• Plan ahead for SR 99/Aurora Avenue North weekend closure Aug. 21-24 near South Lake Union

    Crews working for the Washington State Department of Transportation will close State Route 99/Aurora Avenue North between the south end of the Battery Street Tunnel and Valley Street beginning Friday night, Aug. 21 through Monday morning, Aug. 24.

    During the closure, crews will move the northbound and southbound lanes of SR 99 near Harrison Street onto a new structure to the west of the existing highway. Shifting traffic to these new lanes will provide space for ongoing construction of the SR 99 tunnel’s future north portal. SR 99 will remain two lanes in each direction in this area.  

    Stay tuned for more details. 

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  • July 22 project update: Yellow stacks installed at the north portal

    Earlier this month, the work zone to the west of Seattle’s stadiums got a bit brighter when Seattle Tunnel Partners installed four yellow ventilation stacks at the south operations building. This week it’s the north portal’s turn, as STP installs the north operations building’s ventilation stacks.
    The four yellow stacks were lifted into place Wednesday at the north portal site, which is located just east of the Gates Foundation. Manufactured in Longview, Wash. with American-made steel, the stacks will be part of the tunnel’s ventilation system. This post from April explains a bit more about the function of the two operations buildings.
    The color of the stacks was inspired by WSDOT’s yellow maintenance vehicles, some of which will be stored within the operations buildings. Like all aspects of the design, the color was developed with guidance from the Seattle Design Commission. 
    Image of north portal ventilation stacks
    Four tunnel ventilation stacks were installed Wednesday at the the tunnel's north portal, near the Space Needle.
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  • July 17 project update: Seattle Tunnel Partners submits new schedule for completing SR 99 Tunnel Project

    This week, Seattle Tunnel Partners began installing a new main bearing on the SR 99 tunneling machine. Installation of the machine’s most critical part comes on the heels of another vital piece of STP’s repair effort: an updated schedule that outlines the path for the machine’s launch beneath downtown and completion of the tunnel project.
    The SR 99 tunnel is now scheduled to open to drivers in spring 2018, according to a revised schedule (pdf 156 kb) STP submitted to the Washington State Department of Transportation. Machine repairs are scheduled to wrap up this fall. STP and manufacturer Hitachi Zosen will then perform an extended series of tests to ensure the machine is ready to complete the tunnel drive. 
    Tunneling is slated to resume in late November, with the machine emerging at the north end of downtown approximately one year later. The state is not able to verify the contractor’s schedule. 
    “The contractor’s schedule has changed, but the contract that governs their work remains the same,” said Todd Trepanier, WSDOT’s Alaskan Way Viaduct Replacement Program administrator. “The state is a paying customer in this transaction, and we’re intent on getting what we contracted for. We will continue to protect taxpayers and hold the contractor responsible for their work as they deliver this vital project.”
    Since lifting the front end of the machine from the ground in March, STP has fully assessed the disassembled machine parts and made significant repairs and enhancements (pdf 6.2 Mb). In addition to beginning installation of the main bearing, STP crews have installed portions of the new seal system that will protect the bearing. Modifications include the addition of reinforcing steel, new monitoring systems and upgrades to the soil-conditioning system to prevent clogging.  
    “Fully disassembling and assessing the machine was always the key to determining how long the repairs would take,” said Chris Dixon, Seattle Tunnel Partners project manager. “We want to reassemble the machine and resume tunneling as quickly as possible, but we also want to ensure the repairs are done right.”
    STP and Hitachi are responsible for the repair effort, including the schedule. While the machine has been under repair, STP has continued essential work at the future tunnel portals, including construction of ramp and highway connections, and the buildings that will house tunnel operations.  
    STP crews halted tunneling in December 2013 after the machine overheated. After an investigation, they discovered damage to the seal system and determined it needed to be replaced along with the main bearing. The cause of the damage has not been determined. Responsibility for costs associated with the delay will be determined through the process outlined in the tunnel contract.   
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Program Spotlight

  • 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