Program Spotlight

Latest updates on the Alaskan Way Viaduct Replacement Program

  • Milepost 31 marks four years, 50,000 visitors

    For being Seattle’s “most boring” exhibit, Milepost 31 sure is popular. December marks the four-year anniversary of the information center, which blends information about the SR 99 Tunnel Project with the history of Seattle’s Pioneer Square neighborhood. In addition to recently welcoming the center’s 50,000th visitor, Milepost 31 staff have led hundreds of tours to see SR 99 tunnel construction, and hosted educational programs for school groups and youth … more

  • Exterior walls for operations buildings prioritize transparency

    As walls are installed at the north and south portal operations buildings in the coming weeks, drivers may be surprised by how little their view inside the buildings changes. The exterior walls of the large fan rooms will be made of glass, providing passersby with a glimpse of the everyday activities that will occur inside these important operation centers.

    The decision to use glass walls arose out of the guiding principles for the operations buildings: to reflect their function and … more

  • Understanding project insurance

    Protecting taxpayers is a top priority as we replace the Alaskan Way Viaduct. An important tool in this effort is our design-build contract with Seattle Tunnel Partners, which places a greater share of project risk on the contractor by requiring them to design and build the tunnel.

    Another protective measure is insurance, which the contract requires STP to have. Both STP and WSDOT are named on the project’s insurance policy, and both entities have the right to make insurance … more

  • Another underground connection at the south portal

    Future connections between the SR 99 tunnel and city streets are continuing to take shape at the south portal, even if they're only partially visible from the surface. Drivers passing overhead didn't know it, but Seattle Tunnel Partners recently demolished a temporary wall separating the future mainline section of the tunnel from the on-ramp that will one day allow travelers to access northbound SR 99 from the stadiums.

    The first photo shows the view from inside the cut-and-cover … more

  • SR 99 traffic shift highlights continued transformation at tunnel’s future north portal

    This weekend, crews will shift State Route 99/Aurora Avenue traffic onto new lanes through the construction zone at the SR 99 tunnel's future north portal. For drivers, a traffic shift is a change in the route one takes to get to work, events or a game. For road builders, a traffic shift is a way to mark the next step toward project completion.

    In this latest traffic shift, the progress is significant – 750 feet of new roadway that will be part of the permanent … 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

  • Making progress on the south end

    If you regularly drive SR 99 near the stadiums, you’ve probably noticed a lot of changes to the roadway during the past 16 months. For example, crews divided the northbound and southbound lanes into two separate roadways near South Atlantic Street to make room for more construction. And you’ve no doubt witnessed huge changes taking place in the work zone on either side of the road. Did you know that crews have been hard at work completing the southern portion of the SR 99 tunnel … more

  • Temporary tunnel access ramp helps Seattle Tunnel Partners rearrange work

    This week, crews working for Seattle Tunnel Partners inside the bored tunnel finished building the 400-foot-long ramp shown below. You might be wondering: Why is the ramp necessary? After all, crews completed more than a thousand feet of the tunnel without one. Turns out the ramp is part of STP’s plan to complete work now – while the SR 99 tunneling machine is being repaired – that was originally scheduled to be done after tunneling was complete. 

    Looking north … more

  • 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