An "instant" pedestrian bridge at Florida International University in Miami collapsed on March 15, killing a number of motorists. A 174-foot, 950-ton span of the bridge was installed on Saturday, March 10 over a busy portion of Tamiami Trail called Southwest Eighth Street. The incomplete bridge suddenly collapsed on Thursday:
The bridge gave way suddenly while the traffic light for motorists on Tamiami Trail was red, so that the concrete span fell on top of a row of stopped vehicles. A woman stopped at the light who was heading westbound said the structure fell without warning. The woman, who asked that her name not be used, said it was immediately clear to her that several people were dead.
[...] The bridge crashed across six lanes of heavily traveled Tamiami Trail, crushing a still undetermined number of cars and killing a still unclear number of people. Police on the scene said at least six people could be dead.
From an earlier article:
The rapid span installation was the result of months of preparation. The bridge's main 174-foot span was assembled by the side of the Trail while support towers were built at either end. The 950-ton span was then picked up, moved and lowered into place by special gantry cranes at the intersection of Southwest 109th Avenue in an operation that lasted several hours Saturday morning.
[...] The innovative installation method significantly reduced risks to workers, pedestrians and motorists and minimized traffic disruptions, FIU said. The architecturally distinctive, cable-supported bridge is the product of a collaboration between MCM Construction and FIGG Bridge Design, the firm responsible for the iconic Sunshine Skyway Bridge over Tampa Bay.
[more...]
The news stories about the Miami Bridge follow the common pattern of containing almost no technical information and a massive focus on the horror. The comments section to the news articles are almost equally horrific. So I started looking for civil engineering forums, ran across this one: http://www.eng-tips.com/viewthread.cfm?qid=436595 and in one of the links in one of the comments, ran into a link to the proposal from MCM and FIGG: https://facilities.fiu.edu/projects/BT_904/MCM_FIGG_Proposal_for_FIU_Pedestrian_Bridge_9-30-2015.pdf It runs 173 pages and is a mixture of marketing and an explanation of the phases of construction. Very nice renderings
I have none of the requisite knowledge to comment on the collapse, but the reading is finally interesting. I'd be interested in other people's finds as well.
https://www.nytimes.com/2018/03/17/us/florida-bridge-collapse-crack.html
Hours before the collapse of a pedestrian bridge at Florida International University on Thursday, the engineering company for the bridge met with the construction manager and representatives from the university and the Florida Department of Transportation to discuss a crack on the structure, according to a statement from the university released early Saturday.
The engineering company, Figg Bridge Engineers, delivered a technical presentation on the crack, the statement said, and "concluded there were no safety concerns and the crack did not compromise the structural integrity of the bridge."
Six vehicles remain trapped under the bridge, with four of them very difficult to extract, Maurice Kemp, deputy mayor of Miami-Dade County, said.
Original Submission #1 Original Submission #2 Original Submission #3
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Florida International University ("FIU") needed a foot bridge to cross a canal and busy street. An FIU committee selected a design without redundant structural support because they were wanting a dramatic landmark (the bridge looked like it was a cable stayed design, but it wasn't -- the faux cables were almost entirely aesthetic). The original specs had called for structural redundancy so that the failure of one structural member would not cause a collapse -- the committee ignored this requirement in favor of visual appeal.
The engineering firm selected for the bridge (FIGG) made an error in calculation for a critical member at the end of the span. The engineering firm providing peer review of the design (Louis Berger) has refused to turn over to OSHA, certain documentation regarding what it was supposed to evaluate and what it actually did. When the bridge section which had been built on the side of the road was moved into place, experienced workers became extremely worried about cracks that started appearing and made their worries known to those up the chain. A FIGG engineer examined the cracks but determined they "did not present a safety concern even though its engineers did not know what caused them — and despite clear evidence that they were growing daily." Apparently, the guidelines are that cracks deeper than a half inch are to be taken seriously and these were much deeper and growing daily -- one photo shows a crack 4" deep.
The final bridge would have two sections -- the long section over the roadway and a short section over the canal. The canal section was to be built in place and tied into the long section. Had the canal section been built first, the risk of collapse for the section over the roadway would have been reduced because it would have shored up the longer road section.
The bridge collapsed killing six and permanently disabling another.
Article regarding the OSHA report: https://www.miamiherald.com/news/local/community/miami-dade/article231428938.html
Article regarding independent engineering review with some good explanations which I, as a non-engineer, found informative: https://www.miamiherald.com/news/local/community/miami-dade/article212571434.html
Time Lapse Video of Bridge Collapse (released by FIU): https://www.youtube.com/watch?v=vrBOF2jugFM
Original Soylent item: https://soylentnews.org/article.pl?sid=18/03/19/1746219
Link to the OSHA report itself: https://www.osha.gov/doc/engineering/pdf/2019_r_03.pdf
(Score: 1, Redundant) by mendax on Monday March 19 2018, @07:37PM (7 children)
This event occurred on Thursday. Today is Monday and it's old news. I suppose the bridge's innovative method of construction justifies any tardiness; this is after all a site for those interested in technology. However, it would have been better if this were posted a few days ago.
It's really quite a simple choice: Life, Death, or Los Angeles.
(Score: -1, Troll) by Anonymous Coward on Monday March 19 2018, @08:23PM
Soylent is becoming "Slashdot's 2 day old news, 5 days old!"
(Score: 4, Interesting) by zocalo on Monday March 19 2018, @08:48PM (2 children)
UNIX? They're not even circumcised! Savages!
(Score: 3, Interesting) by FatPhil on Monday March 19 2018, @09:53PM (1 child)
Great minds discuss ideas; average minds discuss events; small minds discuss people; the smallest discuss themselves
(Score: 3, Informative) by CoolHand on Thursday March 22 2018, @02:19PM
Anyone who is capable of getting themselves made President should on no account be allowed to do the job-Douglas Adams
(Score: 1, Funny) by Anonymous Coward on Monday March 19 2018, @10:42PM
So the bridge's lifetime was shorter than the delay to post of its demise?
(Score: 5, Insightful) by requerdanos on Tuesday March 20 2018, @02:18PM (1 child)
While I don't dispute the facts, I respectfully disagree on the interpretation.
A major engineering disaster a few *years* ago would be a relatively recent thing that I, and I submit, most people, would find interesting and would appreciate discussing. Here, a major engineering disaster that happened only a few *days* ago is hundreds of times more fresh and recent. Heck, I still find the Tacoma Narrows bridge collapse from 1940 to be interesting on many levels and would have probably appreciated an article that was nothing but an opinion piece on that.
Sure, this story isn't "today's" news, but it was certainly posted as "this week's" news, and I don't believe that makes it any less interesting nor less newsworthy, especially for a site that offers as a feature, not a bug, a slower pace that's easier to keep up with.
If we demand only news of the last 24 hours, people will start demanding last 12 hours. Then last 6 hours. Then "only during the period of time when the photons leaving the event in progress are enroute to the eyes/cameras of witnesses." Madness. Madness!
I'd rather demand things that are interesting and relevant, which I believe this to be. Your position isn't any less "right" than mine, as you know, but I think that both positions have value and so wanted to share mine.
(Score: 2) by Gaaark on Tuesday March 20 2018, @04:52PM
"Heck, I still find the Tacoma Narrows bridge collapse from 1940 to be interesting on many levels"
Hell, yeah.
The same as the Roman concrete that gets better with exposure to water: 'new' news about old shit. Still fascinating.
Interesting is interesting. Just keep it coming.
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 5, Informative) by beckett on Monday March 19 2018, @07:39PM (4 children)
AvE did a short video where he explained the context of the bridge collapse, some of the engineering principles used to design this bridge, its basic structure, and how the original plans moving the bridge into place may have been compromised. [youtube.com] He is not a structural engineer, but he seems less clueless and more detailed about his analysis than most of the comments and spin i've read.
(Score: 5, Informative) by beckett on Monday March 19 2018, @07:53PM (3 children)
AvE did a followup of this initial video the next day with the feedback from the first video, and additional information, news, and photos released [youtube.com] In this video he's specifically focusing on the pylon cracking and the possibility a post tension rod in the rubble photographs that may have failed during the tensioning process.
(Score: 2) by Fluffeh on Monday March 19 2018, @09:01PM
They're great videos. I only jumped into this story to post the same links. +1
(Score: 2) by fishybell on Monday March 19 2018, @11:00PM
While these videos provide some potential insight, and possibly a root cause, let us not make any assumptions as to the actual accuracy of the claims.
It may be months before the NTSB report comes out.
(Score: 2) by MichaelDavidCrawford on Monday March 19 2018, @11:49PM
At one time prestressed concrete was widely employed.
It fell out of style when the roof of a high school gym collapsed.
Yes I Have No Bananas. [gofundme.com]
(Score: 5, Insightful) by DannyB on Monday March 19 2018, @07:49PM (5 children)
This is to be expected as more and more things are constructed the way software is written.
Programmer: can you try it one more time and see if it happens again?
Can't wait until aviation achieves the levels of reliability of computer software.
The lower I set my standards the more accomplishments I have.
(Score: 5, Insightful) by Virindi on Monday March 19 2018, @08:24PM (1 child)
Someone in the linked forum got it right:
Big problems often follow a pattern like: a system does not perform the way it is supposed to in the design. Then, instead of investigating the root cause, the symptoms are repaired without knowing how the model was wrong. Then the problem recurs later and does something worse.
This attitude to solving bugs is common in software (among people who do it badly); I've seen it a million times. Often this appears to be caused by management who see that "the system works pretty much fine, we can't waste a lot of employee hours chasing down some minor thing...just fix the problem and move on". Non-technical people managing technical projects is a recipe for doom.
(Score: 2) by Gaaark on Tuesday March 20 2018, @04:55PM
Come on, just say it: the elephant in the room is Microsoft. Amiright!
;)
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 1, Insightful) by Anonymous Coward on Monday March 19 2018, @11:17PM
From what we know now, there were cracks that had been discovered previously and weren't considered to be important structurally.
The big question though is why they were tightening cables while cars were running underneath. Especially in light of the cracks.
(Score: 4, Informative) by canopic jug on Tuesday March 20 2018, @06:41AM (1 child)
This is to be expected as more and more things are constructed the way software is written.
Preventing bad engineering and bad design has always required a lot of pushback. That pushback has been lacking of late because people have come to expect technological failure. If Bill Gates can be credited with nothing else, he has above all made bad engineering acceptable. Yes, it started with his software, but that has been only the beginning. Experience acquired in one situation is always abstracted and applied in other situations. People learning to accept bad design and bad engineering in one area become tolerant of it in others. As generations pass with new people never having seen decent design or function or owner control on computers, Bill has trained people not to push back against failure in design and implementation, first with computers, later in general.
Money is not free speech. Elections should not be auctions.
(Score: 1, Interesting) by Anonymous Coward on Tuesday March 20 2018, @11:41AM
In the middle ages, generations of architect/builders/masons created many large structures like cathedrals and castles. My understanding (from architecture school) is that the designer(s) had to stand under the big arches and domes when the construction scaffolding/shoring was removed. If your grandfather designed the structure, you (2-3 generations later) have to have a lot of confidence in his work to be in the same profession.
Time to reinstate these rules -- the owners of architect/engineering firms should have some skin in the game.
(Score: 3, Interesting) by JoeMerchant on Monday March 19 2018, @07:49PM (3 children)
... before the 950 ton span collapsed on Tamiami Trail, disrupting a major artery unexpectedly for days, killing several motorists in the process.
I caught a radio report of an e-mail from an engineer 2 days before the collapse noting cracks in the structure, at the time the report said he was not concerned for the safety of the structure, just noting the cracks.
🌻🌻 [google.com]
(Score: 2) by Snotnose on Monday March 19 2018, @07:59PM (1 child)
They say the cracks are on the north side. The video I've seen (2 of em) show the bridge failed on one side. So, did it fail where the cracks where, or on the other side of the bridge?
When the dust settled America realized it was saved by a porn star.
(Score: 1, Informative) by Anonymous Coward on Monday March 19 2018, @08:49PM
It failed on the north side.
(Score: 2, Interesting) by Anonymous Coward on Tuesday March 20 2018, @01:33AM
Death toll rises to six in Miami bridge collapse as new information emerges about contractors [wsws.org]
-- OriginalOwner_ [soylentnews.org]
(Score: 5, Interesting) by Anonymous Coward on Monday March 19 2018, @07:58PM (5 children)
The bridge span was to have 5 pipes, each 16" in diameter, connected to a tower. This was intended to change the resonant frequencies of the bridge so that there wouldn't be a feedback loop with human leg motion. The bridge was supposed to not need those pipes for support.
Concrete is tolerably strong in compression. For everything else, it is awful. A bit of pre-tensioned steel was supposed to make up for this.
They were planning to do like London Bridge in the 1600s, with shops all along the bridge! WTF. If the shops didn't suck, the resulting crowds would ruin the usefulness of the bridge as a bridge.
The bridge was required to be 20 feet wide. It was instead made 30 feet wide, but with awkward staircases that are only 15 feet wide and have right-angle turns. Most of the bridge's width was wasted.
The concrete truss was made of sharp angles. There wasn't any stress relief at the joints.
They really needed another support, and they could have done it. The road has a divider.
There is an annoying power line that seems to have compromised the design. That side of the bridge lacks a tower. Moving the bridge let them avoid using a crane near the power line.
It really should have been steel. Pure steel is great. Stone arches would have been pretty good too. Concrete sucks. Even when it isn't breaking, it's plotting to break in the future: rebar expands as it corrodes, causing modern concrete construction to fail after 50 to 100 years.
(Score: 4, Interesting) by nitehawk214 on Monday March 19 2018, @08:44PM (1 child)
Pittsburgh had a concrete bridge so shitty that they built a little bridge under it to catch all the pieces falling off.
http://gcapgh.org/wp-content/uploads/2015/11/GB_20151122_1000x500a_rsz_phassett.jpg [gcapgh.org]
It has since been replaced by a nice steel bridge.
http://www.post-gazette.com/image/2017/08/31/1140x_q90_a10-7_cTC_ca106,0,2657,1700/20170831dsGreenfieldBridgeLocal01.jpg [post-gazette.com]
"Don't you ever miss the days when you used to be nostalgic?" -Loiosh
(Score: 1) by nitehawk214 on Monday March 19 2018, @08:56PM
Note: In the picture the bridge was already under disassembly. The catcher bridge had been in place for over a decade at that point.
"Don't you ever miss the days when you used to be nostalgic?" -Loiosh
(Score: 5, Insightful) by bob_super on Monday March 19 2018, @08:57PM (1 child)
Humans know how to make concrete bridges that span over 300m long, supporting many highway lanes.
This is/was a 53m pedestrian bridge, unloaded. It should have been a piece of cake from a technology standpoint. Let's not blame the materials for the incompetence of the design and execution.
And yes, it was raw incompetence because there was obviously not enough redundancy. It's Miami, home of hurricanes and sinkholes. A bridge in Miami should be built so strong that missing half of it would not cause the rest to collapse.
Europe and Asia have many bridges that are one or two thousand years old. Whatever happened to not cutting corners, O greatest country, headed by a builder?
(Score: 4, Insightful) by Freeman on Monday March 19 2018, @10:13PM
Trump was a builder like a programmer's boss is a programmer.
Joshua 1:9 "Be strong and of a good courage; be not afraid, neither be thou dismayed: for the Lord thy God is with thee"
(Score: 0) by Anonymous Coward on Tuesday March 20 2018, @01:54AM
I saw a thing -many- years ago on PBS about how the Greeks had used iron cleats(?)[1] inserted into matching chiseled-out voids in adjacent stones to keep the stones from pulling apart.
[1] Like a double-ended T.
Modern guys had come behind them and used bare iron to replace some of those and, as you say, the damned things swelled up and split the stones.
(The original guys had dipped theirs into molten lead).
It's sad that nobody thinks beyond next week these days.
-- OriginalOwner_ [soylentnews.org]
(Score: 4, Interesting) by Hartree on Monday March 19 2018, @08:57PM (1 child)
"The innovative installation method significantly reduced risks to workers, pedestrians and motorists and minimized traffic disruptions"
I wonder how incredibly risky installing it the old fashioned way would have been.
(Score: 2) by fraxinus-tree on Tuesday March 20 2018, @07:45AM
The old fashioned way is not actually that much different. It consists of bringing smaller parts and spending more time assembling them onsite. The safety gain of the new technology comes from doing more of the work in a controlled factory environment AND closing a busy road for less time.
Closing a road means a lot of people driving more miles on more congested routes, after getting less sleep.
(Score: 1, Funny) by Anonymous Coward on Monday March 19 2018, @09:13PM (1 child)
All the red tape Dems caused this. If we could build a bridge with less red tape we would not waste money on tape and use it for more structurally sound materials.
(Score: 1) by khallow on Monday March 19 2018, @09:35PM
So started by Obama and failing to follow regulations on such projects ... sounds like the Democrats' fault, right? But then we have this:
It'll be interesting to see how this bridge project was expedited and whether they cut some safety or engineering regulations in order to let the (TIGER) pork flow.
(Score: 2) by Runaway1956 on Tuesday March 20 2018, @02:30AM (2 children)
The whole concept of frefabricating and prestressing concrete is about saving money. That's it in a nutshell. Concrete is expensive. Engineers and contractors want to save all the concrete possible, because an extra yard of concrete eats into their profit.
Anyone who has worked in industrial construction has seen these things damaged during installation. As noted several times, concrete is brittle. When you start moving a concrete structure around, you can expect some impacts, and some bending, flexing, or warping.
I just never learned to trust prefab concrete. It's much better to pour in place, and to not worry excessively about some extra yards of concrete.
Watching the sales pitch video, it's obvious that there are suspension cables supporting a portion of the bridge's weight. There are no suspension cables in sight, at any stage during construction. Just how many field modifications were made? When a standard suspension bridge is built, it is obvious to all that the suspension cables are integral to the bridge's design. In this case, the sales video shows suspension cables, but we don't even see attachment points for any such cables. We see no tower or platform from which to hang any suspension cables. Who authorized the changes, and when?
Nothing about this bridge, or it's construction inspires confidence. Seriously - nothing.
We can all be happy that we weren't involved at any stage in this project.
(Score: 0) by Anonymous Coward on Tuesday March 20 2018, @05:29PM
The "cables" you mention were not structural members of this bridge. It was a truss bridge, not a suspension or cable-stayed bridge. Apparently they would have served to dampen vibrations but were not essential to support the design load of this bridge.
Obviously a serious fuckup happened somewhere but I am sure the plan was entirely reasonable to bridge experts. The final investigation results should be interesting.
(Score: 0) by Anonymous Coward on Tuesday March 20 2018, @06:37PM
"There are no suspension cables in sight, at any stage during construction. Just how many field modifications were made? "
This sounds like projects i've been on. Incompetent morons trying to get people killed.
(Score: 2, Interesting) by jmorris on Tuesday March 20 2018, @02:31AM (6 children)
Oh come on, if nobody else is gonna say it after this many hours I have to. Diversity and affirmative action kills.
Well, if this is art, I don't get it. :) Can't say we should be funding it either. Lets let the NEA piss away money on art[1] and let us build functional infrastructure.
If the price of affirmative action is morons who can't manage to build a simple pedestrian bridge without it falling down, combined with being stupid enough to doing the work while eight lanes of traffic are running under it in the middle of the damned day, is it time to ask if the price of feelz and virtue signaling is too high? Or do we continue until the body count grows into the thousands when something even more important goes splat?
[1] OK, i don't support the NEA either, but if money is to be wasted on art nobody likes, let it waste space in galleries instead of making unsafe infrastructure.
(Score: 4, Insightful) by Magic Oddball on Tuesday March 20 2018, @06:47AM (2 children)
While I think that the statement about women being better at art is a load of horseshit, a few quick searches didn't turn up anything indicating that affirmative action was involved in choosing the companies or who they hired. Unless you're leaping to the conclusion that any females in technical positions must have only been hired due to affirmative action, which would be an even larger pile of idiocy than the quote you cited.
(Score: 0) by Anonymous Coward on Tuesday March 20 2018, @07:36AM
I thought the distribution of workers for this company favored women.
(Score: 2) by jmorris on Tuesday March 20 2018, @08:09PM
But that IS the point, isn't it? Isn't it right there in the definition of Affirmative Action? That we should hire people based on pretty much everything that isn't directly a factor in the only thing that should matter, qualification to do the actual job? By definition, when you aren't hiring based on skill you aren't getting the best. The advocates reassure us that while we might not be getting "the best" the applicants who get the jobs instead are at least "minimally qualified" but we keep seeing that even that is not true. But even if true, a nation is assured of not being great if all of the important tasks are taken from the best and given to "minimally qualified" people. We used to want the best people put in positions where they could make maximum use of their talents so we, and the whole damned world, benefited from the superior skills of the few out on the edge of the Bell Curve.
It is obvious that engineering was not the best use of this woman's natural talents. Meanwhile someone whose natural talents and inclinations are toward engineering is forced to work at a task he / she is less suited to. Lose / Lose.
(Score: 4, Insightful) by PiMuNu on Tuesday March 20 2018, @02:01PM (1 child)
When a man builds a crap bridge, it is because he is an idiot. When a woman does it, it is because she is a woman.
i.e. just because one woman is an idiot, doesn't mean all women are idiots.
(Score: 2) by requerdanos on Tuesday March 20 2018, @02:21PM
Troll mod was a misclick for which I apologize. Was going for "Interesting".
(Score: 3, Touché) by Osamabobama on Tuesday March 20 2018, @04:57PM
I expected the footnote to reference Piss Christ [wikipedia.org]. Because it didn't, I felt the need to add it.
Appended to the end of comments you post. Max: 120 chars.