On February 28 , 2001 , the Nisqually earthquake struck the Seattle area with strong shaking that caused signs of visible damage on the Alaskan Way Viaduct . The freeway was shut down for inspections , which found small cracks and other minor damage to non-structural elements that allowed it to reopen within 26 hours . Four more closures were ordered later in March and April due to pieces of concrete dropping onto the streets below , requiring emergency repairs to add steel rods to reinforce the columns . The first repairs were completed in November at a cost of $ 1.8 million and a set of new vehicle weight restrictions were implemented ; in total , $ 14.5 million was spent on various repairs due to earthquake damage . Annual inspections and continued monitoring found that the earthquake had caused settling of up to into the soil and weakened connections between the columns and highway decks . Additional investigations also found unrelated damage to the underlying seawall , which would need to be rebuilt to prevent a resulting collapse of the viaduct
Nisqually earthquake
2001 Nisqually earthquake
Washington State Route 99