Built in the late 1950s and opened to traffic in 1957 ( as SR 17 ) , the Cypress Street Viaduct , a stretch of Interstate 880 , was a double-deck freeway section made of nonductile reinforced concrete that was constructed above and astride Cypress Street in Oakland . Roughly half of the land the Cypress Viaduct was built on was filled marshland , and half was somewhat more stable alluvium . Because of new highway structure design guidelines – the requirement of ductile construction elements – instituted following the 1971 San Fernando earthquake , a limited degree of earthquake reinforcement was retrofitted to the Cypress Viaduct in 1977 . The added elements were longitudinal restraints at transverse expansion joints in the box girder spans , but no studies were made of possible failure modes specific to the Cypress Viaduct . CalTrans has since received widespread criticism for not thoroughly studying the structure . When the earthquake hit , the shaking was amplified on the former marshland , and soil liquefaction occurred
1971 San Fernando earthquake
1971 San Fernando earthquake
1989 Loma Prieta earthquake