The Alaskan Way Viaduct was closed on January 11 , 2019 , and was replaced with a downtown bored tunnel that opened on February 4 , 2019 . The replacement project was spurred by the 2001 Nisqually earthquake , which damaged the viaduct and left it vulnerable to further damage , as well as city plans to revitalize the Seattle waterfront . The $ 3 billion megaproject was mired in planning delays for several years before construction began in 2011 with the partial demolition of the viaduct . The tunnel was constructed using Bertha , the world 's largest tunnel boring machine at the time of its launch in 2013 , which had a two-year delay and was completed in 2017 . After the viaduct is demolished in 2019 , Alaskan Way will be expanded into a park promenade
2001 Nisqually earthquake
2001 Nisqually earthquake
Washington State Route 99