My first childhood entrance into San Francisco was from the East Bay in the winter of 1962. The grand welcome was the drive over the San Francisco-Oakland Bay Bridge. It’s the Interstate 80 link between San Francisco and points to the East.
Even though the Bay Bridge plays second fiddle to the more famous Golden Gate Bridge, the length, architecture, complexity, and history is every bit as interesting if not more so. The two bridges are very different, indeed. Total length of the Bay Bridge, not counting the approaches is 7.18 kilometres (4.46 miles). Meantime, the Golden Gate Bridge is 2.7 kilometres (1.7 miles) long, between the approaches.
Even though construction of the Golden Gate Bridge began earlier than that of the much longer Bay Bridge, it was the Bay Bridge that opened sooner. Construction of the Golden Gate, single span bridge began January 5, 1933 with the official opening on May 27, 1937. Work on the Bay Bridge started on July 8, 1933 with the official opening on November 12, 1936. To be fair, the logistics and difficulties were different for each of the fraternal twin bridges.
Unlike the single, long suspension span of the Golden Gate Bridge, the Bay Bridge is actually not one single bridge structure. It consists of twin double decker twin tower suspension bridges with a common anchorage support structure. To the east is the Yerba Buena Tunnel, the world’s largest diameter transportation tunnel at 23 metres (76′) wide, 18 metres (58′) tall, and 160 metres (540′) long. Originally, from Yerba Buena Island to Oakland existed a double balanced cantilever bridge, five truss bridges, plus two truss causeways.
I say “existed” because the original eastern span structures have been replaced with a contemporary style single tower, self-anchored suspension bridge over the shipping channel. This connects to a modern skyway/viaduct structure that crosses the shallows near Oakland.
The old truss bridges, causeways, and cantilever bridge section closed permanently this August 28th at 8PM. The brand new Eastern sections were opened this September 2nd at 10PM. So, in effect, this was the second of the grand openings for the Bay Bridge.
Before the first grand opening of the largest, most expensive bridge of its era, there were natural and political obstacles to overcome. There had been dreams of connecting Oakland with San Francisco with an over-the-bay bridge since at least the 1870s. But actual planning and work didn’t happen until the Reconstruction Finance Corporation agreed to buy bonds to be paid back later by crossing toll charges on the finished project.
Engineers and architects determined that a hybrid type of design would be necessary. The twin suspension bridge design of the Western span was needed for the deep portion of San Francisco Bay that was the route of large merchant and naval ships. On the other hand, a suspension design was deemed impractical for spanning the shallows and mud flats between Yerba Buena Island and Oakland. Due to the logistics and limitations of the early 20th Century, it was not feasible to build suspension bridge structures all the way, between the two cities.
The heavy construction required five phases. The east span was done first because it would be needed for transport of supplies and workers to the Yerba Buena and then to the suspension projects. The next phase saw the work on the tunnel. The western span came next. The suspension bridges presented the most difficult problems. The depth of the bay required very tall suspension towers. The connecting anchorage structure, by itself was taller than any of the buildings then found in San Francisco.
The next items were the eastern highway approaches on the Oakland side, access ramps and toll plaza. Then came the Transbay Terminal in San Francisco that included the control area for the four railroad lines that originally ran on the lower decks.
The Opening ceremony took place November 12, 1936. Former President Herbert Hoover was the guest of honor. California Governor Frank Merriam cut gold chains across the motor traffic lanes with an acetylene torch. The total costs, including the Transbay terminal and approaches were $77,000,000 in 1936 dollars.
Cars and light trucks travelled both directions on the upper decks, heavy trucks and railroad trains travelled both directions on the lower decks until 1962 when the bridge was reconfigured. After that date, westbound cars and trucks travelled the upper decks, eastbound cars and trucks took the lower decks. Train traffic had already been phased out by late 1958.
The East span suffered two major incidents in later years. February 11, 1968, a U.S. Navy trainer plane smashed into the cantilever span in a thick fog. Both officers were killed, the airplane dropped into the bay. There were no injuries nor deaths of motorists. Only one truss section required replacement.
Then during Game Three of the World Series, October 17, 1989, The Loma Prieta Earthquake struck. The 6.9 magnitude temblor caused a 50 foot section of the upper deck of the eastern truss bridge to collapse onto the lower deck. One fatality was reported. The bridge reopened about a month later.
The most recent projects included seismic retrofitting to replace portions of the original structural steel along the western span. The Eastern span total replacement has already been mentioned above.
The Blue Jay of Happiness is of the East span purist school. The original truss and cantilevered construction is his favorite. The ultra modern design will take some getting used to.