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FIU had grand plans for 'signature' bridge. But the design had a key mistake

143 points by danso 8y ago

danso 8y ago
Saw this story via an @EdwardTufte tweet: https://twitter.com/EdwardTufte/status/1007395311541682176 https://twitter.com/EdwardTufte/status/1007395311541682176 > A+ This is beautifully executed technical report by the Miami Herald, an instant classic of news reporting. Note that this report is a document not a deck. The FIU admistration loaded the bridge design down with features.
- ScottBurson 8y ago
  Wow, I thought it seriously needed an editor to take an axe to it. I usually like long pieces, but this just seemed repetitive.
  - jacobolus 8y ago
    The way newspaper articles work, not every reader is expected to read the whole thing. They are structured to put critical information up front, so that a reader can stop whenever they lose interest without missing anything more important than what they already read, but include additional detail below for those who are more deeply interested. This leads to the same main points being repeated several times, which can be a jarring style for readers who are not used to reading newspapers. Long magazine articles are typically structured quite differently.
    - oftenwrong 8y ago
      It's known as the "inverted pyramid" style: https://en.wikipedia.org/wiki/Inverted_pyramid_(journalism) https://en.wikipedia.org/wiki/Inverted_pyramid_(journalism)
    - ScottBurson 8y ago
      Except it didn't seem like there was much more detail as I kept reading. That was my impression, anyway — I'm not inclined to reread it to see if I overlooked something.
- keithpeter 8y ago
  “This is not a big project," Beck said. "It’s a darn pedestrian bridge.” Quote from one of the expert engineers from OA. It is the last sentence in the article, and I think a very effective final comment. However, the article does quote two of the expert engineers as saying that the faux suspension bridge design could have been perfectly stable, had the trusses been strong enough. I was interested in the comment that had the two end pieces been in place, then the bridge may well have been fine - the plan was to swing the main bridge section into position then build the two end pieces in situ. One wonders about the design calculations for each stage of the proposed construction. I think there is a book length work around the details of the decision making process once the investigation is complete and the legal fall-out has been dealt with.
- ghostly_s 8y ago
  This seems a rather trite and self-serving take. 'Loaded down with features'? It seems the conclusion is there was exactly one problem, change the angle of structural members for aesthetic reasons without adequate structural analysis.
abraae 8y ago
> But FIU's bridge was designed to mimic the dramatic look of a cable-stayed bridge, where the deck is suspended from cables fanning out from a tall mast. In FIGG's design, though, the "cables" — actually metal pipes — were mostly just for show. The diagonal, v-shaped struts of the truss did the structural work. I've always found it useful to hone in on anything that is done purely for aesthetic reasons. We build a house recently. I really wanted exposed rafters, there was some complexity around insulation, and the architect responded by proposing some "faux" rafters. The idea was so revolting that it prompted more examination, which identified some mistakes. In the end, a simpler, better, cheaper solution was found that did not have faux elements in it.
- deleted 8y ago
  [deleted]
- crwalker 8y ago
  Yes! Good thing you pushed back on the architect. I have a similar design philosophy that honesty is more aesthetically pleasing than deception. When designers resort to faux materials and structures, the truth still tends to peek through, resulting in an 'uncanny valley' of forms. For example: * Brickwork veneers bend in the wrong spots * Faux beams are placed in the wrong locations with the wrong joints, announcing that they can't bear a load There's certainly a place for decorative elements, just not decorative elements pretending to be something else. I spent several summers framing houses, so I'm looking forward to an opportunity to design my own house - and maybe 3D printing it.
  - function_seven 8y ago
    The worst example of this are those faux shutters that seem to outnumber real ones. They're rarely wide enough to actually cover the adjacent window! https://imgur.com/a/o9Nxx6c https://imgur.com/a/o9Nxx6c EDIT: Added examples of fake garage door handles and hinges. I'm seeing that a lot more and don't understand the point.
    - seszett 8y ago
bthrm 8y ago
Isn’t this the famous “feminist” bridge?
- recursive 8y ago
  I've never heard of a feminist bridge, so if it is, it's not that famous.
cagenut 8y ago
This is a really good article. Amazing how a dozen+ different things combined to produce the unfortunate result. Perfect case study in there being no such thing as a singular 'root cause'.
- Shank 8y ago
  I concur on the quality of the article, but I would say it goes further: The Miami Herald is even suing to get public records requests filled in the interest of journalism. They’re doing an exceedingly good job at trying to get answers to tough questions.
  - JauntyHatAngle 8y ago
    I am ignorant as to this whole story, but out of interest, why is it a bad thing to wait for the NTSB report? Often it is good to wait for an entire report to nail down the facts before the witch hunt should begin, is there something in this case that means this isn't the best idea?
    - danso 8y ago
      I imagine the Herald doesn't believe that the NTSB (or any authority) necessarily has the canonical and final word on things, and thus the Herald sees itself as providing an independent viewpoint/assessment. One of the undercurrent themes of this story is that, according to the herald, the construction company and FIU officials are well-connected politically. Possibly related to this is the fact that the Herald is suing the state for records related to the bridge [0]. These records were determined to be public but have so far been withheld from public release. [0] http://www.miamiherald.com/news/state/article212489364.html http://www.miamiherald.com/news/state/article212489364.html
      - JauntyHatAngle 8y ago
        So the prevailing thought is that the NTSB is delaying the documents to protect FIU officials, and not to prevent undue influence of the public before the release of the report? It certainly doesn't look good from this quoted paragraph... "Public records made and received by the Department from February 20 until the bridge collapsed on March 15 obviously were not obtained by the Department during an investigation because there had been no accident, much less an investigation into an accident,'' he wrote in a response to the FDOT motion to dismiss the lawsuit. "Florida law is clear that if an agency’s record is a public record at the time it is made or received, then that document does not lose its character as a public record if the document is later given to an investigative agency in the course of a subsequently initiated investigation." Still could be to prevent a public outcry before the facts are in, but that does seem mighty fishy...
ams6110 8y ago
There are some parallels with software. Encryption for example. Don't deviate from standard implementations unless you really know what you're doing. And even then, review it and review it again. Preferably by a separate expert.
- otakucode 8y ago
  The parallels do not go very far, unfortunately. When software fails, and kills people, it is rarely investigated. It's development is rarely investigated. When that is done, however, the differences widen even further. There is no degree to which software development can be done incompetently that criminal negligence charges can succeed. We saw this proven within the past decade when some of Toyotas cars engaged in "unintended acceleration." Despite the developers being denied even tools as basic as a bug tracker, and despite following only 4 out of over 90 'required' or 'suggested' coding practices advised by the automotive industry, the courts ruled that because no actual standards exist for software development, the management of the company could not be held criminally liable for the deaths they caused. This problem will re-appear. When a bridge collapses, if they found out the company building it hired the cheapest engineers right out of school, denied them access to tools or training needed to do their job, kept them removed from decisions about scheduling, ignored any concerns voiced about needing more time for proper development and testing, multiple people (the ones who wear suits) would go to prison and the company would likely be destroyed. If a few executives were put in prison over shoddily made software rushed to market, I imagine we would see changes in how software is developed of monumental proportions. But not until then, apparently. And that day doesn't seem to be coming soon. Perhaps self-driving cars will herald such a wake-up call. I know I'm certainly not trusting one until things change drastically.
  - JohnJamesRambo 8y ago
    I like your viewpoint. I’d be more inclined to call programmers engineers under your proposed system.
    - otakucode 8y ago
lrn 8y ago
The Fountainhead Chapter I; Howard Roark to the Dean --- "Why do you want me to think that this is great architecture?" He pointed to the picture of the Parthenon. "That," said the Dean, "is the Parthenon!" "So it is." "I haven't the time to waste on silly questions." "All right, then." Roark got up, he took a long ruler from the desk, he walked to the picture. "Shall I tell you what's rotten about it?" "It’s the Parthenon!" said the Dean. "Yes, God damn it, the Parthenon." The ruler struck the glass over the picture. "Look, " said Roark. "The famous flutings on the the famous columns—what are they there for? To hide the joints in the wood—when columns were made of wood, only these aren't, they're marble. The triglyphs, what are they? Wood. Wooden beams, the way they had to be laid when people began to build wooden shacks. Your Greeks took marble and they made copies of their wooden structures out of it, because others had done it that way. Then your masters of the Renaissance came along and made copies in plaster of copies in marble of copies in wood. Now here we are, making copies in steel and concrete of copies in plaster of copies in marble of copies in wood. Why?"
- RcouF1uZ4gsC 8y ago
  Then again the Parthenon has has been around for nearly 2,500 years (finished in 432 BC), and during that time has been considered by people from all over the world one of the most beautiful buildings ever built. What building by modern architects will even be around 500 years from now, much less revered as an example of beautiful architecture?
  - carapace 8y ago
    Saint Mary's Cathedral (in San Francisco) I don't say it's as beautiful as the Parthenon, and it might not last 500 years, but we moderns aren't completely shabby... https://en.wikipedia.org/wiki/Cathedral_of_Saint_Mary_of_the_Assumption_(San_Francisco,_California) https://en.wikipedia.org/wiki/Cathedral_of_Saint_Mary_of_the... > Its saddle roof is composed of eight segments of hyperbolic paraboloids, in such a fashion that the bottom horizontal cross section of the roof is a square and the top cross section is a cross. The interior is open.
    - 8y ago
VirtualAirwaves 8y ago
They spent way too much of other people's money to build something that wasn't sound. There's blame all around here.
RcouF1uZ4gsC 8y ago
> At least one said that if so, it constitutes an avoidable mistake on a bridge that should never have been so complicated. >“This is not a big project," Beck said. "It’s a darn pedestrian bridge.” There is something to be said about not over-complicating designs, whether it be in actual construction or in software.
- bsder 8y ago
  Many people said the same thing about the Eiffel Tower ...
  - paulie_a 8y ago
    Which was built for the world's fair and was supposed to be torn down after.
- stevenwoo 8y ago
  They had many similar goals for a pedestrian bridge in California around 2008 or so, but they chose steel instead of concrete, a properly engineered concrete one got much more expensive bids. It's always kind of weirdly delightful to go home from a trip out of town and pass under it on I-280. https://en.wikipedia.org/wiki/Don_Burnett_Bicycle-Pedestrian_Bridge https://en.wikipedia.org/wiki/Don_Burnett_Bicycle-Pedestrian...
ebikelaw 8y ago
The article barely touches on the subject, but the bridge was really unnecessary, or necessitated only by the nonsensical urban design surrounding the university. The student housing is not only on the opposite side of a gigantic road from the campus, but it's further separated by a canal and then acre after acre of parking. If any attention had been paid, at all, ever, to the built environment this bridge would not have been needed in the first place.
- jessaustin 8y ago
  You have to put the acres of parking next to the buildings! Otherwise the drivers would have to walk!!1!
- pseingatl 8y ago
  The community was there before the university. It wasn't that long ago that it was Tamiami Airport, which has now moved even further west.
- oftenwrong 8y ago
  This area is like the endgame of the American suburban experiment. It is designed to be a collection of nice, isolated, suburban communities connected by a sprawling, auto-centric hellscape of oversized roads.
ndespres 8y ago
> And in order to pull off the aesthetic, the bridge's designers had to make the diagonal supports beneath them a variety of different shapes and sizes. That complication may have led the designers to miss a crucial error, independent engineers who've examined the bridge's plans believe: One of the supports was not strong enough. They aren't joking about the "variety of different shapes and sizes" for the diagonal supports. It's really incredibly ugly. In my view any "aesthetics" gained from the fake cables on the bridge are far outweighed by how goofy the whole thing looks when viewed from the side. It's really jarring, and I imagine that it would look rather cobbled together when walking over it. I also was shocked by the reported "2000 pages of calculations" that 3 different structural engineers signed off on. I have a hard time imagining that none of these experts might have said at some point, "this is a bad bridge that should not be built!" even if mathematically it could have survived magnitude 10 earthquake. Which it clearly couldn't. I'm not an engineer but it ought to be outside the ethics of an engineer's role in approving a bridge design that appears to have redundancy (the cable stays AND the diagonal supports) when the cable stays are merely a foolish aesthetic choice. Doesn't seem much different than selling a car with an airbag icon on the steering wheel when no such airbag exists. It's a false claim to structural integrity. One final thought- the PURPOSE for this bridge seems ill-conceived in the first place. Why is the campus divided by a highway to begin with?? But that's neither here nor there.
- CtrlAltT5wpm 8y ago
  > Why is the campus divided by a highway to begin with?? But that's neither here nor there. That's probably more circumstance than anything else. The area immediately north of the campus has a lot of residential housing, attractive to both students and employees, moreso because Miami's public transit is gawdawful; if you can walk to school/work, avoiding the traffic, that's a bonus. Additionally, the campus wasn't always the behemoth it is now. The highway they speak of is SW 8th Street, or Tamiami Trail, if memory serves. It's a main road in the area The campus was always adjacent, but only semi-recently has it begun to truly crowd the road, likely a byproduct of all the insane construction going on in the school. FIU is far from the only school spending ridiculous money on infrastructure. The school was never really plopped down next to a major highway...they both just grew, and city planning has never been the area's strong point.
ceejayoz 8y ago
> "This structure should function as more than just a path for circulation; it should be a place to be and a place to be experienced, and the FIU campus and its students must be proud of it," the document's introduction reads. "It should be a destination in its own right where community members might linger, gather, and create an urban social space — a linear park." This reads a lot like every startup that tries to convince themselves that their run-of-the-mill CRUD app is "changing the world".
- JohnJamesRambo 8y ago
  “Hey guys let’s go hang out on the bridge over the highway.” It is like a plaza, but a bridge! Ignore the fumes and deafening roar of traffic.
  - PebblesRox 8y ago
    A successful example of this is the I-670 cap bridge in Columbus, OH. The bridge is lined with buildings so it’s hard to tell you’re even on a bridge. It has the advantage of being over a sunken highway, so there’s no grade change to deal with. https://www.google.com/search?q=the+cap+at+union+station&lr=&hl=en&prmd=minv&source=lnms&tbm=isch&sa=X&ved=0ahUKEwie1aul0NTbAhWszlkKHe1LBj4Q_AUIEigC&biw=1024&bih=653#imgrc=DGkhBEXptBzdmM https://www.google.com/search?q=the+cap+at+union+station&lr=...:
    - pseingatl 8y ago
      Or the Rialto.
- deleted 8y ago
  [deleted]
peterwwillis 8y ago
So many concrete bridges fail for so many reasons, it's kind of crazy that we keep building them. It's much easier to inspect and repair steel than concrete, and it fails more gracefully. Also, I'm not even an engineer and I can tell you that uneven strut design would give you uneven loading on the span. Christ. Why didn't they just build a damn cable stayed bridge?! If traffic was a concern, they could have built it half cantilever, half guyed. No formwork, strong, still visually appealing, no stupid truss design, and no concrete.
- WalterBright 8y ago
  The struts varied in thickness according to their net loads, so their loading should have been the same.
- yardie 8y ago
  It was a cable stayed bridge. The bridge span was just put up. The tower and the cables were to be installed over the next few weeks. They allowed traffic under an incomplete bridge because money.
  - deleted 8y ago
    [deleted]
  - hrunt 8y ago
    It specifically was NOT a cable-stayed bridge. It was a non-redundant truss bridge with a tower and faux stays that contributed nothing to the structural capabilities of the bridge. The arrangement of the truss structure mimiced the stay angles purely for aesthetics, not for any other reason. The choice to use a single truss structure rather than a more traditional redundant set of trusses was due to the desire for a striking design. Adding the tower or cables would have done nothing to strengthen the bridge. The engineers in the article suggest that the second shorter section of the bridge to be built afterwards may have alleviated some of the stresses on the north truss beam, but the truss itself was unorthodox, so they cannot say anything for certain.
    - 8y ago
WalterBright 8y ago
"But they suggested that over-reliance on the computer models, a common pitfall in the profession, may have played into it." It's very easy to be seduced into assuming a computer model's results are correct. Computer models of critical bits should always be double-checked by a separate independent calculation. For this bridge, a simple analysis of static forces should have been sufficient for a cross-check, despite the article repeatedly implying this was a difficult/tricky computation. It is not.
- hinkley 8y ago
  If you did find a way to design a structure so that analysis of the static forces was not straightforward, might that be a good indication that you shouldn’t build it at all?
  - antod 8y ago
    Not necessarily. Static analysis means a specific thing in structural engineering. Pin jointed frames with diagonal members (eg trusses) are easy to analyse with just geometry (statically determinate). But moment resisting frames without diagonals are not statically determinate and require more iterative calculations (usually computer modelled these days). Doesn't mean you shouldn't build them though.
    - WalterBright 8y ago
      Doing a pin joint frame static analysis is simple, and will yield a lower bound on the loads on the struts. It would serve as a good cross check on the computer model.
- Mtinie 8y ago
  Static force analysis only works when the materials being modeled are well known. Titanium dioxide concrete is a novel material—and, from the article’s text and subsequent research—appears to have a narrow effective range before integrity issues appear.
  - 8y ago
scarejunba 8y ago
Maybe this will put paid to the nonsense people constantly spout about "real engineering". Turns out doing new things is hard. But also let's be real, you're not going to cross a 10-lane stroad, bridge or no bridge and feel like you're in 'a college town'. It was never gonna happen.
m0llusk 8y ago
Odd that there is no mention of the analysis on AvE YouTube. The support structure used was substantially different from the one planned and it was the post tensioning process that triggered the failure. It is possible that using the planned supports might have allowed the structure to endure the post tensioning procedure.
- timpattinson 8y ago
  AvE might work in engineering, but I don't think he's a structural PE.
  - m0llusk 8y ago
    What has that got to do with anything? He got input from a range of sources including claimed structural engineers and correctly identified the point of failure during postensioning.
nkoren 8y ago
> The FIU bridge was meant to mimic the look of a cable-stayed bridge. But the 'cables' were actually steel pipes that didn't play a structural role I spent 13 years, in various capacities, studying architecture and working as an architect. Bullshit like this reminds me why I don't miss it. Vapid pasted-on "signifiers" that are not merely devoid of sensibility, but aggressively hostile towards it. Engineers fighting to coerce the pastiche into something that won't kill people. If you're not an architect and you're feeling generous -- like, maybe you're just having your daily dose of Dunning Kruger, and that maybe the architecture profession is like this for a good reason -- don't bother. It's genuinely as idiotic as you think.
mannykannot 8y ago
It is heartrending to realize that they were given one last chance to step back from the abyss, when cracks appeared, but they pressed on regardless. If something happens that you don't understand, it's time to halt and reevaluate. It bugs me that FIGG (one of the contractors) appears to be threatening the professional licenses of the engineers who helped the Miami Herald's investigation, by suggesting that doing so was unethical.
- bsder 8y ago
  > It bugs me that FIGG (one of the contractors) appears to be threatening the professional licenses of the engineers who helped the Miami Herald's investigation, by suggesting that doing so was unethical. As a licensed Professional Engineer, you have to be quite careful criticizing other engineers. As long as the engineer signing off met "standard practices", he is covered and saying that he is not could get you in quite hot water. In addition, while it is certainly possible that the engineer screwed up, it is also not impossible that the concrete may have been substandard, installation instructions may not have been followed, etc. For example, in the Citibank Tower, the design was incorrect for quartering winds. However, Bethlehem Steel, the steel supplier, suggested cheaper bolted connections which made the problem worse. http://www.engineersjournal.ie/2015/12/08/citicorp-centre-tower-failure-averted/ http://www.engineersjournal.ie/2015/12/08/citicorp-centre-to... Engineering failures are often a chain. That's why the NTSB has to be allowed to do its work.
  - elefanten 8y ago
    Can you elaborate? This seems like a very perverse system. Why is criticism viewed to be so dangerous? As long as both the critic and the criticized are supporting their arguments with reasons and engaged in dialogue, the outcome should be net good for everyone.
    - mcguire 8y ago
      On one hand, speculations during an ongoing investigation do not do anything good. Ruining someone's career without actually having all of the facts is poor form. On the other, criticising a collegue for a mistake that is only obvious in retrospect is also poor sportsmanship.
Animats 8y ago
A real cable-stayed pedestrian bridge, one that's both longer and cheaper, is in Cupertino, CA, crossing I-280.[1] That was done without major disruption to I-280 traffic. There were some lane closures and two or three late night closures for a few hours. FIU built a fake one that was more expensive than a real one. [1] https://en.wikipedia.org/wiki/Don_Burnett_Bicycle-Pedestrian_Bridge https://en.wikipedia.org/wiki/Don_Burnett_Bicycle-Pedestrian...
darepublic 8y ago
I think the design of this website also had some mistakes as after a while scrolling became very laggy.
pseingatl 8y ago
1. Typical Miami. Form over substance. 2. They wouldn't have built such an elaborate bridge if the Federal government wasn't throwing money at them. Forget the deficit. 3. It's South Florida. See #1. Follow the money.
matthberg 8y ago
AvE (a rather vulgar engineer on youtube) did a good review of what he thinks went wrong, right after it collapsed: https://www.youtube.com/watch?v=ioC61QW7SHQ https://www.youtube.com/watch?v=ioC61QW7SHQ Not with all of the facts, yet interesting to see the conjecture and reasoning of trying to figure out what went wrong.
oftenwrong 8y ago
This was to be the location of the bridge: https://www.google.com/maps/place/Sweetwater,+FL/@25.7618825,-80.3745506,171a,35y,111.14h,44.97t/data=!3m1!1e3!4m5!3m4!1s0x88d9bf29221788f3:0x89dc17217f9115ee!8m2!3d25.7634334!4d-80.3731086 https://www.google.com/maps/place/Sweetwater,+FL/@25.7618825... You can see some remnants of the construction on street view.
- burfog 8y ago
  That isn't remnants. That is the bridge being built. The lower portion (deck) is there, and formwork is being built to create the middle. The satellite view is slightly newer, with a near-completed span about ready to be moved into place.
candiodari 8y ago
Baffling how this is ... wrong. I mean it's technically correct, but it's also not. It's like saying the drunk would not have crashed into that building if he took the turn in a different way. It's true ... but it's hardly the cause of something going wrong. You're just pointing out something that could have been done differently. They did the obvious thing to design the bridge, given that a hangbridge was requested. They started from a standard hang bridge and then eliminated the parts above the bridge itself, realizing that if you can just pull the cables inward the bridge will support itself like a hang bridge would. But the installable part did not look like a hangbridge, and so the contractor treated it like a non-hangbridge, that only needs support at the sides. Then, total idiocy struck. They mismeasured. The support could not actually be placed where it was planned when the bridge was designed. It needed to move ~2m to the left. And they did that, put the bridge over it, and left. So let's go over that last part again. They had a bridge that hung from a pole (the pole was just cut off at a certain point, and a horizontal tension structure put into it's place. Actually pretty cool. Also: despite the article's claims, that definitely works). Then the contractors removed the structure that supported the pole, placing a different support ... at a different place. So they interrupted the foundation of the bridge, making it discontinuous. (in their defense, with 99.9% of bridges you can do that without causing a problem, which is probably why this mistake was made) This is like interrupting a building's foundation, and having everything from the 1st floor up supported by a window. The window has some strength, of course, to hold itself up, to hold the side wall up, and generally to not be too easy to destroy, so this will work ... for a short while. And the of course the predictable thing happens : the bridge breaks in half, at almost exactly the point where the support SHOULD have been, but wasn't ... (and let's just ignore that there would have been loud cracking for a double-digit amount of seconds before the collapse, which clearly was not judged a good reason for the contractors to stop what they were doing). Who's at fault ? Well the original mistake is mismeasuring where the support should have been. I would not place blame on the designer, because he was working from faulty data. And yes, there were some different designs that would not have had this problem, but the sponsor explicitly asked for this design. Then there were a LOT of opportunities to detect this mistake, all of which were missed. And then there is the fatal decision, made by the contractors installing the bridge as far as I can tell. Oh we can't place the support here, let's just move it a bit. What could go wrong ? And they did move it. Then the bridge showed obvious signs of stress (cracks), right in front of them. Again, somehow this was missed (despite camera footage showing some worker pointing it out to some guy that looks important). They ignored those signs and just left after cleaning things up. And then ... tiny little shock overloads the weak component (which is the concrete surrounding that cable/beam thing they show, obviously NOT that cable itself). And boom. If you analyze the blame, it seems like somebody really wants the contractor's decision to just place the bridge on different supports (which, again, is not a problem with 99.9% of bridges) to be the right call. If you force that decision to be reasonable, then there's little choice but to blame the design for not allowing for that. It seems unlikely in the extreme that the design firm hadn't warned the contractors about this though.

143 points by danso 8y ago

Saw this story via an @EdwardTufte tweet: https://twitter.com/EdwardTufte/status/1007395311541682176 https://twitter.com/EdwardTufte/status/1007395311541682176 > A+ This is beautifully executed technical report by the Miami Herald, an instant classic of news reporting. Note that this report is a document not a deck. The FIU admistration loaded the bridge design down with features.

ScottBurson 8y ago
Wow, I thought it seriously needed an editor to take an axe to it. I usually like long pieces, but this just seemed repetitive.
- jacobolus 8y ago
  The way newspaper articles work, not every reader is expected to read the whole thing. They are structured to put critical information up front, so that a reader can stop whenever they lose interest without missing anything more important than what they already read, but include additional detail below for those who are more deeply interested. This leads to the same main points being repeated several times, which can be a jarring style for readers who are not used to reading newspapers. Long magazine articles are typically structured quite differently.
  - oftenwrong 8y ago
    It's known as the "inverted pyramid" style: https://en.wikipedia.org/wiki/Inverted_pyramid_(journalism) https://en.wikipedia.org/wiki/Inverted_pyramid_(journalism)
  - ScottBurson 8y ago
    Except it didn't seem like there was much more detail as I kept reading. That was my impression, anyway — I'm not inclined to reread it to see if I overlooked something.
keithpeter 8y ago
“This is not a big project," Beck said. "It’s a darn pedestrian bridge.” Quote from one of the expert engineers from OA. It is the last sentence in the article, and I think a very effective final comment. However, the article does quote two of the expert engineers as saying that the faux suspension bridge design could have been perfectly stable, had the trusses been strong enough. I was interested in the comment that had the two end pieces been in place, then the bridge may well have been fine - the plan was to swing the main bridge section into position then build the two end pieces in situ. One wonders about the design calculations for each stage of the proposed construction. I think there is a book length work around the details of the decision making process once the investigation is complete and the legal fall-out has been dealt with.
ghostly_s 8y ago
This seems a rather trite and self-serving take. 'Loaded down with features'? It seems the conclusion is there was exactly one problem, change the angle of structural members for aesthetic reasons without adequate structural analysis.

abraae 8y ago

> But FIU's bridge was designed to mimic the dramatic look of a cable-stayed bridge, where the deck is suspended from cables fanning out from a tall mast. In FIGG's design, though, the "cables" — actually metal pipes — were mostly just for show. The diagonal, v-shaped struts of the truss did the structural work. I've always found it useful to hone in on anything that is done purely for aesthetic reasons. We build a house recently. I really wanted exposed rafters, there was some complexity around insulation, and the architect responded by proposing some "faux" rafters. The idea was so revolting that it prompted more examination, which identified some mistakes. In the end, a simpler, better, cheaper solution was found that did not have faux elements in it.

deleted 8y ago
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crwalker 8y ago
Yes! Good thing you pushed back on the architect. I have a similar design philosophy that honesty is more aesthetically pleasing than deception. When designers resort to faux materials and structures, the truth still tends to peek through, resulting in an 'uncanny valley' of forms. For example: * Brickwork veneers bend in the wrong spots * Faux beams are placed in the wrong locations with the wrong joints, announcing that they can't bear a load There's certainly a place for decorative elements, just not decorative elements pretending to be something else. I spent several summers framing houses, so I'm looking forward to an opportunity to design my own house - and maybe 3D printing it.
- function_seven 8y ago
  The worst example of this are those faux shutters that seem to outnumber real ones. They're rarely wide enough to actually cover the adjacent window! https://imgur.com/a/o9Nxx6c https://imgur.com/a/o9Nxx6c EDIT: Added examples of fake garage door handles and hinges. I'm seeing that a lot more and don't understand the point.
  - seszett 8y ago

bthrm 8y ago

Isn’t this the famous “feminist” bridge?

recursive 8y ago
I've never heard of a feminist bridge, so if it is, it's not that famous.

cagenut 8y ago

This is a really good article. Amazing how a dozen+ different things combined to produce the unfortunate result. Perfect case study in there being no such thing as a singular 'root cause'.

Shank 8y ago
I concur on the quality of the article, but I would say it goes further: The Miami Herald is even suing to get public records requests filled in the interest of journalism. They’re doing an exceedingly good job at trying to get answers to tough questions.
- JauntyHatAngle 8y ago
  I am ignorant as to this whole story, but out of interest, why is it a bad thing to wait for the NTSB report? Often it is good to wait for an entire report to nail down the facts before the witch hunt should begin, is there something in this case that means this isn't the best idea?
  - danso 8y ago
    I imagine the Herald doesn't believe that the NTSB (or any authority) necessarily has the canonical and final word on things, and thus the Herald sees itself as providing an independent viewpoint/assessment. One of the undercurrent themes of this story is that, according to the herald, the construction company and FIU officials are well-connected politically. Possibly related to this is the fact that the Herald is suing the state for records related to the bridge [0]. These records were determined to be public but have so far been withheld from public release. [0] http://www.miamiherald.com/news/state/article212489364.html http://www.miamiherald.com/news/state/article212489364.html
    - JauntyHatAngle 8y ago
      So the prevailing thought is that the NTSB is delaying the documents to protect FIU officials, and not to prevent undue influence of the public before the release of the report? It certainly doesn't look good from this quoted paragraph... "Public records made and received by the Department from February 20 until the bridge collapsed on March 15 obviously were not obtained by the Department during an investigation because there had been no accident, much less an investigation into an accident,'' he wrote in a response to the FDOT motion to dismiss the lawsuit. "Florida law is clear that if an agency’s record is a public record at the time it is made or received, then that document does not lose its character as a public record if the document is later given to an investigative agency in the course of a subsequently initiated investigation." Still could be to prevent a public outcry before the facts are in, but that does seem mighty fishy...

ams6110 8y ago

There are some parallels with software. Encryption for example. Don't deviate from standard implementations unless you really know what you're doing. And even then, review it and review it again. Preferably by a separate expert.

otakucode 8y ago
The parallels do not go very far, unfortunately. When software fails, and kills people, it is rarely investigated. It's development is rarely investigated. When that is done, however, the differences widen even further. There is no degree to which software development can be done incompetently that criminal negligence charges can succeed. We saw this proven within the past decade when some of Toyotas cars engaged in "unintended acceleration." Despite the developers being denied even tools as basic as a bug tracker, and despite following only 4 out of over 90 'required' or 'suggested' coding practices advised by the automotive industry, the courts ruled that because no actual standards exist for software development, the management of the company could not be held criminally liable for the deaths they caused. This problem will re-appear. When a bridge collapses, if they found out the company building it hired the cheapest engineers right out of school, denied them access to tools or training needed to do their job, kept them removed from decisions about scheduling, ignored any concerns voiced about needing more time for proper development and testing, multiple people (the ones who wear suits) would go to prison and the company would likely be destroyed. If a few executives were put in prison over shoddily made software rushed to market, I imagine we would see changes in how software is developed of monumental proportions. But not until then, apparently. And that day doesn't seem to be coming soon. Perhaps self-driving cars will herald such a wake-up call. I know I'm certainly not trusting one until things change drastically.
- JohnJamesRambo 8y ago
  I like your viewpoint. I’d be more inclined to call programmers engineers under your proposed system.
  - otakucode 8y ago

lrn 8y ago

The Fountainhead Chapter I; Howard Roark to the Dean --- "Why do you want me to think that this is great architecture?" He pointed to the picture of the Parthenon. "That," said the Dean, "is the Parthenon!" "So it is." "I haven't the time to waste on silly questions." "All right, then." Roark got up, he took a long ruler from the desk, he walked to the picture. "Shall I tell you what's rotten about it?" "It’s the Parthenon!" said the Dean. "Yes, God damn it, the Parthenon." The ruler struck the glass over the picture. "Look, " said Roark. "The famous flutings on the the famous columns—what are they there for? To hide the joints in the wood—when columns were made of wood, only these aren't, they're marble. The triglyphs, what are they? Wood. Wooden beams, the way they had to be laid when people began to build wooden shacks. Your Greeks took marble and they made copies of their wooden structures out of it, because others had done it that way. Then your masters of the Renaissance came along and made copies in plaster of copies in marble of copies in wood. Now here we are, making copies in steel and concrete of copies in plaster of copies in marble of copies in wood. Why?"

RcouF1uZ4gsC 8y ago
Then again the Parthenon has has been around for nearly 2,500 years (finished in 432 BC), and during that time has been considered by people from all over the world one of the most beautiful buildings ever built. What building by modern architects will even be around 500 years from now, much less revered as an example of beautiful architecture?
- carapace 8y ago
  Saint Mary's Cathedral (in San Francisco) I don't say it's as beautiful as the Parthenon, and it might not last 500 years, but we moderns aren't completely shabby... https://en.wikipedia.org/wiki/Cathedral_of_Saint_Mary_of_the_Assumption_(San_Francisco,_California) https://en.wikipedia.org/wiki/Cathedral_of_Saint_Mary_of_the... > Its saddle roof is composed of eight segments of hyperbolic paraboloids, in such a fashion that the bottom horizontal cross section of the roof is a square and the top cross section is a cross. The interior is open.
  - 8y ago

VirtualAirwaves 8y ago

They spent way too much of other people's money to build something that wasn't sound. There's blame all around here.

RcouF1uZ4gsC 8y ago

> At least one said that if so, it constitutes an avoidable mistake on a bridge that should never have been so complicated. >“This is not a big project," Beck said. "It’s a darn pedestrian bridge.” There is something to be said about not over-complicating designs, whether it be in actual construction or in software.

bsder 8y ago
Many people said the same thing about the Eiffel Tower ...
- paulie_a 8y ago
  Which was built for the world's fair and was supposed to be torn down after.
stevenwoo 8y ago
They had many similar goals for a pedestrian bridge in California around 2008 or so, but they chose steel instead of concrete, a properly engineered concrete one got much more expensive bids. It's always kind of weirdly delightful to go home from a trip out of town and pass under it on I-280. https://en.wikipedia.org/wiki/Don_Burnett_Bicycle-Pedestrian_Bridge https://en.wikipedia.org/wiki/Don_Burnett_Bicycle-Pedestrian...

ebikelaw 8y ago

The article barely touches on the subject, but the bridge was really unnecessary, or necessitated only by the nonsensical urban design surrounding the university. The student housing is not only on the opposite side of a gigantic road from the campus, but it's further separated by a canal and then acre after acre of parking. If any attention had been paid, at all, ever, to the built environment this bridge would not have been needed in the first place.

jessaustin 8y ago
You have to put the acres of parking next to the buildings! Otherwise the drivers would have to walk!!1!
pseingatl 8y ago
The community was there before the university. It wasn't that long ago that it was Tamiami Airport, which has now moved even further west.
oftenwrong 8y ago
This area is like the endgame of the American suburban experiment. It is designed to be a collection of nice, isolated, suburban communities connected by a sprawling, auto-centric hellscape of oversized roads.

ndespres 8y ago

> And in order to pull off the aesthetic, the bridge's designers had to make the diagonal supports beneath them a variety of different shapes and sizes. That complication may have led the designers to miss a crucial error, independent engineers who've examined the bridge's plans believe: One of the supports was not strong enough. They aren't joking about the "variety of different shapes and sizes" for the diagonal supports. It's really incredibly ugly. In my view any "aesthetics" gained from the fake cables on the bridge are far outweighed by how goofy the whole thing looks when viewed from the side. It's really jarring, and I imagine that it would look rather cobbled together when walking over it. I also was shocked by the reported "2000 pages of calculations" that 3 different structural engineers signed off on. I have a hard time imagining that none of these experts might have said at some point, "this is a bad bridge that should not be built!" even if mathematically it could have survived magnitude 10 earthquake. Which it clearly couldn't. I'm not an engineer but it ought to be outside the ethics of an engineer's role in approving a bridge design that appears to have redundancy (the cable stays AND the diagonal supports) when the cable stays are merely a foolish aesthetic choice. Doesn't seem much different than selling a car with an airbag icon on the steering wheel when no such airbag exists. It's a false claim to structural integrity. One final thought- the PURPOSE for this bridge seems ill-conceived in the first place. Why is the campus divided by a highway to begin with?? But that's neither here nor there.

CtrlAltT5wpm 8y ago
> Why is the campus divided by a highway to begin with?? But that's neither here nor there. That's probably more circumstance than anything else. The area immediately north of the campus has a lot of residential housing, attractive to both students and employees, moreso because Miami's public transit is gawdawful; if you can walk to school/work, avoiding the traffic, that's a bonus. Additionally, the campus wasn't always the behemoth it is now. The highway they speak of is SW 8th Street, or Tamiami Trail, if memory serves. It's a main road in the area The campus was always adjacent, but only semi-recently has it begun to truly crowd the road, likely a byproduct of all the insane construction going on in the school. FIU is far from the only school spending ridiculous money on infrastructure. The school was never really plopped down next to a major highway...they both just grew, and city planning has never been the area's strong point.

ceejayoz 8y ago

> "This structure should function as more than just a path for circulation; it should be a place to be and a place to be experienced, and the FIU campus and its students must be proud of it," the document's introduction reads. "It should be a destination in its own right where community members might linger, gather, and create an urban social space — a linear park." This reads a lot like every startup that tries to convince themselves that their run-of-the-mill CRUD app is "changing the world".

JohnJamesRambo 8y ago
“Hey guys let’s go hang out on the bridge over the highway.” It is like a plaza, but a bridge! Ignore the fumes and deafening roar of traffic.
- PebblesRox 8y ago
  A successful example of this is the I-670 cap bridge in Columbus, OH. The bridge is lined with buildings so it’s hard to tell you’re even on a bridge. It has the advantage of being over a sunken highway, so there’s no grade change to deal with. https://www.google.com/search?q=the+cap+at+union+station&lr=&hl=en&prmd=minv&source=lnms&tbm=isch&sa=X&ved=0ahUKEwie1aul0NTbAhWszlkKHe1LBj4Q_AUIEigC&biw=1024&bih=653#imgrc=DGkhBEXptBzdmM https://www.google.com/search?q=the+cap+at+union+station&lr=...:
  - pseingatl 8y ago
    Or the Rialto.
deleted 8y ago
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peterwwillis 8y ago

So many concrete bridges fail for so many reasons, it's kind of crazy that we keep building them. It's much easier to inspect and repair steel than concrete, and it fails more gracefully. Also, I'm not even an engineer and I can tell you that uneven strut design would give you uneven loading on the span. Christ. Why didn't they just build a damn cable stayed bridge?! If traffic was a concern, they could have built it half cantilever, half guyed. No formwork, strong, still visually appealing, no stupid truss design, and no concrete.

WalterBright 8y ago
The struts varied in thickness according to their net loads, so their loading should have been the same.
yardie 8y ago
It was a cable stayed bridge. The bridge span was just put up. The tower and the cables were to be installed over the next few weeks. They allowed traffic under an incomplete bridge because money.
- deleted 8y ago
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- hrunt 8y ago
  It specifically was NOT a cable-stayed bridge. It was a non-redundant truss bridge with a tower and faux stays that contributed nothing to the structural capabilities of the bridge. The arrangement of the truss structure mimiced the stay angles purely for aesthetics, not for any other reason. The choice to use a single truss structure rather than a more traditional redundant set of trusses was due to the desire for a striking design. Adding the tower or cables would have done nothing to strengthen the bridge. The engineers in the article suggest that the second shorter section of the bridge to be built afterwards may have alleviated some of the stresses on the north truss beam, but the truss itself was unorthodox, so they cannot say anything for certain.
  - 8y ago

WalterBright 8y ago

"But they suggested that over-reliance on the computer models, a common pitfall in the profession, may have played into it." It's very easy to be seduced into assuming a computer model's results are correct. Computer models of critical bits should always be double-checked by a separate independent calculation. For this bridge, a simple analysis of static forces should have been sufficient for a cross-check, despite the article repeatedly implying this was a difficult/tricky computation. It is not.

hinkley 8y ago
If you did find a way to design a structure so that analysis of the static forces was not straightforward, might that be a good indication that you shouldn’t build it at all?
- antod 8y ago
  Not necessarily. Static analysis means a specific thing in structural engineering. Pin jointed frames with diagonal members (eg trusses) are easy to analyse with just geometry (statically determinate). But moment resisting frames without diagonals are not statically determinate and require more iterative calculations (usually computer modelled these days). Doesn't mean you shouldn't build them though.
  - WalterBright 8y ago
    Doing a pin joint frame static analysis is simple, and will yield a lower bound on the loads on the struts. It would serve as a good cross check on the computer model.
Mtinie 8y ago
Static force analysis only works when the materials being modeled are well known. Titanium dioxide concrete is a novel material—and, from the article’s text and subsequent research—appears to have a narrow effective range before integrity issues appear.
- 8y ago

scarejunba 8y ago

Maybe this will put paid to the nonsense people constantly spout about "real engineering". Turns out doing new things is hard. But also let's be real, you're not going to cross a 10-lane stroad, bridge or no bridge and feel like you're in 'a college town'. It was never gonna happen.

m0llusk 8y ago

Odd that there is no mention of the analysis on AvE YouTube. The support structure used was substantially different from the one planned and it was the post tensioning process that triggered the failure. It is possible that using the planned supports might have allowed the structure to endure the post tensioning procedure.

timpattinson 8y ago
AvE might work in engineering, but I don't think he's a structural PE.
- m0llusk 8y ago
  What has that got to do with anything? He got input from a range of sources including claimed structural engineers and correctly identified the point of failure during postensioning.

nkoren 8y ago

> The FIU bridge was meant to mimic the look of a cable-stayed bridge. But the 'cables' were actually steel pipes that didn't play a structural role I spent 13 years, in various capacities, studying architecture and working as an architect. Bullshit like this reminds me why I don't miss it. Vapid pasted-on "signifiers" that are not merely devoid of sensibility, but aggressively hostile towards it. Engineers fighting to coerce the pastiche into something that won't kill people. If you're not an architect and you're feeling generous -- like, maybe you're just having your daily dose of Dunning Kruger, and that maybe the architecture profession is like this for a good reason -- don't bother. It's genuinely as idiotic as you think.

mannykannot 8y ago

It is heartrending to realize that they were given one last chance to step back from the abyss, when cracks appeared, but they pressed on regardless. If something happens that you don't understand, it's time to halt and reevaluate. It bugs me that FIGG (one of the contractors) appears to be threatening the professional licenses of the engineers who helped the Miami Herald's investigation, by suggesting that doing so was unethical.

bsder 8y ago
> It bugs me that FIGG (one of the contractors) appears to be threatening the professional licenses of the engineers who helped the Miami Herald's investigation, by suggesting that doing so was unethical. As a licensed Professional Engineer, you have to be quite careful criticizing other engineers. As long as the engineer signing off met "standard practices", he is covered and saying that he is not could get you in quite hot water. In addition, while it is certainly possible that the engineer screwed up, it is also not impossible that the concrete may have been substandard, installation instructions may not have been followed, etc. For example, in the Citibank Tower, the design was incorrect for quartering winds. However, Bethlehem Steel, the steel supplier, suggested cheaper bolted connections which made the problem worse. http://www.engineersjournal.ie/2015/12/08/citicorp-centre-tower-failure-averted/ http://www.engineersjournal.ie/2015/12/08/citicorp-centre-to... Engineering failures are often a chain. That's why the NTSB has to be allowed to do its work.
- elefanten 8y ago
  Can you elaborate? This seems like a very perverse system. Why is criticism viewed to be so dangerous? As long as both the critic and the criticized are supporting their arguments with reasons and engaged in dialogue, the outcome should be net good for everyone.
  - mcguire 8y ago
    On one hand, speculations during an ongoing investigation do not do anything good. Ruining someone's career without actually having all of the facts is poor form. On the other, criticising a collegue for a mistake that is only obvious in retrospect is also poor sportsmanship.

Animats 8y ago

A real cable-stayed pedestrian bridge, one that's both longer and cheaper, is in Cupertino, CA, crossing I-280.[1] That was done without major disruption to I-280 traffic. There were some lane closures and two or three late night closures for a few hours. FIU built a fake one that was more expensive than a real one. [1] https://en.wikipedia.org/wiki/Don_Burnett_Bicycle-Pedestrian_Bridge https://en.wikipedia.org/wiki/Don_Burnett_Bicycle-Pedestrian...

darepublic 8y ago

I think the design of this website also had some mistakes as after a while scrolling became very laggy.

pseingatl 8y ago

1. Typical Miami. Form over substance. 2. They wouldn't have built such an elaborate bridge if the Federal government wasn't throwing money at them. Forget the deficit. 3. It's South Florida. See #1. Follow the money.

matthberg 8y ago

AvE (a rather vulgar engineer on youtube) did a good review of what he thinks went wrong, right after it collapsed: https://www.youtube.com/watch?v=ioC61QW7SHQ https://www.youtube.com/watch?v=ioC61QW7SHQ Not with all of the facts, yet interesting to see the conjecture and reasoning of trying to figure out what went wrong.

oftenwrong 8y ago

This was to be the location of the bridge: https://www.google.com/maps/place/Sweetwater,+FL/@25.7618825,-80.3745506,171a,35y,111.14h,44.97t/data=!3m1!1e3!4m5!3m4!1s0x88d9bf29221788f3:0x89dc17217f9115ee!8m2!3d25.7634334!4d-80.3731086 https://www.google.com/maps/place/Sweetwater,+FL/@25.7618825... You can see some remnants of the construction on street view.

burfog 8y ago
That isn't remnants. That is the bridge being built. The lower portion (deck) is there, and formwork is being built to create the middle. The satellite view is slightly newer, with a near-completed span about ready to be moved into place.

candiodari 8y ago

Baffling how this is ... wrong. I mean it's technically correct, but it's also not. It's like saying the drunk would not have crashed into that building if he took the turn in a different way. It's true ... but it's hardly the cause of something going wrong. You're just pointing out something that could have been done differently. They did the obvious thing to design the bridge, given that a hangbridge was requested. They started from a standard hang bridge and then eliminated the parts above the bridge itself, realizing that if you can just pull the cables inward the bridge will support itself like a hang bridge would. But the installable part did not look like a hangbridge, and so the contractor treated it like a non-hangbridge, that only needs support at the sides. Then, total idiocy struck. They mismeasured. The support could not actually be placed where it was planned when the bridge was designed. It needed to move ~2m to the left. And they did that, put the bridge over it, and left. So let's go over that last part again. They had a bridge that hung from a pole (the pole was just cut off at a certain point, and a horizontal tension structure put into it's place. Actually pretty cool. Also: despite the article's claims, that definitely works). Then the contractors removed the structure that supported the pole, placing a different support ... at a different place. So they interrupted the foundation of the bridge, making it discontinuous. (in their defense, with 99.9% of bridges you can do that without causing a problem, which is probably why this mistake was made) This is like interrupting a building's foundation, and having everything from the 1st floor up supported by a window. The window has some strength, of course, to hold itself up, to hold the side wall up, and generally to not be too easy to destroy, so this will work ... for a short while. And the of course the predictable thing happens : the bridge breaks in half, at almost exactly the point where the support SHOULD have been, but wasn't ... (and let's just ignore that there would have been loud cracking for a double-digit amount of seconds before the collapse, which clearly was not judged a good reason for the contractors to stop what they were doing). Who's at fault ? Well the original mistake is mismeasuring where the support should have been. I would not place blame on the designer, because he was working from faulty data. And yes, there were some different designs that would not have had this problem, but the sponsor explicitly asked for this design. Then there were a LOT of opportunities to detect this mistake, all of which were missed. And then there is the fatal decision, made by the contractors installing the bridge as far as I can tell. Oh we can't place the support here, let's just move it a bit. What could go wrong ? And they did move it. Then the bridge showed obvious signs of stress (cracks), right in front of them. Again, somehow this was missed (despite camera footage showing some worker pointing it out to some guy that looks important). They ignored those signs and just left after cleaning things up. And then ... tiny little shock overloads the weak component (which is the concrete surrounding that cable/beam thing they show, obviously NOT that cable itself). And boom. If you analyze the blame, it seems like somebody really wants the contractor's decision to just place the bridge on different supports (which, again, is not a problem with 99.9% of bridges) to be the right call. If you force that decision to be reasonable, then there's little choice but to blame the design for not allowing for that. It seems unlikely in the extreme that the design firm hadn't warned the contractors about this though.