Pineapple Express: Someone Is Wrong on the Internet?

[Scribe]

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You all are hurting yourselves over thinking it. It's always more simple than you believe.

 

[Ryujin]

Ah, the Tacoma Narrows Bridge...the textbook bridge example for aerostatic* flutter. (Seriously: it's in every structural engineering textbook published since 1940.)

*woops, it was aeroelastic flutter. Sorry; I'm a water engineer--not a bridge engineer.

I was watching a show about architectural failures and, after a couple of seasons, was flabbergasted at the number of replacement bridges I'd been on when visiting Washington State. Makes me want to take the ferries more.

 

[Deset Gled]

I was watching a show about architectural failures and, after a couple of seasons, was flabbergasted at the number of replacement bridges I'd been on when visiting Washington State. Makes me want to take the ferries more.

I like to look at it the other way. If you're on a bridge (or building, etc) that fell down once, you're probably about as safe as possible. They've seen what went wrong, and fixed it the next time. If you're on something old enough to pre-date modern standards that's never had a major disaster, you're living on Survivorship Bias and hoping for the best.

 

[Ryujin]

I like to look at it the other way. If you're on a bridge (or building, etc) that fell down once, you're probably about as safe as possible. They've seen what went wrong, and fixed it the next time. If you're on something old enough to pre-date modern standards that's never had a major disaster, you're living on Survivorship Bias and hoping for the best.

And I see it as, "A metric crap-tonne of bridges around here have failed and I'm now on one of them that hasn't. Yet."

 

[Umbran]

If you're on something old enough to pre-date modern standards that's never had a major disaster, you're living on Survivorship Bias and hoping for the best.

You call it survivorship bias, but if you are on something old enough to pre-date modern standard, you are on something that has already survived the regular things the area throws at it for, like, half a century or more. It will only fall over due to unpredictable circumstances that it wouldn't have been designed for anyway, or due to lack of maintenance.

Remember - the Tacoma Narrows bridge didn't collapse under odd circumstances. Those were the normal wind conditions in the area. The bridge's movement was noted during construction, and the thing lasted about four months before collapsing.

 

[Thomas Shey]

Ah, the Tacoma Narrows Bridge...the textbook bridge example for aerostatic* flutter. (Seriously: it's in every structural engineering textbook published since 1940.)

*woops, it was aeroelastic flutter. Sorry; I'm a water engineer--not a bridge engineer.

Its--dramatic. People know about it that don't know about any of the other--quirks--of civil engineering.

 

[Thomas Shey]

You call it survivorship bias, but if you are on something old enough to pre-date modern standard, you are on something that has already survived the regular things the area throws at it for, like, half a century or more. It will only fall over due to unpredictable circumstances that it wouldn't have been designed for anyway, or due to lack of maintenance.

Remember - the Tacoma Narrows bridge didn't collapse under odd circumstances. Those were the normal wind conditions in the area. The bridge's movement was noted during construction, and the thing lasted about four months before collapsing.

On the other hand, you'd better hope it hasn't just been taking incremental damage the whole time and you're waiting around for that one-more-thing. Los Angeles has been learning that with its water main and drainage systems the last few years.

 

[Umbran]

On the other hand, you'd better hope it hasn't just been taking incremental damage the whole time and you're waiting around for that one-more-thing.

What on this good green Earth do you think "lack of maintenance" means?

 

[Thomas Shey]

What on this good green Earth do you think "lack of maintenance" means?

All right, that's fair. But its also a pretty big qualification, given some infrastructure issues in the U.S. these days. The best you can hope for is that the most critical things end up at the front of the backlog (which is why its so shocking when bridges don't end up there).

 

[Umbran]

All right, that's fair. But its also a pretty big qualification, given some infrastructure issues in the U.S. these days.

Yes and no. I mean, there are issues, but how many bridges actually fail each day? What is the likelihood you are on the (less than) one that does so?