The Cypress Street Viaduct, often referred to as the Cypress Structure, was a 1.6 mile long, raised two-tier, multi-lane (four lanes per deck) freeway constructed of reinforced concrete that was originally part of the Nimitz Freeway (State Route 17, and later, Interstate 880) in Oakland, California.It replaced an earlier single-deck viaduct constructed in the 1930s as one of the approaches to the San Francisco–Oakland Bay Bridge. It was located along Cypress Street between 7th Street and Interstate 80 in the West Oakland neighborhood.It officially opened to traffic on June 11, 1957 and was in use until the 1989 Loma Prieta earthquake, when much of the upper tier collapsed onto the lower tier, killing 42 people.The Cypress Freeway Memorial Park is located in Oakland, at 14th Street and Mandela Parkway.ConstructionThe double-decked viaduct was initially designed in 1949 by the City of Oakland as a way to ease traffic on local streets leading to the Bay Bridge, such as Cypress Street . Built during the “white roads through black bedrooms” era, the route was partially chosen to displace perceived slums in West Oakland.The southernmost portion of the Cypress Street viaduct, which was designed as a central offramp structure exiting at Market Street between Fifth and Sixth Streets to the Eighth Street/Seventh Street on/off ramps, was the first phase of the overall project completed in October, 1955, by contractors Frederickson and Watson at a cost of $1.7 million. Construction on the second phase of the project, the double-decked viaduct portion, began in February, 1956 by contractors Grove, Wilson, Shepard and Kruge at a cost of $8.3 million, bringing the total cost of the viaduct project to $10 million. It was California's first double-decked freeway when it officially opened to traffic on June 11, 1957.
