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Comment by carsongross | Hacker News Reader

As a reminder, The Golden Gate Bridge, built in 1933, cost $1.5 billion in todays dollars, is 8,980 feet long (to the 11,616 feet of the eastern span) is 746 feet tall (to the 525 feet of the eastern span) and is tremendously architecturally significant, rather than looking like a highway onramp with a small sail plopped on one end of it.

Please stop this ride.

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Not only that, the project had an unprecedented safety record, with many safety measures put in place that went far beyond legal workplace requirements at the time. Also it was completed $1.3 million under budget.

Would you want to be standing on it when an earthquake hits?

BTW the golden gate was built mostly with private funds from bonds ($35M in 1930's dollars)

Also a record of "only" 11 people killed building it.

I would be more comfortable standing on the Golden Gate Bridge than the new Bay Bridge during an earthquake.

That seems foolhardy;

    Immediately following the Loma Prieta quake, the
    GGBHTD engaged a team of consultants to conduct a
    vulnerability study. The conclusion of the study was that
    under a Richter magnitude 7.0 or greater earthquake
    with an epicenter near the Bridge, it would experience
    severe damage that could close this important
    transportation link for an extended period. If a Richter
    magnitude 8.0 or greater earthquake centered near the
    Bridge, there would be a substantial risk of impending
    collapse of the San Francisco and Marin Approach
    Viaducts and the Fort Point Arch, and extensive damage
    to the remaining Bridge structures, including the Main
    Suspension Bridge.

They've spent or authorized nearly $1 billion in additional funds to seismically retrofit the Golden Gate, and the work isn't finished yet.

http://goldengatebridge.org/projects/retrofit.php

That means little without comparison to other bridges. Standing in an open wheat field is probably safer than a bridge, but how does the GGB compare to other bridges?

Also, a Richter 8.0 is a pretty damn hefty quake.

So the GGB would be substantially damaged in an 8.0 quake, but the Bay Bridge is designed to survive and be immediately accessible to emergency vehicles in an 8.5 quake.

Those seem like relatively minor differences, but (assuming the new span actually performs like designed) the Bay Bridge should easily survive an earthquake that is 3.1x larger and releases over 5x more energy than one that will "extensively damage" the Golden Gate Bridge.

http://i.imgur.com/07u65bj.png

I'm familiar with the logarithmic nature of the Richter scale. I was not sure whether the Bay Bridge was indeed designed to survive a larger quake.

Seems an important distinction given that the largest quake recorded in California was a 7.9 and the largest in San Francisco a 7.8.

So presumably an 8.0 is plausible but an 8.5 may not be.

Apparently the maximum 'plausible' (which is a generous modifier) earthquake on the San Andreas is about an 8.3, but the entire fault line from Mexico to Northern California would have to rupture simultaneously. You're right that we're unlikely to see an 8.5.

http://www.smithsonianmag.com/science-nature/what-will-reall...

Construction in 1933 didn't have to care about the environment or the workers, and those add tremendous expense.

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