The 1989 Loma Prieta earthquake destroyed the similarly designed Cypress Street Viaduct in Oakland , California with the loss of 42 lives . The 2001 Nisqually earthquake damaged the viaduct and its supporting Alaskan Way Seawall and required the Washington State Department of Transportation ( WSDOT ) to invest US$ 14.5 million in emergency repairs . Experts gave a 1-in-20 chance that the viaduct could be shut down by an earthquake within the following decade . After the Nisqually earthquake , the viaduct was closed twice a year for WSDOT to conduct inspections of the structure . Those inspections have discovered continuing settlement damage . In 2005 , a group of researchers and faculty from the University of Washington urged political officials to close the viaduct within a two-year timeframe
1989 Loma Prieta earthquake
1989 Loma Prieta earthquake
Alaskan Way Viaduct replacement tunnel