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The Alaskan Way Viaduct, an elevated section of State Route 99 in Seattle, was built in the 1950s, and decades of daily wear and tear have taken their toll on the structure. Because of the viaduct’s age and vulnerability to earthquakes, replacing it is critical to public safety.

The viaduct's central waterfront section is being replaced with a bored tunnel beneath downtown Seattle. The southern mile of the viaduct, near Seattle's port and stadiums, was replaced with a new roadway that has wider lanes and meets current earthquake standards.

For more information about the Alaskan Way Viaduct Replacement Program, visit

SR 99 Tunnel

SR 99 Tunnel

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