|The frenchies have one-upped us again
||[Dec. 14th, 2004|11:02 am]
Update: Nevermind! see the strikeout & footnote|
So, this bridge opened yesterday. It's the worlds highest
suspension cable-stayed bridge, is 1.6 miles long, and cost half a billion dollars.
Compare to the new bay bridge, which was supposed to cost 1.8 billion in 1998 dollars. Granted, the bay bridge is a half mile longer, twice as wide, and built over an ocean in the worlds most earthquake prone area, but still; apparently it will cost 4.6 billion for your typical concrete skyway bridge to be built here. Double that if you want a third of it to be a suspension span.
It seems amazing that a seven tower suspension bridge over 1000 feet tall can be built 9 times over for the cost of the new bay bridge. Something doesn't add up.
 I looked at the picture. That is not a suspension bridge. It's a cable-stayed bridge. Compared to suspension bridges, cable-stayeds require less cable, can be constructed out of identical pre-cast concrete sections, and are faster to build, hence the extreme cheapness of it. Makes me wonder what other facts the article fucked up. Which brings us to 
 Why the fuck wasn't the bay bridge cable-stayed? It'd be pretty, cheaper than the current dabacle, and hopefully almost as earthquake-resistant as a suspension bridge. bah. 
 Okay, so I got curious, and cable stayed don't like earthquakes at all. "If any cable is too long or too short, its tension will differ enormously from the the rest of the cables. Therefore, provision is made in a great many cable-stayed bridges for the tension in each wire to be adjustable during the building of the bridge. It is entirely possible to build a suspension bridge with no adjustments at all. Once a bridge has been built, adjustments should not be needed. In practice there may be creep of ground or concrete. More seriously, earth tremors may create significant changes in vital dimensions."