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Bridge over troubled waters: the new SF Oakland Bay Bridge

  Self-anchored suspension section of SF-Oakland Bay Bridge

Ever since the Romans started building them, bridges have been one of the most difficult of public works projects to complete. New York’s Brooklyn Bridge and San Francisco’s Golden Gate Bridge were beset by those who said they couldn’t be constructed or, if they were, they wouldn’t stand for long. In the case of both of those iconic structures, the engineering and technological challenges were the rationale for those who said they couldn’t be done.

 

These days, it’s not engineering or technology that mucks up big projects, it’s politics and bureaucracy. New York’s World Trade Center has been locked up in political and business wrangling over how and what and why to rebuild. Here in San Francisco, now that the new east span of the Bay Bridge is visible and the suspension portion is taking form, it’s easy to forget this too was a bridge with a troubled past.

 

Like many important Bay Area structures, the bridge was damaged in the 1989 Loma Prieta earthquake. Subsequent analysis indicated that the eastern span (from Yerba Buena Island to Oakland) could not feasibly be retrofitted. A new span was the only choice if a repeat of the 1989 bridge failure was to be avoided in the coming “big one”. The controversy began almost immediately.

 

In all fairness, the first debate on the bridge was engineering in nature. The question was this:  should the final portion of the bridge, the connection to Yerba Buena, be a suspension bridge or a stayed cable bridge? While the distinction between suspension and stayed cable is not familiar to the average non-engineer, when you’re building something as expensive as a bridge, it’s important to get it right. T.Y. Lin, the lead bridge engineers, took a novel approach; they set up a design competition between two teams with each team taking one of the design approaches, suspension or stayed cable. Ultimately, a variant called a “self-anchored suspension” (SAS) bridge was selected.

 

And then, the politicians started adding their two bits. Willie Brown, then mayor of San Francisco, became a bridge engineer overnight. He “discovered” that the bridge design was “unsafe” and recommended that the bridge alignment be moved 178 feet to the south of the proposed alignment. How that would make for a safer bridge was not clear; one thing it did do was make land available on Yerba Buena Island, where coincidentally, Mayor Brown was promoting a new high end development scheme. Even the then mayor of Oakland, Jerry Brown, entered into this silliness. Eventually, the soon-to-be-recalled Governor of California, Gray Davis, had to step into the mess and decide that the bridge would be just fine where it was planned. But the entire episode delayed the bridge further.

 

Not to be outdone by the Democrats, Republican Governor Arnold Schwarzenegger, a few years later, acquired vast knowledge on the economics of bridge building. This time it was not the alignment of the bridge, but the cost of the self-anchored suspension section. Far better, in Schwarzenegger’s opinion, to make the entire eastern span one long “freeway on stilts”. The problems were manifold, however, with a change like this. Changing a bridge design, especially when part of it was already under construction, is, in the best of scenarios, a mess. Modern bridges have millions of components; it’s not technically possible to change some of them without affecting most of the rest of the bridge. The Governor’s suggested change, after making all the other necessary design changes, would likely have cost more than leaving the current design in place. Finally, the Governor backed down when the reality became clear. But this episode, too, delayed the bridge further.

 

The cost of the eastern span went out of control as well. Originally, estimated by the state at $2.6 billion, the bridge will be completed at a cost of $6.3 billion and maybe more. Now, in the scheme of large public works projects, this is not so unusual. Boston’s Big Dig went from $2.8 billion to over $15 billion and that doesn’t include the debt service of $7 billion that the public ended up carrying.

 

A big part of the uncertainty in estimating the cost of large projects is the uncertainty attached to construction bids that happen far in the future. To put it in an everyday context, could you predict the cost of a gallon of gas five years from now with any precision, really? What if you had to set aside all the money now for the gasoline that you planned to buy in five years? You get the idea.

 

That being said, the California Department of Transportation (CalTrans) did fail to factor in one important development; the explosive growth and rapid pace of construction in China. What on earth would office buildings in China have to do with a bridge in California? It’s fairly simple. At any given time, there is a global capacity for making concrete and steel, two absolutely necessary components in bridges. When that capacity is stretched, as the rapid growth of China caused, what happens? You guessed it, the price of concrete and steel go up worldwide. As it turned out, the price went way up. While those prices can’t be precisely predicted, the trend can be predicted and, yes, CalTrans has access to that information. I will leave it to your wisdom to decide whether CalTrans badly erred on their construction estimates or whether, once again, politics came into play and the number given to the public was kept as low as possible.

 

This brings us to the present day. The “skyway” sections of the bridge are nearly complete. The SAS section, the cool part, of the bridge is just beginning. Over the next couple of years, we will see the elegant and graceful suspension form arise. I don’t think it is any accident that the design team employed the architect Donald MacDonald (who incidentally, just published a charming volume on the Golden Gate Bridge) as the architect for the bridge. As MacDonald told me, “Bridges are icons, symbols of civic pride and people of Oakland, in particular, want that.” I would posit that our bridges need to be not only structurally safe, economically feasible, but they must be beautiful. 

 

In spite of all the politics and cost snafus, I think by 2013 that’s just what the San Francisco Oakland Bay Bridge will be—an iconic structure identifying Oakland and the Bay Area.

For more info: Bay Bridge 360 (this website has construction videos and computer animations of the bridge)