The sinking of the old I90 Bridge was pretty spectacular as well.
https://en.wikipedia.org/wiki/Lacey_V._Murrow_Memorial_Bridg...https://www.youtube.com/watch?v=gm0YQ3vuyyY
I think there was even a song written about it.
All because some dummy left a hatch open and it filled with water. Even more fascinating, I recall that when divers went down to investigate they found a bunch of old cars at the bottom and solved a bunch of missing persons cases.
People apparently drove off of it back when there was a turn around in the middle of it, which was later fixed before the sinking, because so many people drove off the bridge.
Really happy I moved out of the Seattle area. From what I understand most of Seattle-proper is built on sandstone and the fault line running through Seattle seems like a huge liability.
Difference between earthquake insurance in Seattle and just over 100mi south is incredible(~1.5k/mo if I remember correctly).
As a relatively recent Seattle transplant coming from California, WSDoT seems to be one of the worst transportation departments I've seen. The road quality, traffic and general propensity for disaster (in the form of Bertha, bridge collapses, deathtrap viaducts, and destroyed roadways along the mountains lately) seems much higher than I remember in California. Might just be the weather, but I'd love an explanation for why its been so bad.
That is completely true, I have lived here my whole life and it has always been that way. It is weird, we can build airplanes, software and tons of other great things, but the whole transportation thing is just completely baffling to Seattle for some reason.
A friend of mine who's a civil engineer says its because the freeway exits are a mile apart rather than 1.5 miles, so that creates a lot of very short merges and ramps up traffic heavily. What really gets me is the travesty that is 405 between renton and bellevue, feels like it should be 5 lanes but its only 2 full-access lanes and there's a crash every 4 hours because of how much the road bends suddenly.
Wow, what a sprawling article. At first it seems to just focus on how the popular physics class explanation of why the bridge collapsed was wrong...which is mildly interesting but I was hoping from the title that we'd get an indepth look at the engineering processes behind the bridge -- as I remember hearing far more about the bridge in my engineering classes than in physics. But the OP delivers some about the engineering, though I'm largely ignorant of the details about the Tacoma Narrows Bridge (based on the film footage, I had assumed it had happened in the 60s, because I didn't think color footage would have been easy to take in the early 40s).
I liked this detail a third-way through:
> To be fair to Moisseiff and his engineers, the phenomenon of aerodynamic instability wasn't well understood at the time. But it wasn't completely unknown either. The last collapse of a suspension bridge due to its reaction to the wind occurred five decades earlier, when the Niagara-Clifton Bridge fell in 1889. (The heavyset design of the Brooklyn Bridge, which opened five years earlier, in 1883, was meant to withstand the sorts of forces that had affected suspension bridges in previous decades.)
> Just four months after Galloping Gertie collapsed, a professor of civil engineering at Columbia University, J. K. Finch, summarized suspension bridge failures in an article in Engineering News Record. "These long-forgotten difficulties with early suspension bridges, clearly show that while to modern engineers, the gyrations of the Tacoma bridge constituted something entirely new and strange, they were not new—they had simply been forgotten."
The most recent example of a similar failure was 50 years earlier. No doubt the information would propagate to some degree through engineering libraries...but given how much we today forget about engineering failures and case studies (in the software engineering context, some would argue that the memory hole cycle seems to be about 6 months long) despite vastly improved information pipelines, I've always wondered how difficult it was to learn and maintain best practices in the engineering disciplines before the past few decades.
Yes. I HATE reporting like this. I've got things to do with my life. I'd much rather they just get on with the information. If they feel there's some human interest necessary to understand the point, at least give me a summary up front, so I can decide if it's going to be interesting and worth the investment of time.
There was a time when this was the way to write, to give depth to your readers. The New Yorker is a classic example of this writing style. It's for people who want to read, and have time to do it. Maybe 150 years ago, people had more time than they had material to read, so this style was perfect.
But now there's so much more to read then there is time to read it in, and this style is a royal pain. Times have changed, and (some) writers haven't noticed. They're still writing like we have more time than we have stuff to read.
In all seriousness, this type of writing - sprawling as you call it - is important. It lets the reader come away with a sense of the nuances of the situation, instead of a bullet point abstract that leads to misunderstandings and overlooked issues. This type of writing - commonly called "the essay" - is important precisely because it does take time to read it. Its meant to teach you something, not just give you a little factoid you can regurgitate throughout the day.
Yes, you're very important and don't have time to read long articles. If you don't want to read long-form writing, then don't do so but don't complain about it being available to people who like it. I rather like the New Yorker.
It's not that "I'm very important". It's not even that I don't have time to read a long article. I don't have time to read nearly as many long articles as there are out there, though.
And to me, it feels like the shoe's on the other foot. To me, a long form article is the author deciding that he/she's so important (or the content is) that I will find it worth the time to read the whole thing, and that it's therefore fine to hide the main point somewhere in the length, because I'll get the point so much better if I go through all the rest of it as well. That's fine for those who like that kind of thing, but, well, let's just say that it's unattractive to more and more readers as we have more and more things that we want to read.
For it to be worth my while, this article has to be worth more than whatever I didn't have time to read because I took the time to read this one. The longer the article is, the higher that bar is, because the more I could have read with the same time.
I was unnecessarily snarky. However, this is a market-correcting thing. Yes, there is a trend toward shorter pieces, which has pluses and minuses. If I write long pieces that people don't read, I may shorten what I write. Or I may not, if I feel the greater length is justified. And if some choose not to read the longer piece, I'll probably be fine with that.
Agreed. I quite liked the level of detail in this article, but probably because I'm already interested in the Tacoma Narrows Bridge.
In general this rambling style is a complete turn-off for people who (1) aren't already familiar with the topic and (2) don't have 40 hours a week to spend reading. It boggles the mind how many supposedly tech-focused articles are pumped full of human interest fluff. For example, any article that starts with someone's physical description ("John Smith was hunched in front of his computer, his messy brown hair almost completely obscuring the screen.") is almost guaranteed to be of this ilk.
To be fair, I have a lot of time on my hands :). In defense of the OP, they are covering one of the oldest and most well-known engineering history lessons, not a new trend or news event. A lot of history we take as gospel gets summed up in glib paragraphs, so if someone is purporting to explain why something has been wrong for decades, I won't hold it against them if they take more than the usual amount of words to get there.
But they aren't filling the article with useful facts or details. It's all intellectual popcorn. Mention that something big is coming up, then mention what the main engineer ate for breakfast, then pause to lament the fact that people often skip breakfast, and finally reach your big reveal.
Then claim the fact that it rambles is proof of good writing.
Exactly. This particular article isn't providing much depth. It's mostly misdirection followed by a dramatic revelation of the generally-accepted answer. The dominant guess at the failure mode of that bridge has been flutter for a very long time.
Anyone else who has gone through the mechanics and disagrees with me on this, please let me know your thinking.
Despite the length of the article, the author has missed an important point - the Golden Gate Bridge had the same problem. After the Tacoma Narrows Bridge, the Golden Gate Bridge had the greatest length to width ratio of any suspension bridge.
This was a major concern at the time, but wasn't publicized. It was dealt with in 1951, by attaching huge stiffening trusses under the deck.[1][2] If you've seen the underside of the Golden Gate Bridge, you've seen the trusses, which are not original. Prior to that stiffening, the bridge would twist in high winds, on one occasion enough that light poles hit the suspension cables.
I don't have a comprehensive resource, but the other one that comes to mind is covered in an episode of the "99% Invisible" podcast titled "Episode 110: Structural Integrity".
My grandfather -- who lived in the Bay Area when the Golden Gate Bridge opened -- would recount the early days of the bridge when, on a windy day, the span would bounce and twist so much that you could (in his words) "lose sight of the car in front of you." I can only imagine how harrowing that windstorm must have been on December 1, 1951 that "threatened the integrity of the Bridge"...
Meh. Seems like a faux controversy. I looked into this a year ago when showing off some simulation software, and read that as best anyone can tell, it was probably flutter.*
In my reading I didn't run into anybody saying that the wind was fluctuating at the natural frequency of the bridge! I also read that the "vortex street" model for the failure had been proposed but discarded during the initial investigation.
After my brief look into it, I got the idea that no serious workers have believed those wrong ideas for many decades.
If some high school teachers somewhere say this was "resonance," that is correct and probably worth teaching ... it's just not resonance at the natural frequency of the bridge in still air.
*Flutter is pretty cool physics. Pinch one end of a a business card, then point the free end of the card into a fan. When the airspeed gets high enough, the card should oscillate like a clarinet reed. Torque from the airstream opposes the restoring torque that keeps the bridge (or business card) level. As the airspeed grows, the net restoring force drops towards zero and the resonant frequency falls. At zero you're toast, there's no net restoring force at all.
27 comments
[ 2.8 ms ] story [ 57.7 ms ] threadAs are most Seattle natives, I'm waiting for 'the big one' to bring down our other terrible bridge-ish thing, The Viaduct.
But this is probably all for nothing once they find Cthulu as the Bertha drill starts moving again, only three years behind schedule on that one!
The Bulge was well-known to eat cars: http://blog.seattlepi.com/bellevue-pi/2011/05/18/looking-bac...
Difference between earthquake insurance in Seattle and just over 100mi south is incredible(~1.5k/mo if I remember correctly).
I liked this detail a third-way through:
> To be fair to Moisseiff and his engineers, the phenomenon of aerodynamic instability wasn't well understood at the time. But it wasn't completely unknown either. The last collapse of a suspension bridge due to its reaction to the wind occurred five decades earlier, when the Niagara-Clifton Bridge fell in 1889. (The heavyset design of the Brooklyn Bridge, which opened five years earlier, in 1883, was meant to withstand the sorts of forces that had affected suspension bridges in previous decades.)
> Just four months after Galloping Gertie collapsed, a professor of civil engineering at Columbia University, J. K. Finch, summarized suspension bridge failures in an article in Engineering News Record. "These long-forgotten difficulties with early suspension bridges, clearly show that while to modern engineers, the gyrations of the Tacoma bridge constituted something entirely new and strange, they were not new—they had simply been forgotten."
The most recent example of a similar failure was 50 years earlier. No doubt the information would propagate to some degree through engineering libraries...but given how much we today forget about engineering failures and case studies (in the software engineering context, some would argue that the memory hole cycle seems to be about 6 months long) despite vastly improved information pipelines, I've always wondered how difficult it was to learn and maintain best practices in the engineering disciplines before the past few decades.
Yes. I HATE reporting like this. I've got things to do with my life. I'd much rather they just get on with the information. If they feel there's some human interest necessary to understand the point, at least give me a summary up front, so I can decide if it's going to be interesting and worth the investment of time.
But now there's so much more to read then there is time to read it in, and this style is a royal pain. Times have changed, and (some) writers haven't noticed. They're still writing like we have more time than we have stuff to read.
In all seriousness, this type of writing - sprawling as you call it - is important. It lets the reader come away with a sense of the nuances of the situation, instead of a bullet point abstract that leads to misunderstandings and overlooked issues. This type of writing - commonly called "the essay" - is important precisely because it does take time to read it. Its meant to teach you something, not just give you a little factoid you can regurgitate throughout the day.
And to me, it feels like the shoe's on the other foot. To me, a long form article is the author deciding that he/she's so important (or the content is) that I will find it worth the time to read the whole thing, and that it's therefore fine to hide the main point somewhere in the length, because I'll get the point so much better if I go through all the rest of it as well. That's fine for those who like that kind of thing, but, well, let's just say that it's unattractive to more and more readers as we have more and more things that we want to read.
For it to be worth my while, this article has to be worth more than whatever I didn't have time to read because I took the time to read this one. The longer the article is, the higher that bar is, because the more I could have read with the same time.
In general this rambling style is a complete turn-off for people who (1) aren't already familiar with the topic and (2) don't have 40 hours a week to spend reading. It boggles the mind how many supposedly tech-focused articles are pumped full of human interest fluff. For example, any article that starts with someone's physical description ("John Smith was hunched in front of his computer, his messy brown hair almost completely obscuring the screen.") is almost guaranteed to be of this ilk.
Then claim the fact that it rambles is proof of good writing.
Anyone else who has gone through the mechanics and disagrees with me on this, please let me know your thinking.
This was a major concern at the time, but wasn't publicized. It was dealt with in 1951, by attaching huge stiffening trusses under the deck.[1][2] If you've seen the underside of the Golden Gate Bridge, you've seen the trusses, which are not original. Prior to that stiffening, the bridge would twist in high winds, on one occasion enough that light poles hit the suspension cables.
[1] https://books.google.com/books?id=ug9YEcgBYs8C&pg=PA31&lpg=P... [2] http://goldengatebridge.org/research/majggbimprove.php
Side question: Is there a good place to learn about major structural engineering fixes that were kept secret until the work was completed?
http://99percentinvisible.org/episode/structural-integrity/
http://www.slate.com/blogs/the_eye/2014/04/17/the_citicorp_t...
An updated link to the New Yorker piece mentioned in the article is http://people.duke.edu/~hpgavin/cee421/citicorp1.htm
Or if you have a New Yorker subscription http://www.newyorker.com/magazine/1995/05/29/the-fifty-nine-...
I'd actually read the New Yorker article first, then read the more recent reporting.
edit: this is the same story mentioned by jonlucc in sibling comment.
In my reading I didn't run into anybody saying that the wind was fluctuating at the natural frequency of the bridge! I also read that the "vortex street" model for the failure had been proposed but discarded during the initial investigation.
After my brief look into it, I got the idea that no serious workers have believed those wrong ideas for many decades.
If some high school teachers somewhere say this was "resonance," that is correct and probably worth teaching ... it's just not resonance at the natural frequency of the bridge in still air.
*Flutter is pretty cool physics. Pinch one end of a a business card, then point the free end of the card into a fan. When the airspeed gets high enough, the card should oscillate like a clarinet reed. Torque from the airstream opposes the restoring torque that keeps the bridge (or business card) level. As the airspeed grows, the net restoring force drops towards zero and the resonant frequency falls. At zero you're toast, there's no net restoring force at all.