunnel to show Seattle Tunnel Partners’ construction progress. There has been continued interest in seeing what has been built below ground and this video gives a glimpse of the tunnel as well as the nooks and crannies of the complex tunneling machine.

    On an average day, the tunnel is … more

  • The choreography of a concrete pour

    This week, at the south entrance to the bored tunnel, Seattle Tunnel Partners is pouring concrete for a section of the future southbound highway. On one hand, the pouring of concrete (also known as a "concrete placement”) is nothing extraordinary – it’s a common occurrence on a project that will use enough concrete to build nine football stadiums. But their frequency belies the complex choreography that goes into executing each pour successfully. Since concrete plays … more

  • Take a virtual tour of SR 99 tunnel construction

    Keeping the public informed about our work to replace the Alaskan Way Viaduct is an important part of what we do every day. Our goal is to give you as much access as possible to this amazing project, which is why we regularly post updates, photos and videos of our progress. We even offer walking tours from our information center, Milepost 31, to a viewing platform that overlooks the pit where tunneling began in summer 2013.

    Unfortunately, there’s one frequently received request … more

  • New narrated video explains Bertha repair work

    As reported elsewhere on our website, work to access and repair the SR 99 tunneling machine is coming along. We’ve heard from some people that Seattle Tunnel Partners’ repair plan is hard to picture. Enter STP’s Chris Dixon, who was nice enough to narrate a video that explains what crews are doing to resume tunneling by March 2015. Watch it on YouTube or download a WMV file.

    Other resources 

    Seattle Tunnel Partners repair work plan (pdf 4.8 Mb) … more

  • What we’re doing to keep traffic moving during the four-day SR 99 closure

    We’ve been asking you to do your part to reduce congestion when SR 99 closes for four days starting Friday night, Aug. 22. That includes things like changing your commute habits and choosing an alternate way to get around.

    But what are we, the agencies tasked with keeping traffic moving during this closure, doing to help? Quite a bit, actually. Here’s a roundup of some of the steps we’re taking to help you and your fellow commuters through the closure.

    Washington … more

  • Traffic shift underway on State Route 99 near the stadiums

    Less than three years ago, crews demolished the southern mile of the Alaskan Way Viaduct. When they did, they shifted traffic onto a new section of State Route 99 south of downtown Seattle.

    Much of that new section of SR 99 is permanent, but the piece west of the stadiums is temporary. This curving stretch of road takes drivers around the SR 99 tunnel construction site and connects to the remaining section of the viaduct near South King Street. It’s nothing fancy, but it’s … more