Program Spotlight

Latest updates on the Alaskan Way Viaduct Replacement Program

  • Paving the way to the SR 99 tunnel

    Crews working for Seattle Tunnel Partners have reached a concrete milestone at the SR 99 tunnel’s south portal.

    As shown in the aerial photo below, crews are building the cut-and-cover section of the tunnel in SODO, just west of Seattle’s stadiums. Earlier this month, they successfully poured the final sections of northbound mainline roadway concrete for this 1,500-foot-long stretch of the future highway. 

    Sections of cut-and-cover tunnel at both portals will … more

  • Tunnel’s two nerve centers taking shape

    State-of-the-art systems will be the key to maximizing safety and efficiency inside the SR 99 tunnel. Lighting and intelligent transportation systems (video cameras, traffic counters, variable message signs, etc.) will help ensure smooth traffic flow, while the ventilation, drainage and fire-suppression systems will help the tunnel meet the highest safety standards. To manage these systems, we’ll need nerve centers at each end of the tunnel. While they’re hard to see now, those … more

  • A look inside the new-look SR 99 tunnel

    Not long ago, you might have been able to fit a five-story building inside the cavernous circumference of the SR 99 tunnel. Not anymore. From the south end of the tunnel to the back end of Bertha, the SR 99 tunneling machine, crews have filled the tunnel with long stretches of walls and roadway sections of the future underground highway. The series of photos below shows just how much the landscape inside the tunnel has changed. 


    In the first photo, you are looking … more

  • A tunneling breakthrough near the stadiums

    Seattle Tunnel Partners is preparing for Bertha to break through the southern wall of the SR 99 tunnel access pit, but another, lesser known tunneling breakthrough has already occurred approximately 2,000 feet south of the pit. Earlier this month, crews demolished the temporary wall separating two sections of cut-and-cover tunnel under construction to the west of the stadiums. A cut-and-cover tunnel is just what it sounds like – dig a trench, then build a floor, walls and a … more

  • New time-lapse video highlights crane construction

    Crews have spent the past several months assembling the massive red crane that will lift Bertha to the surface for repairs. As STP prepares to move the machine into the pit, crane crews are also making final preparations. We put together a new time-lapse video to illustrate how the crane came to be. This post explains the assembly process in more detail. Don’t forget about our time-lapse cameras, which will give you a good view of STP’s work to repair Bertha. … more

  • Information for residents and businesses in Pioneer Square

    Recently, our team detected approximately one inch of ground settlement near the pit Seattle Tunnel Partners is building to access and repair the SR 99 tunneling machine. Settlement was also detected on the Alaskan Way Viaduct and some of the buildings that we are monitoring; the amount of settlement lessens in the surrounding area. Our experts are still analyzing data and conducting daily inspections of the viaduct, but the initial settlement we reported publically on Dec. 5 has since … more

  • New pavement and walls add shape to the tunnel’s future north portal

    At the construction site for the SR 99 tunnel’s north portal, imagining the future is getting easier. While it all looks like one project, north portal construction is comprised of two separate contracts. Roughly everything south of the tunnel entrance near Harrison Street is part of the main tunnel contract being completed by Seattle Tunnel Partners. North of the tunnel entrance, crews working for Atkinson Construction are building the lanes and ramps  that will connect … more

  • Heavy lifting with some very big cranes

    Since SR 99 tunnel construction started, big cranes have become a familiar sight on the west side of the Alaskan Way Viaduct. Recently, two new cranes have risen up, and they are like redwoods in a forest of pine trees. The “little” crane can lift up to 300 metric tons and stands 180 feet high. Its big brother can lift up to 600 metric tons and tops out at 236 feet high. That’s more than four times the height of the viaduct, or about the same height as the clock tower … more

  • Bertha soapbox car on display now at Milepost 31

    She’s like Bertha, but faster. Much, much faster.

    Meet “Bertha’s Last Stand,” runner-up at the 2014 Red Bull Soapbox Race in Seattle. Though not affiliated with or supported by WSDOT, a group of soapbox racers from Machias, Washington were so inspired by Bertha that they designed and built their own soapbox tunneling machine to drill through the competition. One of 36 teams that built and raced homemade cars through Seattle’s Pioneer Square neighborhood, … 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