The Incredible Span

By now, you should know that there are two bridges in San Francisco: the iconic Golden Gate Bridge, and the less famous, more attractive, Bay Bridge. I drive across the latter everyday to get to work and I’ve grown quite attached to it.

my photo from Nov 2010

In the 1800’s, there lived a crazy San Franciscan man named Joshua Abraham Norton who called himself the The Emperor of the United States. In 1872, Emperor Norton demanded that a bridge be built from Oakland to San Francisco. Nobody listened to him, because he was crazy. But fifty years later, the people realized that Norton’s bridge would actually be a useful addition to the area. In 1936, the Bay Bridge was completed and President Herbert Hoover called it “the greatest bridge ever erected by the human race.” The bridge is a double-decker with inbound traffic above the outbound. It’s 8.4 miles long, including the brief hop onto Yerba Buena Island. I actually found the SF Chronicle article from opening day 1936, if you’d like to read it [warning: pdf].

photo courtesy of Ingrid Taylar

In 1989, there was a huge earthquake in San Francisco (you know, the “world series earthquake”) and the Bay Bridge was seriously damaged. Part of the upper deck collapsed and one person died. An investigation revealed that the bridge was seismically unsound and needed to be rebuilt immediately. Plans to build a new bridge were finally set into motion in 2004, and are still in progress today. In other words, everyday that the old bridge is still in use is one more day that drivers’ lives are at risk. Encouraging, right?

photo courtesy of The Twisted Genius

The construction started with seismic retrofitting of all the existing trusses; an effort to make the bridge more safe until the new bridge is finished. The project is broken up into 5 segments, each with its own deadline. The entire new bridge should be complete and ready for commuters in 2014. You can watch live construction footage at http://baybridgeinfo.org/construction-cams

 

the tall structure is the new tower for the suspension. photo courtesy of The Twisted Genius

bay bridge construction. click to enlarge

Maybe you don’t consider yourself to be a (helluva) engineer, so I’ll spare you the boring details. But I do want to share one bit that I found interesting. When the bridge is finished, it will be the longest self-anchored suspension (SAS) span in the world (2047 feet). Three months ago, the workers raised the saddle that will hold the cables in place, and it got a lot of attention! The cable saddle weighs approximately 450 tons, and a special crane had to be built just to hoist it up to the top of the tower. It is the biggest saddle of any suspension bridge in the world today! If you want to know more, check out baybridgeinfo.org and sfgate.com/baybridge

the cable saddle. photo courtesy of sirgious

 

the width of the carbon steel cable. photo courtesy of wikipedia.com

bay bridge at twilight

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