Talk:Florida International University pedestrian bridge collapse

Location
Based on the news reports, the bridge appears to have been located at 25.761208, -80.372766. 216.81.81.81 (talk) 19:16, 15 March 2018 (UTC)

Construction reporting

 * news.fiu.edu/2018/03/community-gathers-to-watch-950-ton-bridge-move-across-southwest-8th-street/120395

216.81.81.81 (talk) 19:19, 15 March 2018 (UTC)

It appears from this and similar articles the official name of the bridge is UniversityCity Pedestrian Bridge. It may be interesting to note, and likely to be addressed later, the design shows it to be a cable-supported bridge, and those were not yet installed.--KMJKWhite (talk) 19:41, 15 March 2018 (UTC)
 * http://www.miamiherald.com/news/local/community/miami-dade/west-miami-dade/article204506084.html
 * It is not uncommon for what appear to be structural elements to actually be largely ornamental. It is possible that the bridge was designed for the deck and roof to support the bridge alone and the cable supports and center column acting as purely architectural features. That being said, even as an architectural feature it would have added to the safety factor of the completed bridge.Danbert8 (talk) 14:04, 16 March 2018 (UTC)
 * Please provide a reliable source to support the odd claim that the cables and tower were merely decorative or do not post such speculation. Edison (talk) 15:15, 16 March 2018 (UTC)
 * Unfortunately pretty much all information regarding the design of the bridge has been removed from public access and probably will be until it is released as part of the accident investigation. I have changed my post to say "possible" instead of "likely". However, the fact that the bridge section was installed without the center column and cable supports in place is a strong indication that the bridge deck was designed to be self supporting, even if that design may have been insufficient. Note that I haven't tried to add this comment to the main article. This is the talk page, and I was responding to the "interesting to note" comment.Danbert8 (talk) 15:27, 16 March 2018 (UTC)
 * I am quite certain that the term "cable-supported bridge" means exactly what the term implies. While certainly supporting towers and cables often appear decorative, they still function as principal engineering support. The architectural community appears to have mixed opinions whether tower and cables are required at this early stage of construction. However, there is no doubt they are essential prior to opening such bridges to the public. See Miami bridge that collapsed lifted into place without suspension cables, support tower.KMJKWhite (talk) 17:54, 16 March 2018 (UTC)
 * "Cable-supported bridge" is not a sourced technical term. It is a visual observation. My visual assessment of the structure probably differs from yours. But Wikipedia is not for original research, so my PE in Civil Engineering doesn't count as a source. However, this report on the bridge says that the tower and cables provide extra stiffness for pedestrian loads https://facilities.fiu.edu/projects/BT_904/MCM_FIGG_Proposal_for_FIU_Pedestrian_Bridge_9-30-2015.pdf. See page 17. They are in no way essential or they wouldn't put up the sections without them in place or temporary supports until it was constructed. They are simply to reduce undulation of the structure for people walking. Despite the visual look, a more accurate technical description of this bridge is a cable supplemented truss bridge.Danbert8 (talk) 11:46, 18 March 2018 (UTC)
 * If you look in section 6.3 of that Technical Proposal document the annotations on the picture of the bridge are very explicit that the tower & struts are not required for the bridge to meet its design load - they are there purely to alter the resonant frequencies of the bridges oscillation modes for pedestrian comfort. UphillPhil (talk) 13:33, 18 March 2018 (UTC)
 * Also, according to that document they’re not cables at all, but hollow steel tubes ("stay pipes" in the annotation I mentioned). UphillPhil (talk) 13:46, 18 March 2018 (UTC)

Reminder on sourcing
Just a reminder that editors should always take particular care with RS on these sort of late breaking news stories. Many nominal RS can produce question work. For example my local paper here in Auckland, NZ (which includes a lot of Daily Mail content and even their own content can be a bit iffy) says the construction company took their website down. I doubt they know this. What happens in a lot of these cases is if the site isn't behind some sort of competent CDN like CloudFlare, the website is effectively DDoSed. Interest from the public is two orders of magnitude higher than normal, or maybe even more and it simply can't handle it. For a fairly unknown construction company (or other such things) this often isn't that hard. Maybe the website was at peaks, only getting a a few ten hits a minute before. Suddenly it's getting 1000 or more. (Stuff on their webpage, and the company tweeting a story on the bridge 3 hours or so before it collapsed probably helped make them viral.) Nil Einne (talk) 20:25, 15 March 2018 (UTC)

Split?
Should we split the article into 2 separate projects? One for the bridge and one for the incidence of collapse? — Preceding unsigned comment added by Xinbenlv (talk • contribs) 22:22, 15 March 2018 (UTC)
 * The bridge itself isn't notable enough to warrant a separate article. See similar bridge incidents (e.g. I-5 Skagit River Bridge collapse) where the bridge's background is integrated into the article.  Sounder Bruce  22:30, 15 March 2018 (UTC)

Stress Test
It seems dubious to state "bridge was undergoing stress test at the time of collapse". One of the articles states company officials declined to comment on whether the bridge had undergone a stress test, and the other article states "workers at the scene said it was undergoing some sort of stress test" (emphasis added). Sounds an awful lot like hearsay to me, so we should probably refrain from mentioning this until an authoritative source states this. — Preceding unsigned comment added by Closetsingle (talk • contribs)
 * I've removed it twice. The source is reporting hearsay and speculation, it has no place in the article until something comes from a clearly authoritative source. Wikipedia doesn't publish speculation just because somebody said it somewhere.  Acroterion   (talk)   00:32, 16 March 2018 (UTC)
 * A bystander coming to the conclusion that the bridge collapsed because a blue cable fell on a blue box doesn't measure up to Wikipedia sourcing requirements.  Acroterion   (talk)   00:35, 16 March 2018 (UTC)
 * What part of "Congressman confirms that a stress test was underway at the time of the collapse" is unclear to you?--2600:8800:FF0E:1200:C57:B925:112F:96D (talk) 00:58, 16 March 2018 (UTC)
 * What part of "avoid speculation" do you not understand? Until there is specific information on what the testing involved, leave it out, congressman or not. Unless the congressman is a qualified engineer with specific detailed knowledge of the project it means nothing.. Testing is a nearly constant process on projects of this kind, it would be unusual if there was none happening. Don't report speculation in Wikipedia's voice Acroterion   (talk)   01:03, 16 March 2018 (UTC)
 * This Miami Herald article is headlined "Stress test may have contributed to collapse of FIU pedestrian bridge," but the actual article amounts to theorizing and speculation, and the most significant part of it is devoted to speculation about camber adjustment, which isn't testing at all, regardless of what the mayor and congressman think. We really need to wait until there's more definitive information from authoritative sources.   Acroterion   (talk)   01:38, 16 March 2018 (UTC)
 * I've removed it again. Just because it's been circulated via news agency in a headline doesn't make it true. The Miami Herald has a measured article on the subject of testing and adjustment, and avoids making claims that a number of editors have tried to insert from superficial sourcing.  Acroterion   (talk)   12:08, 16 March 2018 (UTC)
 * Early on in the aftermath pf an event such as this lots of things get said which are later shown to be incorrect.That does not mean we cannot report on such pronouncements. I suggest that statements about whether a stress test was ongoing just be put in the article along with clear attribution as to who said it, such as Rubio or the college president. We are saying merely that they said it, not that it is objectively true. The picture will become clearer and a more definitive statement will be available when investigations are complete months or years in the future. We are not speculating about the true cause when we report what Rubio says, we are just reporting what named authorities are saying, and that satisfies verifiability. It is inappropriate for some anonymous editor here to announce that he knows better than Rubio or the college president what the cause was, so we must not report what they said.  Edison (talk) 15:23, 16 March 2018 (UTC)
 * I agree. Early in the investigation process we should not confidently report speculation in Wikipedia's voice, still less if it's largely based on headlines. We can certainly state that "early speculation centered on testing or adjustments."  Acroterion   (talk)   16:12, 16 March 2018 (UTC)

At a March 16 NTSB press briefing, one of the NTSB investigators presented factual information about the bridge. The briefing was uploaded to YouTube (he is introduced at 1:07 and speaks for a couple minutes) and, at 1:55, he says: "Construction crews were working at the diagonal at this location right here [pointing to the northmost diagonal, which is not aligned with the to-be-installed cables] at the north end of the structure at the time of the collapse. The construction crews were applying post-tensioning force that is designed to strengthen the diagonal member." I'm editing the schematic to highlight the diagonal that was being tensioned at the time of the collapse. As for the cable tower and cables, he later states (at 5:45): "As I understand it, these were cosmetic, they were not structural members." AHeneen (talk) 05:02, 19 March 2018 (UTC)

Name of the bridge
This bridge is called "FIU-Sweetwater UniversityCity Bridge" not "FIU-Sweetwater University City Bridge". See CBS NEWS, FIU News, CNN, Miami New Times.―― Phoenix7777 (talk) 02:37, 16 March 2018 (UTC)

FIU-Sweetwater UniversityCity Prosperity Project Pedestrian Bridge

 * "UniversityCity Prosperity Project bridge" — News at FIU
 * "UniversityCity Prosperity Project bridge" — News at FIU
 * "UniversityCity Prosperity Project bridge" — News at FIU

TV

 * 69.181.23.220 (talk) 09:46, 16 March 2018 (UTC)
 * 69.181.23.220 (talk) 09:46, 16 March 2018 (UTC)
 * 69.181.23.220 (talk) 09:46, 16 March 2018 (UTC)
 * 69.181.23.220 (talk) 09:46, 16 March 2018 (UTC)
 * 69.181.23.220 (talk) 09:46, 16 March 2018 (UTC)
 * 69.181.23.220 (talk) 09:46, 16 March 2018 (UTC)

Title:
Current:
 * Florida International University pedestrian bridge collapse

New:
 * Florida International University bridge collapse

Alternate:
 * FIU–Sweetwater UniversityCity Bridge collapse

The bridge's name does not include "pedestrian" in it at all, thus the title of the article should not include it. The text of the article can say it's a pedestrian bridge. I've also seen the bridge referred to as "FIU–Sweetwater UniversityCity Bridge". Is this the official title? Harizotoh9 (talk) 14:24, 16 March 2018 (UTC)

Lanes of traffic
The article says that the bridge spanned six lanes of traffic. Everything that I have seen says "eight lanes". Please change, if appropriate. Thanks. 32.209.55.38 (talk) 15:03, 16 March 2018 (UTC)


 * It appears to be 6 through lanes and three turn lanes ( two left one right ), just looking at the google satellite photo.

Gjxj (talk) 15:33, 16 March 2018 (UTC)


 * I think Gjxj is looking at the wrong side of the intersection. The pedestrian bridge is located on the other side of 109th from the water crossing bridge shown in the satellite photos on Google Maps. The bridge crossed 7 through lanes and 1 left turn lane on the west side of the intersection. "Eight lanes" seems to be the appropriate description.Danbert8 (talk) 15:36, 16 March 2018 (UTC)

Sorry I just counted wrong.. only one left turn lane, so 8 lanes. If you follow the coordinate link to google maps it puts the pin in the correct spot west of 109th. Gjxj (talk) 15:49, 16 March 2018 (UTC)


 * Thanks. If it is indeed "eight lanes", can someone please correct that?   Thanks.   32.209.55.38 (talk) 18:29, 16 March 2018 (UTC)

done Gjxj (talk) 00:57, 17 March 2018 (UTC)


 * Thanks! 32.209.55.38 (talk) 04:52, 17 March 2018 (UTC)

links to actual design
if anyone has links to renditions of the actual final design, that would be a valuable addition the the article. ( All that I've seen are artist's renditions that do not at all resemble what was actually being built ) Gjxj (talk) 15:37, 16 March 2018 (UTC)

The artist renderings are for the final design. The bridge was only partially completed. Harizotoh9 (talk) 16:12, 16 March 2018 (UTC)

I found it. The rendering in the FIU news 3/14/2018 article looks right. There are other renderings floating about that do not show the truss structure. Gjxj (talk) 23:40, 16 March 2018 (UTC) https://news.fiu.edu/wp-content/uploads/unnamed-3-2-400x267.jpg — Preceding unsigned comment added by Gjxj (talk • contribs) 23:42, 16 March 2018 (UTC)

Lots of original research and amateur engineer opinion has crept into the article. Will work on it later to remove unsourced statements abut the structure. Here is one source that says the tower and cables would have helped support the vertical load near the failure point, as well as stiffening the structure, Someone on this page claimed the tower and cables were only for visual appeal: http://www.miamiherald.com/news/local/community/miami-dade/article205704039.html Edison (talk) 13:48, 18 March 2018 (UTC)
 * This source quotes unnamed "experts" saying the stays may have provided redundancy and is more conjecture than any amateur engineer Wikipedia editor. The named engineer who claims the pylon could have increased factor of safety has a pretty big caveat in there about not being a bridge expert. The tower and the "cables" (actually pipes) were definitely not designed to hold the span or provide redundancy and the bridge was certainly intended to operate without them since it was being installed that way according to the original design documents. Including any reference to the tower or stays possibly preventing or slowing this collapse is highly speculative unless sourced by an engineer familiar with the design. In fact, had they been present they likely would have caused more damage as the tower was pulled down by the extremely heavy truss section. Also, for reference some of the "amateur engineer opinion" on Wikipedia is from Professional Engineers... It's still original research which is why I keep mine to the talk page, not the main page. If it were me, I would keep any and all speculation to the cause out of the main article until it is released by FDOT, NTSB, ASCE, the design firm, or the construction firm. Local and national news sources are not very reliable when it comes to technical topics.Danbert8 (talk) 12:22, 19 March 2018 (UTC)
 * Wikipedia had an infamous episode where a user claimed to be a professor and browbeat other users into deferring to his expertise until it was revealed he had not even earned an undergrad degree, So the only advantage a professional engineer has in a dispute is that he can pull out textbooks, cite journal articles, or cite handbooks to verify something. So opinions of editors here don’t count for more because they say they have credentials, degrees, licenses or experience when an opinion gets cited in the article for needing a reference to a reliable source, if the text is something open to disputed. Unfortunately that may rub experts the wrong way, so I intend no offense. An article like this needs all the expert help we can get, especially in discussing what is or is not a reliable source. Edison (talk) 20:15, 19 March 2018 (UTC)
 * I agree completely Edison. I don't think any of my statements have any weight due to my PE and there is no way to verify my credentials. That's why I haven't done any edits on the main page. My goal is to look at the talk page and add opinions and clarifications into the debate about what to include and what is reliable. I'm trying to keep the page and talk clear of the idea that this collapse was in any way related to the lack of tower and pipe stay supports in place. It's easier now that the NTSB briefing has a public statement about the tower being largely cosmetic.Danbert8 (talk) 16:30, 20 March 2018 (UTC)
 * The NTSB is hardly authoritative in this regard, and their preliminary reports are often riddled with errors. BoKu (talk) 02:46, 22 March 2018 (UTC)

Cracking
This report came through just now concerning observed cracking near the north end. As with the reports of testing, it should be reported as something that was observed, without drawing conclusions in Wikipedia's voice. As the article notes, cracking is not unusual in concrete construction - a certain amount is expected and designed for as concrete cures and shrinks. Whether it was in this case unusual or whether it played a role in the collapse remains to be seen.  Acroterion   (talk)   01:07, 17 March 2018 (UTC)
 * The local news has--Ozzie10aaaa (talk) 01:13, 17 March 2018 (UTC)


 * The image which currently accompanies the Cracking section is incorrect. The entire section to the right of the pylon collapsed. An earlier image described this point correctly. The chord shown in red was acting as a strut after the long section of deck was installed. Gregorydavid (talk) 05:59, 19 March 2018 (UTC)
 * I see the image I am referring to is actually in the Collapse section above which is otherwise currently empty. Gregorydavid (talk) 06:36, 19 March 2018 (UTC)

Photo
As the previous photo was copyrighted and under SD, it can't be used here. Do you think uploading a fair use photo is necessary here? I did it once in IRC3704, but get deleted by someone else, stating that there's no need of fair use photo.

KTT 廣九直通車 (talk) 03:19, 17 March 2018 (UTC)
 * Fair use wouldn't work here, especially with government bodies producing photos (PD-USGov is a blessing). Plenty of images available on Flikr too, just need to ask for permission and verify that the images aren't copied from twitter. Not sure how close people are allowed to the scene but I could probably snap a photo myself since it's down the street from me. I suspect we'll get some very useful pictures from the NTSB in due time though. ~ Cyclonebiskit (chat) 04:28, 17 March 2018 (UTC)

Found some photos on Commons from NTSB, thx! 廣九直通車 (talk) 04:33, 17 March 2018 (UTC)
 * The NTSB flickr page has many public domain photos of the collapse. AHeneen (talk) 06:03, 17 March 2018 (UTC)
 * Also, most works made by Florida state & local government employees are free of copyright. Note that universities and the Fla. Dept. of Transportation are agencies allowed to hold copyright and state/local government agencies may use copyrighted photos of third parties (like an image of a proposed design being included in a project proposal). However, most state & local government agencies otherwise related to the rescue and investigation aren't allowed (by state law) to hold copyright so their works are public domain. See Copyright status of work by the Florida government and the Commons template Template:PD-FLGov. AHeneen (talk) 04:23, 19 March 2018 (UTC)

car extraction
sent to coroner Miami Dade--Ozzie10aaaa (talk) 15:59, 17 March 2018 (UTC)

Costs confusion
At this moment, the first paragraph of the Background section contains these two sentences: "The $14.2 million project was funded with a $19.4 million Transportation Investment Generating Economic Recovery (TIGER) grant from the United States Department of Transportation in 2013, along with state agencies. The bridge itself cost $9 million to construct."

Why was a bridge costing $9 million granted $14.2—or $19.4— million to build? Are these amounts contradictory? Or do they hint at some complexity? —EncMstr (talk) 21:01, 17 March 2018 (UTC)
 * The bridge cost is only a portion of the project and probably doesn't include stairways, ornamental stuff around the bridge, roadway repair after construction, sidewalks, landscaping etc. Still ridiculously expensive for a pedestrian bridge paid for by taxpayers...Danbert8 (talk) 11:50, 18 March 2018 (UTC)
 * Major public works often get expensive far beyond the basic cost of getting the function achieved. See Tweed Courthouse. Edison (talk) 20:02, 18 March 2018 (UTC)
 * As already mentioned, the grant amount cited probably included more than just the bridge (eg. adding sidewalks, modifying the roads under/adjacent to the bridge, research & development, etc.). That said, a USDoT overview (see pg. 18) of TIGER grants awarded in 2013 says the "UniversityCity Prosperity Project"—which included the bridge, but also infrastructure, streetscaping, and transit improvements in the project area—was awarded $11,397,120 (of an estimated $123.8 million total project cost). Here's an FIU press release. AHeneen (talk) 04:13, 19 March 2018 (UTC)

perhaps the article should say "funded with part of.." Gjxj (talk) 11:50, 25 March 2018 (UTC)

Accelerated Bridge Construction University Transportation Center
Ironically, FIU was home to the federally-funded Accelerated Bridge Construction University Transportation Center, and is a leader in the technique. I added this, but you might decide that it should be more prominent -- maybe even the lead. --Nbauman (talk) 03:09, 18 March 2018 (UTC)

The last paragraph in the Background section could be misleading. The ABC method is being reported, or alluded to, as the culprit by various news outlets. However, an official report citing the root cause has yet to be published. All that is being reported about the root cause of the collapse at present is conjecture. The official investigation needs to take place and a report needs to come out from an official investigating agency (Probably the National Transportation Safety Board) citing the root cause of the collapse, before any link between the collapse and the ABC method can be determined. Also this is not the first project to use the ABC method. Spoonlesscorey (talk) 13:17, 18 March 2018 (UTC)


 * While I agree that the article shouldn't contain speculation about the cause until reliable sources have enough time analyze the situation to draw reliable conclusions (many news articles interview engineers that don't seem to have a good grasp of what happened) and also that the ABC method in general probably wasn't a culprit...the article can (and should) contain reliable factual information that may suggest or highlight a cause, especially since it will take a long time (probably over a year) for investigators to release a report on the causes. How such information is presented in the article is a balancing act between presenting reliable facts/theories and presenting inappropriate original research or inappropriate speculation. Also, if there's doubt about whether something belongs in an article, it should be discussed on this talk page rather than repeatedly deleted.
 * As for ABC, Wired cited a Federal Highway Administration factsheet that over 800 ABC bridges have been built since 2010, but that statistic referred to bridges using structural components that were manufactured off-site or adjacent to the bridge (excluding geotextile blocks) and not the specific method used in the FIU bridge were an entire span was built next to its permanent location and then moved into place. Still, a lot of bridges have been built using ABC methods both in the US and abroad. I've seen many timelapses on YouTube of bridges in Europe built like the FIU span (next to permanent location then moved into place). Since ABC has become a buzzword in the media, I think it deserves to be addressed in the article, but placing blame on the method shouldn't be done. AHeneen (talk) 03:50, 19 March 2018 (UTC)


 * In light of recent edits, and after re-reading, I think the line


 * The ABC method was touted to "...significantly reduce the risk to workers, walkers, drivers and minimize traffic disruptions for construction."


 * can and should be removed (or at least rephrased and placed elsewhere). The phrasing "was touted" is the part I really take issue with. It implies that the ABC method does none of the things listed in the quote. Which isn't true, the method is established and hasn't been abandoned as a result of the collapse. If we change "was touted" to something like "is known" or something along those lines, the sentence becomes clumsy and feels more like extra out of place information. There is plenty of info about the ABC method elsewhere on this page, and if someone is really interested they can go to the page for accelerated bridge construction.Spoonlesscorey (talk) 15:52, 19 March 2018 (UTC)
 * This edit deleted reference to FIU's expertise in ABC, and FIU's Accelerated Bridge Construction University Transportation Center, without giving a reason in the Edit summary or in Talk. That reason alone is sufficient to revert it, and I am doing so.
 * I also believe that FIU's expertise is significant to the story, because many WP:RS have included it in their stories. For that reason also, it should stay in.
 * This is factual information that readers could reasonably want to know (which is why it was in so many WP:RS). An editor's decision that it might be misleading, and so should be deleted, is WP:OR. If you can find a WP:RS to add to the entry to make the same point, that would be acceptable. --Nbauman (talk) 16:38, 19 March 2018 (UTC)

Struts and ties?
Can we please check that the terminology is used consistently here. Early on the two structures are introduced and described, with the tensioned chords described as 'ties' and the compressed chords as 'struts'. If we can get a photo (fair use should be possible, as the bridge is no longer there to photograph) or else draw it, the tensioned ties are in line with the cable stays, which might be a useful clarification.

Last para, §Bridge construction and design states, " The bridge is fracture critical with each strut being a potential single point of failure. " Is this for a strut, or a member in general (i.e. ties failing too)? If the bridge regresses to a Vierendeel truss after a failure, would that be from loss of any member, or just from one of the tensioned ties? If these claims are broadly applicable to any of the members, then they're contradictory.

Last para, §Reports of precollapse cracking, refers to the pre-tensioning tendon being in a 'diagonal strut'. Can we confirm (and make clear in the text) that this was indeed a strut, i.e. a compressed member. It might be worth further noting that even though this member would be in compression anyway, it was being pre-tensioned. Andy Dingley (talk) 14:26, 19 March 2018 (UTC)


 * I re-inserted the schematic and caption. I can't comment on member/strut/tie terminology, but according to an NTSB investigator during the press briefing on March 16, the red member (term he used) was being post-tensioned, not pre-tensioned. AHeneen (talk) 18:01, 19 March 2018 (UTC)


 * To clarify, all of the members in this structure are post-tensioned, not pre-tensioned. As far as which members are struts and ties is a bit moot and definitely not relevant to the discussion. All of the members are in both tension (the steel reinforcements) and compression (the concrete). Overall, the net force on the beam cross section may be tension or compression, but in a truss that is subject to change with loading and support. One of the reasons additional adjustments were being made on the members prior to the collapse is that the diagonal member that failed was in net tension in transport and was under net compression in the installed position and the post-tensioned reinforcements had to be adjusted to compensate.Danbert8 (talk) 16:39, 20 March 2018 (UTC)

IP POV push?
I'm concerned about these edits:   (If I'd been watching here earlier I'd have reverted by now). They're big unexplained deletions, and the insertion of a 'fringe' theory (since removed). Red flags all round. Andy Dingley (talk) 14:26, 19 March 2018 (UTC)

Original research issues
The section "Bridge construction and design" seems to still have some original research and/or uncited/unsupported statements. Specifically the paragraphs starting "Concrete by itself is very weak..." and "The bridge spans used a novel concrete..." -- William Graham talk 01:39, 20 March 2018 (UTC)
 * Agreed. We don't need to summarize reinforced concrete design principals in the article, nor to we need to make erroneous claims that the bridge was made of concrete to keep from being "bouncy." Reinforced concrete can be far more flexible than steel structures, or totally rigid. It's all in the way it's designed and to what deflection criteria. The novel concrete formulation is written in a similarly inappropriate informal style.  Acroterion   (talk)   01:56, 20 March 2018 (UTC)
 * I've adjusted the wording to clean up informalities, scale back wordiness, and remove some rather speculative or erroneous statements about the design intent.  Acroterion   (talk)   02:20, 20 March 2018 (UTC)

Lead Rewrite
I made a good faith attempt to produce a Lead Section that meets the Wikipedia standards well enough to justify my removal of the Needs Lead Rewrite tag. I removed all of the technical jargon, e.g. "post-tension rod adjustment," "interface shear capacity," "nodal point," none of which are comprehensible by the layperson. I tried to state in everyday English what happened, in enough detail that the reader would get the picture, leaving technically detailed descriptions for later in the body of the article. Nick Beeson (talk) 14:01, 8 July 2021 (UTC)

Importance of cold joints and incomplete analysis of forces in partially-built structure
Can someone who has time to watch for reversions please improve this article? After reading it, I still couldn't understand why the collapse occurred. "They calculated forces improperly" is not specific. Did they drop a decimal point, or mess up unit conversions like with the Mars Climate Orbiter? This article is helpful: https://www.newcivilengineer.com/latest/fiu-bridge-collapse-lessons-learnt-three-years-since-florida-tragedy-15-03-2021/

"Construction decisions to cast the structure with cold joints at the base of diagonals". This Wikipedia has the word "cold joint", but it links to welding and is followed by "(node)". If you look up what a cold joint is, this is not what it means for concrete: it's a weak plane due to a pause in laying concrete, which is important to the explanation that truss 11 slid along the deck or 'punched through' the joint.

Link also says, 'Post-collapse, Louis Berger confirmed to NTSB investigators that [a finite element analysis software program] analysed the design as one structure in its completed state. It only analysed the design for the completed structure and not for its various construction phases.' So, the calculations for the completed bridge were correct. 73.65.167.168 (talk) 01:16, 18 August 2022 (UTC)


 * "Why the collapse occurred" is a fair question (and much broader than the one you're specifically asking). Like most such disasters, there are many reasons why it happened.


 * Firstly, the basic design was simply flawed. Concrete is a totally inappropriate material for a truss bridge (which is why there are no concrete truss bridges in the world).  A fundamental requirement of a truss is the ability to transfer compression and tension forces between the various structural elements, and concrete has exceedingly little ability to transfer forces.  Additionally the design process was flawed: the bridge was designed to "look good", not to be functionally good, and when appearance is the prime criteria the resulting engineering is rarely good.


 * Secondly, the detailed design was flawed. The engineering team was not well experienced, and made fundamental errors in calculating the stresses in the structure (in part because, in order to make the bridge look impressive, each of the triangle structures in the truss had different angles).  This led to a drastic under-estimate of the compression forces which had to be transfered between the last diagonal (#11) and the deck of the bridge.


 * Thirdly, the construction process was flawed. To maximize the transfer of forces in a concrete structure, it needs to be cast as one piece.  That was not done here, instead the deck was cast and allowed to cure, and then the diagonals were cast on top.  To help transfer stress between two parts cast at different times, the surface of the first should have been ground rough (so the new material would "interlock" with it), that was not properly done.  Also, the positioning of the complete bridge in the assembly yard and during transfer to it's final location placed tension stress on the last diagonal, which would tend to open the joint and decrease it's strength in transferring stresses.  (this is the "cold joint" issue you questioned - cured concrete is "cold", casting the structure as one piece would have been "hot").  The bridge was thus far weaker than it should have been when placed on it's piers.


 * Lastly, the engineering crew on the ground were apparently completely ignorant of bridge design. Amazingly they failed to recognize that diagonal #11 was in compression, and that it was showing signs of being unable to transfer it's compressive load to the bridge deck.  As a consequence of this failure of basic engineering, they decided to tighten the tensioning rods, thus adding more compressive load to a failing joint.  Which then, of course, failed completely.


 * Someone with more time than me is welcome to look up appropriate citations (much of it is in the NTSB report) and work the above into the article. — Preceding unsigned comment added by 174.48.95.185 (talk) 17:59, 19 January 2023 (UTC)