The Alaskan Way Viaduct was built in the 1950s, and decades of daily wear and tear have taken their toll on the concrete structure. While it was safe for everyday use, it also remains vulnerable to earthquakes.
The 2001 Nisqually quake damaged the structure and hastened plans for its replacement. WSDOT repaired and strengthened the viaduct, and conducted twice-yearly inspections for safety. Parts of the viaduct, however, remain built atop fill soil that could liquefy in an earthquake. A tunnel will provide a much safer roadway for people travelling along SR 99.
Replacing the aging seawall is another element of improving the Seattle waterfront's resiliency against earthquakes. Visit the Waterfront Seattle website for information on the seawall replacement project.