Contents tagged with winter-closure

  • + What will WSDOT do to keep traffic moving during the closure?

    We will work with the Seattle Department of Transportation, King County, the Port of Seattle, Seattle Center and the stadiums to keep traffic moving during the closure. Alternate routes will be available. We will have WSDOT Incident Response Teams available to help clear blocking incidents or stalls. WSDOT, in partnership with King County Metro and the City of Seattle, recognized the potential effects of traffic closures during viaduct replacement construction and invested $125 million in projects designed to keep traffic moving. These investments include:


    • Phase 2 of the SR 519 project – a new I-5/I-90 westbound off-ramp to South Atlantic Street/Edgar Martinez Drive South which improved access to the waterfront and Port of Seattle.


    • $32 million to fund additional bus service with 41 new bus trips on key routes connecting downtown Seattle to West Seattle, White Center and Burien and strategies to encourage use of transit, carpools and vanpools.



  • + How will you protect buildings and other structures above the tunnel route?

    While we do not anticipate significant levels of settlement, as a precaution, we are implementing a comprehensive program to monitor and mitigate any effects of tunneling. As the tunneling machine pushes forward through the earth, crews will measure the soil it removes while also tracking any ground movement above its path.

    Buildings, utilities and streets located above and near the tunnel route will be monitored before, during and after construction. Each building will be surveyed prior to construction to document its interior and exterior condition. Monitors installed on the buildings by our crews will be checked against data from before construction, as well as data from monitors installed outside the monitoring area (pdf 2.9 Mb). If damage does occur to buildings, utilities or streets as a result of tunnel construction, we will be responsible for costs associated with repairs.


  • + How do you know it’s safe to tunnel beneath the viaduct?

    Our team has extensive experience tunneling in dense urban areas. Some of our crew members successfully built a nearly 40-foot diameter tunnel six feet beneath the famed La Sagrada Familia cathedral in Barcelona. The mitigation techniques that were used successfully during that project, including building angled walls beneath the structure’s foundation, are being used during SR 99 tunnel construction. Sound Transit has successfully tunneled through similar ground conditions and beneath a number of major roadways in the area, including I-5 and SR 520.


  • + Are you doing anything to protect the viaduct from settlement?

    Like most other structures, the viaduct was designed to withstand some settlement. We have taken a number of steps  (pdf 913 kb) to reinforce the viaduct and strengthen the soil beneath it. In 2012, crews installed angled underground walls around the viaduct’s footings to create a barrier between the machine and the structure. They also wrapped portions of the viaduct in carbon fiber to provide additional strength.


  • + How long will the closure last?

    The closure will start on a Friday following the evening commute and remain closed for one to two weeks. Tunneling crews will work around the clock to complete this portion of the tunnel drive and reopen the viaduct as quickly as possible.


  • + When will the viaduct be closed?

    Seattle Tunnel Partners, our contractor for the tunnel project, is developing a plan to address an issue with the machine’s seal system that halted tunneling in December 2013. The closure will occur after tunneling resumes. We will provide notice in advance and conduct extensive outreach to help travelers prepare.


  • + Why is it necessary to close the viaduct while the machine passes beneath?

    Keeping SR 99 open to traffic while we replace the viaduct is a top priority. Temporarily removing traffic from the viaduct while we tunnel beneath it will enable crews to monitor the structure more closely and act quickly to mitigate any settlement that may occur during this section of the tunnel drive. The short-term inconvenience of closing the viaduct will help us preserve it until we shift SR 99 traffic to the tunnel.


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