New Miami Foot Bridge Collapse Bad Engineering?

[Quarlo Klobrigney]

https://youtu.be/2YPl_F06iHA?t=7877 Fox 10 Phoenix

[floobydust]

My condolences to the families and loved ones of the dead, in this tragedy.

The pedestrian bridge was not finished, it is a cable-suspension bridge without the suspension support installed.
It's early but I question the span design could ever support its own weight. There was a crew working at the end that broke.

It was supposed to showboat "Accelerated Bridge Construction methods".

It seems like a fat, obese bridge at 950 tons, for this collapsed section.

[Kjelt]

My sympathies for those involved.
Here in Holland last year a brand new carparking collapsed.
The experts couldn't believe what they found, some concrete plate building technique already in use for decades and in the building community accepted as proven was the cause.
Now every building using this technique has to be investigated and perhaps toredown.
It shows that design errors can be hard to surface.

[Cerebus]

It was supposed to showboat "Accelerated Bridge Construction methods".

That's not a good thing to hear. There was a movement to use "Accelerated Construction" methods for high rise dwellings in the UK in the 60s and it lead to this:

The Ronan point Disaster

[Quarlo Klobrigney]

I can only speculate that the top section weight, without the proper end support, cracked the small vertical(s) and fell to the lower part.
I wish that they would remove some of the sections, not just walk around.

[Quarlo Klobrigney]

The Ronan point Disaster

And then there's the Grenfell Tower..Someone's bright idea of flammable cladding.
This is not just a mistake made by one but by committee.

[raptor1956]

Too soon to say for sure, but it should be pointed out that bridge was set in place just this past Saturday and they were still working on it.  Roughly speaking, there's about four areas of interest:  the design, the materials, the construction, and the environment.  They will look into everything, they have to, but I'd bet the design was OK and the weather wasn't an issue leaving material and construction as the two most likely.  I doubt the materials are the issue, though this is an area that contractors have frequently cut corners on -- they had no live load on it at all so it would have had to have been really poorly designed and/or really cut enormous corners for it to fail from a materials problem without any live load on it.  Finally, the fact that they were still working on it is key and I'd bet that is what will be the outcome. 


Brian

[Stray Electron]

   The local Miami news said today that the bridge was undergoing some kind of stress test when it collapsed.   

[floobydust]

"If workers were adjusting cables once the bridge was in place, the cables should not have connected to the bridge’s structural integrity, Verrastro said. “Once you’re done tensioning those cables, you’re done,” he said.
It’s possible the cables were over-tightened, causing the bridge to elevate slightly in what’s called a camber. Adjusting the cables to address camber would be appropriate, but that would not impact the structural strength.
“If they were adjusting the structural cables, it was to try to put more or less camber,” he said.

Still, adjusting the camber — called tuning the bridge — can be tricky. Robert Bea, a University of California Berkeley engineer and catastrophic risk expert, has studied hundreds of structural failings including the BP Deepwater Horizon. According to Bea, when workers adjusted the camber on a bridge in Australia in the 1970s, it also collapsed. {West gate bridge} “The steel buckled while they were attempting to tune this camber, so it’s very plausible,” he said.
...
The bridge’s superstructure was something Verrastro said he’s not seen in 42 years of designing bridges. Rather than using steel trusses, it employed heavier concrete trusses. The bridge also had a concrete roof, adding even more weight. “This was a very long span and then they used very heavy material,” he said. “The majority of pedestrian bridges are steel.” Steel bridges are about one-tenth the weight of concrete, he said.

copy pasta from http://www.miamiherald.com/news/local/community/miami-dade/article205422719.html

[ez24]

"If workers were adjusting cables

Human error

[jonovid]

if it feels right? when engineers get it wrong
is this a warning to all engineering school graduates?

[DG41WV]

Bit of a different point of view by AvE.

[floobydust]

First fail: "Advanced Bridge Construction" - leaving out the support tower and cables  so you can install the bridge span.
You couldn't swing the span into position with a tower in the way. With no support cables, it's under a lot of stress to support its deadweight.

Second fail: It has absolutely minimal steel, it's all concrete. Massive cheap bloated design is unable to support it's deadweight. 950 tons to support pedestrians?

Third fail: "Stress test" while traffic is flowing underneath. Video of the collapse show the work crew broke (a cable?) before it fell.

Fourth fail: Engineering design review
 "...FIU picked a firm that was not pre-qualified to check the design of the bridge, which was required because it was such a long pedestrian bridge and other unique characteristics. The firm selected, Louis Berger, was not FDOT pre-qualified for this service, which is required under FIU’s agreement with the state. FIU’s design build team is responsible for selecting a pre-qualified firm and ensuring this process is followed,” the governor said in a statement. "

[lordvader88]

Not the type of thing most people would be cautious of. Likewise I 'assume' my roof is not going to fall in on my head.

[tooki]

FYI, AvE has posted a second video explaining what he and the Hive Mind believe to be the smoking gun.

[llkiwi2006]

FYI, AvE has posted a second video explaining what he and the Hive Mind believe to be the smoking gun.

Link here for convenience: https://youtu.be/KtiTm2dKLgU

[jmelson]

   The local Miami news said today that the bridge was undergoing some kind of stress test when it collapsed.   

Our paper said the tension on "the cables" had slipped, and they were being retensioned when the collapse happened.  From the photos, this looks a lot like post-stress construction, where they put steel cables in with the rebar before pouring the concrete in.  About 2 weeks later, they use a hydraulic gadget to tension the cables and then lock them into big steel plates with conical grippers.  Then they cut the end of the cables off.  Once the cables are cut, I don't think they can be retensioned.  But, maybe there is new technology.  Anyway, where I've seen this done (parking garage at my work) they tension the cables BEFORE removing the support and concrete forms.

And, it was reported the engineering firm saw cracks in the concrete a day before the collapse and reported it to the highway department, but nobody heard his message until after.

And, although I'm not a structural engineer, or anything like it, it SEEMS to me that adjusting the tensioning cables while traffic is driving below the bridge is the HEIGHT of insanity.  There are so MANY opportunities for something to go wrong, and it the cable tension is lost, the bridge WILL collapse.

Jon

[amyk]

I can't help but think of this thread also happens to be close by... https://www.eevblog.com/forum/chat/feminist-professor-thinks-'rigor'-is-evil/

[tooki]

I can't help but think of this thread also happens to be close by... https://www.eevblog.com/forum/chat/feminist-professor-thinks-'rigor'-is-evil/

Everybody knows structural engineering is a social construct!

[Marco]

Presumably the bridge was just a truss, with the stays purely cosmetic. Making the web out of tensioned concrete seems a bit cutting edge though. If you have to hold up the hydraulic jack with a crane to tension the tendons I can't help but feel it's all a bit experimental, not suited for doing with traffic.

Making the web out of steel and the top/bottom out of tensioned concrete would be the easy way out. No need to tension all those awkwardly angled tendons with lots of setup time. The top/bottom also have far more tendons sharing load than the web, so if one breaks the bridge might not immediately self destruct.

[chris_leyson]

I got the impression it was just a truss but made to look like a suspension bridge. Having to post stress all the concrete members after the bridge has been partially erected, I don't know, it just seems crazy. Wish I had kept some my old structural engineering text books but I dropped out of civils in the 80s when the recession hit, I don't think they would have been a lot of use anyway certainly not in this case. Prefabricating bridge sections off site and just dropping them in place is nothing new. Just have to wait for the final report.

[raptor1956]

Boy, I gotta say, if the whole cable-stay look was just for show then the entire concept gives me reason to worry about the thinking that went on to design and build this bridge.  I think the analysis the AvE has so far done, though far from conclusive, does seem to point to the work on the post tensioning.  In my first post on this I suspected workmanship and the evidence seems to confirm that.  Six dead for a show horse!


Brian

[BrianHG]

A cloud of smoke shoots out from under the bridge in front of the crane on the left at around 6 seconds in, then, half a second later, it collapses breaking just to the right of that smoke.

[Quarlo Klobrigney]

    ^^^^^^^^^
I've yet to find a clear video of the live "event". All I get is the one with people in front of a screen or very low res. Do you have a valid clear link to one?

[orin]

More discussion from (it seems) people who know about the equipment in use:

http://www.eng-tips.com/viewthread.cfm?qid=436595

And same thread continued:

http://www.eng-tips.com/viewthread.cfm?qid=436699

http://www.eng-tips.com/viewthread.cfm?qid=436802

http://www.eng-tips.com/viewthread.cfm?qid=436924

http://www.eng-tips.com/viewthread.cfm?qid=437029

https://www.eng-tips.com/viewthread.cfm?qid=438451

https://www.eng-tips.com/viewthread.cfm?qid=438966

https://www.eng-tips.com/viewthread.cfm?qid=438966

Edit: Added followup threads.

[Quarlo Klobrigney]

And this.....

[floobydust]

It's an engineering failure- CivE napkin calcs and discussions about the design are brow raising. Mass incompetence in many areas surrounding the build as well.

Why does engineering fail?

We want it cheap as possible. Don't use steel, use concrete as a "truss".
We want it artsy as possible. The bridge should be all unicorns and roses. Fake cable-stays and tower please.
We want it designed as fast as possible. Hurry, get the drawings out asap so everyone else has plenty of time for marketing, costing, and to procure and build and install.
We want it as convenient as possible. Don't block traffic for any reason.
We want it "inclusive". Add students and an under-qualified team to do kindergarten math.

I could go on, but my point is it's very difficult to do decent engineering in the first place.

Corporate pressure on engineers is winning, over safety and ethics.

[Cerebus]

We want it cheap as possible. Don't use steel, use concrete as a "truss".

Don't knock concrete, the Pantheon in Rome was built of concrete in 125AD, is still standing and the dome is still the largest unreinforced, unsupported concrete dome in the world at 43 metres diameter. Nothing wrong with concrete if you know what you're going.

[Bud]

NOTE: This message has been deleted by the forum moderator Simon for being against the forum rules and/or at the discretion of the moderator as being in the best interests of the forum community and the nature of the thread.
If you believe this to be in error, please contact the moderator involved.
An optional additional explanation is:

[floobydust]

Concrete is roughly 1/2 the cost of steel and 1/10 the strength. It's fine in some applications, but here in this truss, concrete can't take tension or shear after a crack.

If they spent $100,000 more on steel I don't think it would've collapsed so I'm saying this is too cheap CivE's.
950-ton span to support pedestrians, seem a little heavy, on the concrete?

“Why they had to build this monstrosity in the first place to get children across the street?” said an anguished Joe Smitha, whose niece, Alexa Duran, was crushed in Thursday’s collapse at Florida International University. “Then they decided to stress test this bridge while traffic was running underneath it?”

[coppice]

We want it cheap as possible. Don't use steel, use concrete as a "truss".

Don't knock concrete, the Pantheon in Rome was built of concrete in 125AD, is still standing and the dome is still the largest unreinforced, unsupported concrete dome in the world at 43 metres diameter. Nothing wrong with concrete if you know what you're going.

He didn't knock concrete. The Pantheon has no trusses, because you can't make one from any known form of concrete. Their tensile strength is very poor. The Pantheon was designed to keep all the concrete in compression at all times, including during its assembly.

[Cerebus]

We want it cheap as possible. Don't use steel, use concrete as a "truss".

Don't knock concrete, the Pantheon in Rome was built of concrete in 125AD, is still standing and the dome is still the largest unreinforced, unsupported concrete dome in the world at 43 metres diameter. Nothing wrong with concrete if you know what you're going.

He didn't knock concrete. The Pantheon has no trusses, because you can't make one from any known form of concrete. Their tensile strength is very poor. The Pantheon was designed to keep all the concrete in compression at all times, including during its assembly.

Did you really think I didn't know all of those "facts"? The Pantheon has no trusses, not because they are purportedly impossible to make "from any known form of concrete" (one takes it that you don't believe pre-stressed concrete counts as "a known form of concrete"), but because it was designed as a dome.

BTW, the Romans actually did make use of reinforced concrete, copying from the Greeks before them who made tension members like lintels out of stone by pouring lead reinforcement into channels carved in the stone. Yup, pouring molten lead into stone to make reinforcements.

Perchance my comment was related to the "steel good, concrete bad" implication. There's nowt wrong with concrete, used properly, including in tension as long as you apply appropriate reinforcement or compressive pre-stressing. The issue here isn't the basic material choice or a choice of 'cheap' materials, on the best evidence available so far it's a either a design flaw or poor construction practices related to the way the concrete was post-stressed as, or after, it was moved onto site.

[Gyro]

Iirc, I think they found than the Pantheon has lots of volcanic pumice in the mix too which takes the weight right down.

P.S. I have a vague memory from the documentary that there was some evidence that the original (higher density) attempt had actually (partially?) collapsed, the pumice filled one being the second attempt.

[donotdespisethesnake]

Iirc, I think they found than the Pantheon has lots of volcanic pumice in the mix too which takes the weight right down.

P.S. I have a vague memory from the documentary that there was some evidence that the original (higher density) attempt had actually (partially?) collapsed, the pumice filled one being the second attempt.

I wouldn't be surprised if they built the same way later cathedrals were built. Keep building until it collapsed. Rebuild with more strengthening until it didn't fall down.

In many ways, we still do the same thing. Until we reach a time were *every* factor can be perfectly simulated in a computer, then some trial and error will occur. That applies to space shuttles and bridges. There is always a desire to make things cheaper, faster, better so there will always be failures.

Prof Henry Petroski wrote the book on engineering failures To Engineer Is Human: The Role of Failure in Successful Design

With the self-confidence gained from their initial triumphs, engineers designed bridges that were structurally lighter and more economical. Of course, this meant that they were also more likely to fail — and they did.

When a bridge failed, engineers received a wake-up call and answered it. The bridge type that failed was often abandoned outright and safer alternative designs were adopted. This naturally led to a period of successful bridges, which once again lulled engineers proud of their achievements into complacency — until a new kind of failure occurred.

This cyclic behavior has continued for a century and a half, with a significant bridge failure occurring about every 30 years.

At least this bridge collapsed now, not when it was filled with pedestrians crossing the bridge. No consolation for those killed already.

[coppice]

Iirc, I think they found than the Pantheon has lots of volcanic pumice in the mix too which takes the weight right down.

The volcanic ash doesn't just reduce weight. It greatly reduces cracking, and makes the structure of the concrete much more stable over the long term. Whenever you see concrete from the ancient world that is still serviceable it seems to be of this volcanic ash loaded type.

[floobydust]

Dashcam video with partial photogrametric reconstruction of the bridge collapse.
Still a lot of speculation on what bit failed; a member, anchor blister, PT tendon, canopy etc.

Over budget and behing schedule:
"... the project was already running about $2.6 million over its $9.4 million initial budget, cost-tracking documents from February show. Originally scheduled to be completed in July, the finish date had been pushed back to January 2019."

Late design changes:
the bridge has to be 11ft longer, to accommodate a future extra lane of traffic. So the pylon was moved, at the end that failed.

[Tomorokoshi]

It reminds me a bit of this disaster:
https://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse

[TerraHertz]

Two interesting commentaries.

Seems they were tightening the tensioning rod in the end diagonal, when it failed.
But, there were two tensioning rods in that strut, with only one being accessible from the top. The other one's adjuster was underneath the span. Did they try to put all the tension on one of the rods, because no one wanted to do the one underneath?

Also finally I understand why the struts are at all those funny angles. To line up with the future 'suspension bridge' structure. (Shown in 2nd video.). But that is virtually a fake visual frill, with no actual suspension cables.
Hmmm... how karmic. The bridge refused to be a fake. Or one could observe that it was designed by people who think fakery is a good idea.


They seemed to think the tensioning operation was risky - hence the crane for the worker's safety harness. (Which he for some reason took off, and so fell with the bridge.) But they didn't stop the traffic... I just... why?

[floobydust]

Even if the roadway was closed for this operation, the work crew would have been killed or injured. Nobody planned on a bridge collapse.

The crew had tightened the PT tendons at the south-end and was then doing the same on the north-end.

It looks like the PT tendon broke free while tension was being adjusted. One of two PT tendons in member #11.
In post-collapse pictures, the blue hydraulic jack A shot out but the second tendon B did not.

Member #11 was highly stressed already and changing tension caused a failure, still exactly unknown, but it looks like the member's lower end or (11-12) attachment point failed.
Still a lot of speculation, the structure was basically weak and adjusting the PT tendons was just was the proverbial straw that broke the camel's back.

CivE's are saying it's a terrible design. Trying to take a huge leap forward in bridge technology.

[raptor1956]

If it turns out the cable stay portion was, as has been reported, just for show I would have serious concerns for the design.  It looks like the collapse was proceeded by re-tensioning the rods, however, the whole design approach gives me concern about what the priority was and it looks like safety was not the design goal at the top of the priorities.  If you're going to go to the trouble of designing and building a bridge with a cable stay structure why not make the cable stay portion handle some of the loads.  This just looks like the University was looking to make an aesthetic statement and to hell with safety...


Brian

[glarsson]

If you're going to go to the trouble of designing and building a bridge with a cable stay structure why not make the cable stay portion handle some of the loads.  This just looks like the University was looking to make an aesthetic statement and to hell with safety...

They can't build a cable stay bride using the ABC (Accelerated Bridge Construction) method. The bridge span must be built offsite and moved in place in one piece. Therefore it can't rely on cables and pylons. The clearly had "low impact on traffic" as a higher priority than safety.

Big, heavy and ugly bridge. Why?

[ez24]

There is a lot of talk about failure during tension.  But in one of the videos, he says because of work changes the member had to be tensioned more to move it then released after because of the cantilever.  But all talk is that it was tensioned again.  So my question is - to release tension, is a hydraulic ram used?    I wonder now if the mistake was that it was supposed to be released but the worker got it wrong and increased it by error?  I haven't heard - did the worker get killed?

thanks

[floobydust]

When they moved the span, supported underneath mid-span by the transporter; compared to in-place, supported at each end- the forces on the deck and end trusses changed from tension->compression;

So the tendons had to be adjusted. I think to back off the nut you use the jack to stretch it first. That might have added stress which caused the failure.

There were strain-gages monitoring while the bridge was moved and installed. Hopefully the two wires were not flipped. It's too bad they didn't leave the sensors in afterwards. They'd notice the forces, if they were different than the design engineer expected.

One guy got killed in the crew, two others hospitalized. Their safety lines seem to have gotten snagged by the falling canopy.

[ez24]

So the tendons had to be adjusted. I think to back off the nut you use the jack to stretch it first. That might have added stress which caused the failure.

This makes sense - thanks

[donotdespisethesnake]

The safety harness was to stop the worker falling off the bridge, not because they expected the bridge to fail.

What is not explained so far is the relation of the cracking to the tensioning being performed when it failed. Those beams were already under compression, so maybe they though adding a little tension would not hurt. But if the cracking was an early sign of shear stress, then adding any tension may have made it fail completely.

It sounds like an off-the-cuff quick fix response to the cracking, without understanding the underlying causes.

To me the angle of the truss members was compromised by the aesthetic consideration and were the wrong angle. Instead of transmitting weight of the bridge down to the pier, it tends to rotate the strut around the joint, creating a lot of shear force.

The lessons for concrete trusses might be learned, but new mistakes will made all over again when the next "new design" becomes vogue. I've come to the conclusion that disasters like this are not preventable, unless people stop doing new things, which isn't going to happen. Human life is the price we pay for progress.

[amyk]

Over a year later comes the preliminary investigation report: https://www.ntsb.gov/news/events/Documents/2019-HWY18MH009-BMG-abstract.pdf

[Quarlo Klobrigney]

Over the next 19 days, the cracks grew until the bridge collapsed. The construction and
inspection firms working on the bridge were aware of the cracks and reported the cracks
to the design firm, asking for guidance. The engineer of record at the design firm
repeatedly indicated that the cracks were of no safety concern. Yeah....

[coppice]

Over a year later comes the preliminary investigation report: https://www.ntsb.gov/news/events/Documents/2019-HWY18MH009-BMG-abstract.pdf

They are pretty damning about both the incompetence and indifference of the engineers, which fits with what we heard before. However, the statement "The  emergency  response  by  local  fire  departments  and  law  enforcement  personnel  was  timely and adequate" seems like rather faint praise. I'd hate to be called adequate.

[magic]

I presume these days there are only two grades:

adequate - according to procedure, can't sue
inadequate - violating procedures, can sue

I would rather be adequate out of these two

[rstofer]

In the reconstruction of the San Francisco Bay Bridge there were also problems with the tensioning rods.  Initial inspection found fully 1/3 of the rods had failed from hydrogen embrittlement.  Later on, another 400 rods were found to have failed from environmental corrosion.

http://www.materialsperformance.com/articles/material-selection-design/2015/11/failed-anchor-rods-on-the-san-francisco-oakland-bay-bridge-a-corrosion-discussion

The previous span fell during the 1989 earthquake and it took nearly 20 years to build the replacement and I sure wouldn't want to drive the new one in the next earthquake.

[orion242]

Ouch.

Lawyers, ready, set, go!

Hate to be that engineer or the one that did the independent review.

[TerraHertz]

Wow. What a cluster f*ck.
Not one party involved in the design, review and construction did their job competently.

One thing missing from the report recommendations is a final paragraph: "The following people should be arrested and charged with manslaughter... "   I guess that would be too simple, and the lawyers wouldn't have as much billing fun.


I'm amazed that a structure with zero load-bearing redundancy was even proposed, let alone approved and built. With design errors that guaranteed failure. Then the highly visible progression towards failure sent everyone into denial, no road closure etc.

Personally I think this is all very consistent with the philosophical insanity of designing a bridge with literally fake 'suspension stays' that were actually just visual adornments to be added after the bridge was in place.

Also maybe unrelated according to some, but my final comment is - Liberalism, it's a mental disorder.

[orion242]

Donno about everyone in denial.

Seems everyone was well aware of the cracking and it was documented.  The construction team raised it and was told its a non-issue.

Sound to me like an arrogant / ignorant engineer getting annoyed and snapping back everything is OK, I did the design dammit!  Concrete cracks, everyone knows that!

Granted the construction team could have halted things, though they are going to rely on the guy with PE after their name for assurance things are safe or any modifications required to be so.

[coppice]

Personally I think this is all very consistent with the philosophical insanity of designing a bridge with literally fake 'suspension stays' that were actually just visual adornments to be added after the bridge was in place.

There is nothing inherently wrong with visual adornments. If they are genuinely adornments, they are harmless by definition. There are some fun ones around the world, which the world would be a sadder place without. For example, in St Paul's Cathedral in London, Sir Christopher Wren designed the roof and dome to be self supporting. Others insisted the dome needed a ring of supporting columns. He built it self supporting, but with a ring of columns just slightly too short to support anything. 

[Marco]

Ignoring everything else, I still think the concept of actively supporting a hydraulic jack with a crane for tensioning is batshit insane

[floobydust]

... Also maybe unrelated according to some, but my final comment is - Liberalism, it's a mental disorder.

It's just insane- the hype and buildup around a simple pedestrian bridge marketed as being a deity - magically attract students to FIU, be an engineering legend in bridge technology, and have unicorns and rainbows, SJW properties - save us from global warming and pollution.

This is some new mental illness, also seen with solar roadways, Theranos etc. - where the hard reality is ignored, all the while non-technical people fantasize about the greatness.

The massive cracking after installation spoke volumes but nobody was willing to hit the brakes, especially the lead engineer.  They are still looking at laying criminal charges. All five parties involved were faulted for not reacting properly to the bridge cracking. I have seen many doomed big projects roll like a freight train, as everyone goes along with it.

[Marco]

I think the company was probably more excited about being able to shave a couple of percent off material costs for construction compared to concrete slab steel web truss bridges, so they could get more design wins, than social justice.

[tooki]

Also maybe unrelated according to some, but my final comment is - Liberalism, it's a mental disorder.

Do you mean the US meaning of "liberal" (left-leaning, pro-regulation, socially progressive.), or the Euro, etc. meaning (laissez-faire economics, minimal regulation, more right-leaning)?

(It's kinda insane how the word "liberal" has come to mean just about the polar opposite, depending on where you are...)

[floobydust]

From the 173 page proposal:

"Bridges designed by FIGG are purposeful works of art, functional sculptures within the landscape, that are created through a careful analysis of the site, contextual and environmental sensitivity, and a regional approach that encompasses a community’s particular needs, as well as the realities of funding and maintenance."

"This design approach is inspired by the values and vision of FIU and this theme. Archetypal design principles of blending shapes, creating shadows, selecting textures, choosing pleasing colors, opening new vistas, using native materials, creating feature lighting and incorporating landscaping were combined to create a bridge that celebrates and is inspired by FIU. Design and construction inspiration came from FIU’s innovative research and technology, educational excellence, and commitment to sustainability.

The project had a "Visual Quality Designer and Sustainability Manager" 

[Quarlo Klobrigney]

Just a bunch of Commie-Pinko words that added up to disaster and death.
Colonel Sam Flagg agrees. Don't look for him to ask his opinion though, because he is invisible and was never there.

[magic]

Do you mean the US meaning or the Euro?

If there is a difference I haven't seen it

The project had a "Visual Quality Designer and Sustainability Manager" 

Not even sure if you are joking.
But I know some building engineers who absolutely detest modern architects.
Not only have they little regard for practicality ("we just design, engineering will figure out how to build it") but they even consider it a badge of honor to be clueless about technical matters.

[tooki]

Do you mean the US meaning or the Euro?

If there is a difference I haven't seen it

I summarized it in my comment. The two meanings are literally polar opposites, so it kinda matters.

[floobydust]

Not even sure if you are joking.

Sustainability Manager on a bridge design having no redundancy? I didn't know if I should laugh or cry.

[rsjsouza]

The project had a "Visual Quality Designer and Sustainability Manager" 

You really can't make that stuff up! Seeing how the electronics industry is affected by a subpar material (lead free) due to environmental impact, I wonder how much that was a factor on this project.

And that is coming from someone that was born in a city where several buildings were designed by one of Le Corbusier's pupils (Oscar Niemeyer) where form absolutely predominated over function - they are extremely impractical and with very high maintenance costs. But at that time these projects had unlimited funds (government) and materials were chosen by their fit, not by their pollutant/toxic/environmental impact.

[coppice]

The NTSB put a 6 minute video describing this bridge incident on YouTube
.
They also put a 3 hour 18 minute video of the hearings on YouTube

[orion242]

The project had a "Visual Quality Designer and Sustainability Manager" 

You really can't make that stuff up! Seeing how the electronics industry is affected by a subpar material (lead free) due to environmental impact, I wonder how much that was a factor on this project.

And that is coming from someone that was born in a city where several buildings were designed by one of Le Corbusier's pupils (Oscar Niemeyer) where form absolutely predominated over function - they are extremely impractical and with very high maintenance costs. But at that time these projects had unlimited funds (government) and materials were chosen by their fit, not by their pollutant/toxic/environmental impact.

The PE of record failing to dig in faced with that cracking, seems either clueless or in denial.  That should have been an hmmm moment they quietly go back to the bat cave and recheck everything.

All those pictures documenting the cracks, and they are not minor yet somehow they thought things where ok?  That member was crumbling in front of them.

[coppice]

All those pictures documenting the cracks, and they are not minor yet somehow they thought things where ok?  That member was crumbling in front of them.

Reports say the cracks were visibly growing day by day, yet on the day of the collapse the designers were still suggesting grouting up the cracks and carrying on.

[orion242]

suggesting grouting up the cracks and carrying on.

Arrogant ahole IMO and a construction team that should have known better but lapped up PE of record ahole decision in spite of common sense to meet deadlines I assume.

[Quarlo Klobrigney]

Quote from: coppice on Today at 12:17:45

Reports say the cracks were visibly growing day by day, yet on the day of the collapse the designers were still suggesting grouting up the cracks and carrying on.

[thm_w]

Not even sure if you are joking.
But I know some building engineers who absolutely detest modern architects.
Not only have they little regard for practicality ("we just design, engineering will figure out how to build it") but they even consider it a badge of honor to be clueless about technical matters.

Then you go back to them and say its not possible to make this design in a safe manner for the costs given.
100% blame here is on whoever signed off and built this as they were responsible for ensuring it met the safety criteria. As they are legally required to have technical knowledge.

Would you shit on the artistic designer of a Disney castle if it collapsed?

[orion242]

designers were still suggesting grouting up the cracks and carrying on

Comical.  Cracking to that degree is a red flag.  Grouting is a cosmetic bandaid, not structural fix for that.  Slow motion train wreck seeing those photos.  All documented no less.  This PE not doubling back faced with this, arrogant ahole IMO.  Guessing attitude adjustment is coming hard and fast.

[floobydust]

The cracks were huge! "40 times as large as the maximum considered acceptable in a reinforced concrete bridge"

“Further contributing to the collapse was the failure of the FIGG engineer of record to identify the significance of the structural cracking observed in this node before the collapse and to obtain an independent peer review of the remedial plan to address the cracking,” the NTSB wrote in its probable cause finding. “Contributing to the severity of the collapse outcome was the failure of [general contractor] MCM; FIGG; [inspectors] Bolton, Perez and Associates Consulting Engineers; FIU; and the Florida Department of Transportation to cease bridge work when the structure cracking reached unacceptable levels and to take appropriate action to close SW 8th Street as necessary to protect public safety.”

Federal prosecutors are deciding if the accident crossed the line into criminal negligence. Apparently that would be a tough case under Florida laws:
"Bureaucrats, contractors, engineers, inspectors all rely on each other’s professional judgments, he [prosecutor Gilbert] said, and under the law, you can’t hold one criminally responsible for another’s failing. “Everything becomes a contest of experts, and that’s always going to be difficult,” Gilbert said. “Just proving they made an error doesn’t mean it was a grossly negligent error.”

https://www.miamiherald.com/news/local/community/miami-dade/article236597488.html

[soldar]

“Just proving they made an error doesn’t mean it was a grossly negligent error.”

Res ipsa loquitur.

[coppice]

“Just proving they made an error doesn’t mean it was a grossly negligent error.”

Res ipsa loquitur.

One error does not imply negligence, but ignoring inputs on multiple occasions, from the paper design stage to the final inspection before the collapse, seems to.

What I find interesting is that nobody wanted to step up and say "shut the road down before people get hurt". Doesn't Florida or US law properly define who is the arbiter of safety in this kind of work? Decades of psychological research shows that if people can assign blame for consequences to someone else, they are prepared to do terrible things. Without clear deliniation of where the buck stops, you really aren't going to get good engineering decisions.

[soldar]

“Just proving they made an error doesn’t mean it was a grossly negligent error.”

Res ipsa loquitur.

One error does not imply negligence,

I disagree. Building bridges like that is something that can be done routinely with no risk of it collapsing. The fact that it did collapse is enough to put the responsibility on the designers/builders without need to prove negligence because the negligence was built into the bridge. It is up to the individuals concerned to prove they are NOT responsible. What happened speaks for itself.

What I find interesting is that nobody wanted to step up and say "shut the road down before people get hurt". Doesn't Florida or US law properly define who is the arbiter of safety in this kind of work? Decades of psychological research shows that if people can assign blame for consequences to someone else, they are prepared to do terrible things. Without clear deliniation of where the buck stops, you really aren't going to get good engineering decisions.

The phenomenon where subordinates will not question the obviously bad decisions of their superiors is well-known and has been studied.

https://en.wikipedia.org/wiki/Crew_resource_management

Cockpit voice recordings of various air disasters tragically reveal first officers and flight engineers attempting to bring critical information to the captain's attention in an indirect and ineffective way. By the time the captain understood what was being said, it was too late to avert the disaster. A CRM expert named Todd Bishop developed a five-step assertive statement process that encompasses inquiry and advocacy steps:[13]

    Opening or attention getter - Address the individual: "Hey Chief," or "Captain Smith," or "Bob," or whatever name or title will get the person's attention.
    State your concern - Express your analysis of the situation in a direct manner while owning your emotions about it. "I'm concerned that we may not have enough fuel to fly around this storm system," or "I'm worried that the roof might collapse."
    State the problem as you see it - "We're showing only 40 minutes of fuel left," or "This building has a lightweight steel truss roof, and we may have fire extension into the roof structure."
    State a solution - "Let's divert to another airport and refuel," or "I think we should pull some tiles and take a look with the thermal imaging camera before we commit crews inside."
    Obtain agreement (or buy-in) - "Does that sound good to you, Captain?"

These are often difficult skills to master, as they may require significant changes in personal habits, interpersonal dynamics, and organizational culture.

[coppice]

“Just proving they made an error doesn’t mean it was a grossly negligent error.”

Res ipsa loquitur.

One error does not imply negligence,

I disagree. Building bridges like that is something that can be done routinely with no risk of it collapsing. The fact that it did collapse is enough to put the responsibility on the designers/builders without need to prove negligence because the negligence was built into the bridge. It is up to the individuals concerned to prove they are NOT responsible. What happened speaks for itself.

Errors are always made. That is normal in engineering. The difference between bad engineers and good engineers is not that the good engineers make no errors. Its that the good engineers make fewer errors, and are endlessly skeptical about whether they have got things right, leading them to use every form of checking they can think of. There appear to have been several points at which relevant checks highlighted the problem, but no action was taken. The consultants who were contracted to verify the design were only asked to verify the completed design in place, missing out any evaluation of the stresses that might occur during the assembly process. So, the verification process was not taken seriously. This is negligent behaviour.

[tom66]

Liberalism, it's a mental disorder.

Yes, unregulated capitalism is sure a disaster. That's what you mean by liberalism, right?

[soldar]

Oh come on! We do not need to make every thread into a political issue. This is about the collapse of the Miami bridge. Capitalism and socialism have as much bearing on the issue as the conjunction of Uranus with Mars. Please.