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Cypress Street Viaduct

California first double-decker Freeway

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Above: Cypress Street viaduct photo taken in 1957 soon after opening this 1.3 mile twin-level viaduct connecting the Eastshore Freeway to the Nimitz Freeway via 5th & 6th streets through Downtown Oakland until 1959 when the addition 1.55 miles of the viaduct will be completed connecting the Cypress to the Nimitz Freeway

Photo Courtesy ofctlgo160_A.jpg (1645 bytes)

Above: Cypress Street viaduct October 17, 1989 after the 7.1 Loma Prieta earthquake. Notice how the upper-level has collapsed on the lower-level, the supports on the sides broke and split outward causing the upper-level to collapse

Photo courtesy of

 sipdrop.gif (1847 bytes)EBMUD Seismic Improvement Program

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Above: Photo taken soon after opening the Cypress Street viaduct looking north on the upper-deck. Notice: the old style sign bridge and the old style black & white signs

Photo Courtesy ofctlgo160_A.jpg (1645 bytes)

Above: Looking north on the upper-level of the Cypress Street viaduct. Notice how the roadway has a rippled or a wave like effect to it, in the distance you can see the roadway tilted to the right. The next section collapsed on the lower-deck.

Photo courtesy of

sipdrop.gif (1847 bytes)EBMUD Seismic Improvement Program

Cypress Street (Viaduct) Freeway

Offically opened to traffic on June 11, 1957 the Cypress Street (Viaduct) Freeway was the first double-decker freeway in the state. A 3 mile unit of the Eastshore Freeway built under three contracts totaling 15,250,000 million dollars. The Cypress had two levels the upper-level carried southbound traffic while the lower carried northbound traffic, with a roadway width of 52'. Parts of the Cypress was supported by a single base support while other parts had twin base supports. Like its cousin the Embarcadero Freeway, which also collapsed was located across the bay in San Francisco was opened four years later.

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Above: A map of the Cypress Street (Viaduct) Freeway you can see how it connects to the distribution structure to the Bay Bridge Approach and the northern section of the Eastshore Freeway US-40/SR-17.         Map courtsey of Gousha'

Cypress Street (Viaduct) Freeway collaspes 42 fatalities

The time was 5:04 pm on October 17, 1989. Sixty-two thousand baseball fans were preparing to watch the San Francisco Giants and Oakland A's in what was called the "Battle of the Bay", the World Series.  Many others fans watched the game from their homes. Announcers started the pre-game show when the earth started to shake Candlestick Park, which rocked and rolled Candlestick in a way it have never done before.  From Fresno to Eureka it was felt.  Roads split, on the Bay Bridge top level section a pin (bolt) snapped, sending a 50 foot section of the top section down on the lower deck, the Embarcadero Freeway in San Francisco was heavily damaged. Both the Cypress and the Embarcadero Freeways both were built on fill, and in the Cypress’ case, on an ancient streambed and not into solid bedrock. And when the quake hit not only did the earth shake back and forth but up and down too. The Cypress began to collapse when the braces holding the upper-level to the lower-level broke in two and then spilt outward sending the upper-level down on top of the lower-level with a force of approximately 2 million tons crushing auto's, trucks and buses along with their occupants. The collapse started in the northern sections of the freeway, and like a domino effect, each section began to collapse until most of the Cypress Viaduct looked like a nuclear bomb fell on it.  Soon after the earthquake then Governor Deukmejian appointed a board of inquiry to check all 12,000 bridges in the state and analyze what exactly happened to the Cypress Viaduct. In a report to the governor it was stated that the structure was designed to handle a quake three times stronger than the 1950 earthquakes standards required. Also in the report it stated that Caltrans should spend highway funds on preventing further bridge collapses instead of fixing problems after the fact.  Rebuilding the Cypress had it pitfalls of which one was where to build it.  One idea was to rebuild it in the same location as a single level viaduct at a cost of 306 million dollars compared to the 15,250.000 million dollars it took to build the viaduct in 1957. That plan was dropped. The other plan was to build the new Cypress Viaduct on a more northerly alignment through the Navel Supply Center and the Oakland Army Terminal. This plan was delayed by the military refusing to allow Caltrans engineers to conduct soil samples. This problem ended up pushing the completion date back to 2005. The final and completed alignment sent the Cypress Viaduct Freeway through an industrial area south of the military installations. The new freeway was completed in 1997 at a cost of 1.25 billion dollars.

Special thanks to Derek Law for his assistance in the completion of article above.

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Cypress Freeway

Photo Courtesy ofctlgo160_A.jpg (1645 bytes)

Embarcadero Freeway

Photo Courtesy of Derek Law

Cypress Freeway/ Embarcadero Freeway Sister Freeways which should have never been built.

Built on opposite sides of San Francisco Bay the double decker freeways of the Bay Area should have never been built. Because of the lack of proper right of way space for a single deck freeway the Cypress and Embarcadero were design as a two level structure. in the earthquake of October 1989 both freeways suffer major damage in the Cypress case most of the freeway collapse on top of the lower deck. On the San Francisco side the Em barcadero  Freeway suffer only minor damage but the cost of repairing this 28 year old structure, would involve too much structural retrofit and the cost to complete it would warrent keeping the Embarcadero Freeway. It was decided to tear down the Embarcadero and convert it into a city through-o- fare. In tearing down the Embarcadero Freeway in 1991, the Port of San Francisco Building once again had a full view of the bay

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Last updated on November 16th, 1999.

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