Portion of the collapsed Cypress Street Viaduct after the Loma Prieta Earthquake

The collapsed Cypress Street Viaduct seen from ground-level. Note detachment of upper vertical elements from lower and the lack of reinforcement at the point of detachment.

The Cypress Street Viaduct was a 2-kilometer long, raised two-tier, multi-lane (five lanes per deck) freeway constructed of reinforced concrete that was originally part of State Highway 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 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 Loma Prieta Earthquake occurred on October 17, 1989 when much of the upper tier collapsed onto the lower tier resulting in 42 fatalities. USGS photo from 1989 Loma Prieta earthquake. ... USGS photo from 1989 Loma Prieta earthquake. ... USGS public domain image. ... USGS public domain image. ... State Route 17 commonly known locally as Highway 17, is a freeway and expressway that runs between San Jose and Santa Cruz in the U.S. State of California . ... JUNCTION POSTMILE SR-17 SCL 0. ... Oakland, founded in 1852, is the eighth-largest city in California[1] and the county seat of Alameda County. ... Interstate 80 (abbreviated I-80) is the second-longest Interstate Highway in the United States. ... West Oakland is a large neighborhood in Oakland, California. ... June 11 is the 162nd day of the year in the Gregorian Calendar (163rd in leap years), with 203 days remaining. ... 1957 (MCMLVII) was a common year starting on Tuesday of the Gregorian calendar. ... The Loma Prieta earthquake occurred on Tuesday October 17, 1989, in the greater San Francisco Bay Area in California at 5:04 p. ... October 17 is the 290th day of the year (291st in leap years) in the Gregorian calendar. ... 1989 (MCMLXXXIX) was a common year starting on Sunday of the Gregorian calendar. ...

When in use, the upper tier was used by southbound traffic, and the lower tier was used by northbound traffic. Some sections of the Cypress Street Viaduct were largely supported by two columns on either side, but some sections were only supported beneath by a single supporting column. The design was unable to survive the earthquake because the upper portions of the exterior columns were not tied by reinforcing to the lower columns, and the columns were not sufficiently ringed to prevent bursting. At the time of its design such structures were not analysed as a whole, and it appears that large structure motion contributed to the collapse. It was built on filled land, which is highly susceptible to soil liquefaction during an earthquake and exhibits larger ground motion. Soil Liquefaction is the process by which saturated, unconsolidated soil or sand is converted into a suspension. ... An earthquake is a phenomenon that results from the sudden release of stored energy in the Earths crust that creates seismic waves. ...

The viaduct was torn down, and the corridor became known as Mandela Parkway (in honor of Nelson Mandela) with a landscaped median where the structure once stood. Interstate 880 was rerouted to loop around the area using a more conventional single level viaduct design. Mandela redirects here. ...

During construction of the new Cypress Freeway, a team of archaeologists made many interesting discoveries about the people who lived in West Oakland in the 19th century. [1] West Oakland is a neighborhood in Oakland, California. ...

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External links

• Cypress Street Viaduct
• Cypress Street Viaduct on Engineering.com
• Maps and aerial photos Coordinates: 37.821718° -122.287016°
  • Street map from Google Maps or Yahoo! Maps
  • Topographic map from TopoZone
  • Aerial image or topographic map from TerraServer-USA
  • Satellite image from Google Maps or Microsoft Virtual Earth