Contents tagged with viaduct

  • + How are you managing parking during construction?

    WSDOT and program partners meet regularly with a group of Pioneer Square and central waterfront stakeholders to identify and implement parking mitigation strategies. A plan to address short- and long-term parking concerns in these neighborhoods was completed in 2012. Example strategies include: adding temporary on-street parking spaces on Alaskan Way, implementing wayfinding signs and implementing a parking marketing program to let customers, visitors and the general public know that parking is available in Pioneer Square and on the waterfront during SR 99 tunnel construction.

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  • + Is viaduct replacement construction being coordinated with other nearby projects?

    WSDOT coordinates with partner agencies on nearly every aspect of the program including overall strategy and management, project schedules, construction and public involvement. Project coordination extends beyond the SR 99 viaduct replacement - coordination with the Elliott Bay Seawall Project, Mercer Corridor Project, Waterfront Seattle and many more are vital to keeping traffic moving and all projects on schedule.

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  • + When will the viaduct be demolished?

    In 2011, crews demolished the southern mile of the viaduct, which accounted for nearly half the structure. The remaining portion of the viaduct will be demolished after the SR 99 tunnel opens to traffic, and then a new Alaskan Way street will be built in its place. The new Alaskan Way, which will connect over the railroad tracks to Elliott and Western avenues and to SR 99 near the stadiums, will provide several east-west connections to downtown.

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  • + What will happen to the Battery Street Tunnel?

    The Battery Street Tunnel was constructed in the 1950s and has not been upgraded since. Its electrical and mechanical systems are difficult to maintain and do not meet modern safety requirements. WSDOT conducts regular safety inspections of the tunnel. It will be closed and filled in after the SR 99 tunnel opens to traffic in 2016.

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  • + Is most of the traffic using the viaduct going to downtown or through downtown?

    Before we demolished the southern mile of the viaduct in October 2011, it carried approximately 110,000 vehicles per day just south of the mid-town ramps. Of this amount, approximately 17,000 vehicles entered or exited downtown at Columbia and Seneca streets, and 33,000 exited or entered at Elliott and Western avenues toward Belltown, Uptown, and neighborhoods along the 15th Avenue and Elliott Avenue corridor. The remaining 60,000 vehicles continued north through the Battery Street Tunnel, either exiting in the South Lake Union/Queen Anne area or continuing further north.

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  • + Is the viaduct still a safe structure on which to drive?

    Routine safety inspections and maintenance keep the viaduct safe for public use. In 2008, crews strengthened four column footings where the viaduct had settled approximately five-and-a-half inches into the ground since the 2001 Nisqually earthquake. The column safety project limits settlement in this area of the viaduct and prevents further damage to the structure.

    We also installed a system designed to close the viaduct automatically in the event of a moderate to severe earthquake in the greater Seattle area. The automated closure system consists of traffic gates at all viaduct access points controlled by an earthquake detection system. If the earthquake monitoring system detects significant ground movement, it will simultaneously lower all nine traffic gates and safely close the viaduct in two minutes.

    In 2011, crews demolished nearly half of the vulnerable viaduct near Seattle’s port and stadiums. Drivers now use a construction bypass connected to new side-by-side bridges built to current safety standards.

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  • + Why is the viaduct a safety issue?

    The 1950s-era viaduct was already showing signs of age and deterioration before the 2001 Nisqually earthquake further weakened the structure, but the earthquake heightened the need for its replacement. The major risk facing the viaduct is its seismic vulnerability. The viaduct stands on fill soil bounded by the seawall. Marine organisms have slowly eaten away parts of the seawall and weakened it. In an earthquake, the fill soil is subject to liquefaction, where a shaking motion causes the soils to turn into a quicksand-like condition. Another major earthquake could collapse the seawall and liquefy the soil, damaging the viaduct beyond repair.

    View a simulation (YouTube) of what could happen to the viaduct if a strong earthquake were to shake the Puget Sound region (or watch a non-YouTube version - requires Windows Media Player). Visit the Elliott Bay Seawall Project website for information on the plans to replace the seawall.

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