The Disaster That Changed Engineering: The Hyatt Regency Collapse

[@TomScottGo]

It can be tricky to make a video about disaster, but I think Grady's done a really good job here. I didn't work out what the problem with the design change was until he explained it. Go check out his channel!

[@Mtron1000]

Hold on, how come this video is shown as being posted only 20ish minutes ago, but your comment above is 2 weeks old?

[@BavoLuysterborg]

Tom must have uploaded all guest videos before his time off. They're only visible to him at that point, but he can still comment and pin comments while it's not published publicly.

[@BoterBug]

Video was scheduled ahead of time, comment added before the publish date. Tom does this with every video :)

[@jej3451]

Apparently you can comment on one of your own videos before you make it public.

[@Zestyclose-Big3127]

Why do people seem to ask this every video?

[@PracticalEngineeringChannel]

Thanks Tom for having me on your channel! I hope my shirt was red enough to satisfy everyone here!

[@TomScottGo]

+Practical Engineering I've learned that I can't wear a shirt any redder than yours. I look like a crap magician.

[@moritzkockritz5710]

Practical Engineering not perfect, but it'll have to do.

[@PaulTomblin]

I read the report on the disaster and they said that the original design (with a single hangar) was NOT compliant with the building code.

[@case_sensitive]

2 weeks ago?

[@ElectraFlarefire]

I missed the 'what did this disaster change' bit. Re-watched the video and still didn't see it. Did I miss something?

[@HonestLeigh]

The "friend on a rope" analogy is excellent. I didn't quite understand the magnitude of the issue until that.

[@armorsmith43]

Leigh Dupuy There’s a lesson: when you want to make a technical analogy, try seeing if you can replace any of the components with humans. It works particularly well for explaining software.

[@BillySnowball]

I found it misleading, as it focused on the nuts and rods. As was briefly mentioned the failure mechanism was pull-through/splitting failure of the nut/beam due to the beams not having thick enough walls. Although the nut on the lower face of the upper deck was having to carry the load from the lower deck if the the tension rod had adequate capacity to carry the loads of both decks it's fair to assume this nut was well below 50% capacity. The failure occurred due to the upper beam being crushed by the upper and lower nut loads acting in opposing directions. This likely caused localised buckling in beam webs, probably causing them to bow outwards. This would have created 'hoop' tension in the beam. Weakened locally by the upper and lower bolt holes the beam did not have adequate tensile area to resist the 'hoop' stress. This is speculation but I can't see another reason for the beam splitting like this. You would normally just expect the lower nut to tear through the lower flange. The fact the beam split in half makes the failure mode quite interesting. Normally this would be caused by a shear load, however the way the beam was loaded, as far as I could tell rules this out. Anyhow that's my best guess with limited info provided

[@kyleapuzzo9819]

@@BillySnowball the beam was actually welded at the top and bottom from 2 separate channels, thus that was the point of failure causing the split

[@dhy5342]

@@BillySnowball you have it right. It wasn't the rods, nuts or washers that failed. It was the opposing forces on the cross beam, exacerbated by the additional holes which weakened it. Also, the box beam was made by welding two U-beams together with the bolt holes then drilled through the welds, which broke because of the weight forces. If the beam had been oriented with the welds on the vertical faces and the holes on the solid faces, it's doubtful that the rods would have torn through, even if the welds broke and the bar collapsed.

[@imaginarystranger1974]

You seriously didn't? That's... stupid. No offence, but that's, like, common sense. Obviously the top person will hold the weight of his friend as well, instead of just his own.

[@derekantrican]

I had to do a 80ish page report on this in college (with calculations down to the weight of every element - including the carpet and lamination on the concrete). The other main failure was the fact that the "box girders" (made of two "C-beams" with the open part facing each other) were originally planned to resemble "I beams" (the two "C-beams" oriented such that their "backs" were against each other). The "box girder" arrangement was significantly weaker than the "I beam" arrangement

[@tomdchi12]

Am I inferring correctly that as built, the lower flanges of the C channels yielded (they were "cantilevered" in this arrangement), and that if they hand been "back to back" the load from the nut+washer would have been in line with the web of the C channels, thus they would have been much stiffer and less prone to yield? The "flanges facing in" arrangement would look more like a "box" and thus cleaner, but was the idea simply to weld the edges of the flanges together, then drill holes through for the rods? Otherwise, I don't see why they would have changed that detail from "back-to-back" with the webs close together - was it "a pain" to space the webs apart for the threaded tie rods?

[@blackoak4978]

Thomas Donalek good questions, I hope he answers u

[@Neceros]

I'd hire ya.

[@derekantrican]

Haha, thanks Neceros! Got my bachelor's in Mechanical Engineering, but I'm working as a Software Developer now (so those days are behind me)

[@Neceros]

It's all good. The more you know the more human you are. I'm a web designer so I understand the switch.

[@enhydralutra]

Having grown up in Kansas City, this disaster wasn't only taught when I started into engineering, but was taught in several of my high school science classes, too. It really shook up the community around here, enough that nobody ever wanted this to happen again.

[@toobusytocreateaname]

Lutra Nereis +

[@tauneutrino1able]

Lutra Nereis my father was a KCFD captain and this was pretty much the only "one" that gave him nightmares.

[@Grapefruit_cosplay]

Lutra Nereis the Hyatt is still in downtown right ? with newly built walkways ? I have been there a few times since learning about this disaster in a structures course and it always seemed eerie to me.

[@tripleforte]

Elizabeth Witsken , one was replaced with ground supports instead of hanging. A third walkway, that didnt fall, was removed. It is no longer operating as a Hyatt.

[@Horkslair]

They call it the Sheraton Crown Center now, but its still there. Crown Center is about half a mile south of the main downtown core of KC MO.

[@typhoon-7]

I was told on day 1 of my engineering degree "if a surgeon makes a mistake, there's a good chance someone could die. If an engineer makes a mistake, there's a good chance many could die"

[@boxinabox6608]

What if a surgeon accidentally released nukes on China?

[@Lenioogami]

How right it is

[@belfast4893]

Only thing is, there will be multiple people double checking an engineer work before final execution. So it would take a group of incompetent people to actually make a critical mistake irl. While a surgeon…he is not gonna have anyone check after his work, the moment he makes a mistake to a patient…it’s over.

[@JayTemple]

I used to teach algebra at a community college. One day we were waiting for our classroom to empty so we could take a test, and a student was feeling nervous. (The exam included complex numbers.) I told him, "There is no stress. If you make a mistake with complex numbers and you're an architect, people might die. If you make a mistake with complex numbers and you're an electrician, YOU might die. The worst that can happen if you make a mistake on a test is that you lose a few points."

[@Alucard-gt1zf]

​@belfast4893 except in this case nobody checked his work now did they?

[@briangarrow448]

I remember this tragedy. I was an apprentice boilermaker working on a nuclear reactor containment vessel. The vessel was built from the ground up, a standard practice in construction. there was a hanging roof system that covered the vessel from inclement weather and was used as a storage area for welding equipment, portable toilets, and modular offices. So everything was on a set of hangers that carried the load to the exterior concrete vessel containment. I am grateful for the engineers from Chicago Bridge and Iron for doing their job properly. The days immediately after that accident I recall a number of my crew spent extra time closely examining our project.

[@samrowe2889]

What local

[@DavidCowie2022]

There's a Dilbert comic in which Dilbert is telling a school class about engineering. He says "If you are successful in your career as an engineer, you will receive a certificate of appreciation in a handsome plastic frame. If you are not successful, people may die. Now, who wants to be an engineer?" [Cue horrified looks on the children's faces].

[@diamondflaw]

Came to comments to look for this. Thanks for already putting it here.

[@macknack123]

who invented 'nuclear energy' without an exit strategy for the waste?

[@macknack123]

who invented plastic and galvanized rubber without a recycle plan?

[@macknack123]

how about why 'cloning' produces Zombies and tasteless food and couch potatoes

[@jameslaidler4259]

David Cowie Hey I like it, honest and blunt. And very true.

[@MsIrrealis]

it is abslutely insane to me, that this happens so infrequently. It is almost a miracle how safe our constructions are in total.

[@jasonreed7522]

Its not insane, our building codes are insanely long and every single line exists for a reason, usually because someone died so that line had to be added. Our constructions are safe today because of the lessons learned everytime a tragedy happened. Our constructions are also unsafe because of constant pressure to finish (hurrying and "haste makes waste") and constant budget concerns resulting in poor maintenance.

[@DimT670]

@@jasonreed7522 don't forget deregulation and desire from provate entities for more and more profit. I don't understand how people can be against a central government and then go inside their homes that don't fall on their heads only thanks to said government

[@codyoftheinternet]

I know of people that died in that accident. My aunt was supposed to be there. It’s a big deal in my family and my dad always thought the proper way to educate me about it was to talk about the fact that even small mistakes can have large consequences.

[@howardbaxter2514]

Look no further than all the failed rocket launches. Sometimes it’s as simple as a faulty bolt or wire.

[@historiclift27]

My great aunt and uncle were almost there at the tea dance but last minute decided not to go. My great uncle lost his law partner in the collapse. I stayed there in 2005 and got to hear stories about it. It was a very eerie experience.

[@dayradebaugh]

Very nice demonstration of how the load on the box beam doubled. We've studied this disaster for 15 years in my Engineering Ethics class at Wichita State. However, I disagree with the claim that this disaster changed anything at all. Design changes, such as the one proposed by Havens Steel, the walkway fabricator, are proposed as a matter of course. The simple reason this was not adequately reviewed was the pressure to complete the project. Such pressure has only grown in the construction industry, leading to more inducements to cut corners. Two weeks ago my students delivered a presentation on the forensics of the Hyatt disaster, and claimed that such an event could not happen now, because we are so much better at predicting loads, and design skills and codes have improved. A week later, the FIU pedestrian bridge collapsed. These disasters will continue to happen for the same reason they have in the past--we're in a hurry.

[@dn1675]

I would disagree; most failures NOW happen to occur because of construction/fabrication error - not design error.

[@IsaacDozier1]

@@dn1675 I agree. Worked as QC at a truss plant and quit because the lack of quality frightened me and the inability for anyone to take it seriously was the tipping point. Truss missing plates on both sides of the joint.. seriously?!

[@GH-oi2jf]

Day Radebaugh - Couldn’t happen again? Florida International University pedestrian bridge. Fortunately, there were no pedestrians, as it was still under construction. Unfortunately, traffic was flowing underneath it.

[@battleskorpionYT]

@@GH-oi2jf you didn't even read his full comment it seems lmao

[@peterkim4568]

@@dn1675 that's exactly what this is, though: a construction/fabrication error. The original design would not have failed in this manner because the nuts supporting the top walkway would not have been doubly-loaded like this. The change to the design was submitted while they were in the thick of building the actual thing and is, at the face of it, a very sensible modification. To have to thread a nut through THAT much threaded rod really is a stupid thing to do, and perhaps the more effective solution would have been to have a female-to-female coupler to mate two sections of threaded rod together. But that would have been a custom part and would have resulted in delays to get a new part designed, added to the drawing(s), run through all the appropriate design reviews and analyses, and then fabricated. @Day Radebaugh is correct. Modern society demands demands demands that things be done faster and more efficiently, and the demand to keep building and making faster and faster will always incentivize people to perhaps let their vigilance slack in the name of not being the long pole. It's not like there's a big book of rules saying "thou shalt submit thy designs to the committee whenever thou increaseth a bolt hole by more than 0.01"". That big book of rules doesn't exist even now, not after the Hyatt regency disaster. People have to make these choices on the fly, often using their instincts, and there will always, ALWAYS be pressure to get it done NOW.

[@william.i.herman]

“Hyatt Regency Collapse” sounds like some sort of apocalyptic quantum physics event that would rip apart the universe.

[@PabloSanchezVideo]

"Hyatt Resonance Cascade"

[@twasb2000]

It was for the 100+ people that were on it. We were taught this case study at university and it has formed part of the many experiences that help you realise the importance of basic engineering control.

[@alanwatts8239]

There would be no one left to name it that way.

[@jamespeake4883]

Sounds more like a political upheaval to me

[@Leandro-vy7nj]

There are not many currently valid apocalyptic quantum physics event theorys, and none of the events stated in them would rip apart the universe, only the matter in it, and only at the speed of light, so they wouldn't reach all of the universe.

[@ilikepepsi3883]

I’m the farthest thing from an engineer but the rope hanging analogy makes it make perfect sense.

[@arduinoversusevil2025]

Hey! I know that guy!

[@mzflighter6905]

Hey! I know this guy too!

[@jeffswetlikoe2469]

Hey I know all these guys!

[@thewelfairshop4164]

Ahh the shopmaster

[@ririgawa1665]

Hey! I know this guy too!

[@DaddyBeanDaddyBean]

AvE's analysis of this incident would include a LOT more profanity.

[@AnnaKin]

Before my degree, I used to go on roller coasters and have fun on them. Then I got a job and met more engineers. I don't do theme parks anymore

[@erniew5805]

once i started working in the oilfield .i looked at the guys running the portable roller coasters at the fair.i looked at all the pins and keepers holding the coaster up never rode any fair ride since.

[@erniew5805]

i looked at a ride after that saw a U clamp on the wrong way on a support cable thought that is why i wouldn't do any ride

[@generalharness8266]

@@erniew5805 I would have thought that would only improve the reason to ride a roller-coaster? I mean the whole point is to terrify you so surly it would have been more effective on people who knew the risk.

[@svis6888]

Wdym? Roller coaster are safe...

[@lemonandgaming6013]

​@@generalharness8266 i thought billions of years of evolution gave us a survival sense but apparently not? like, the point of a rollercoaster is to be a thrilling experience, and thats fun and i like it, but its point isnt to KILL you because of negligence??

[@Croz89]

I believe the way the rods attached to the box girder was also a factor, which was two U beams welded together. It meant that the bolts were attached to the weakest thinnest point in the box, encouraging the weld to unzip and fail. An extruded box or something other than a box may have been strong enough despite the design change.

[@Zizzily]

Yes, the rods went through the welds where the C beams met, so the weight basically tore the bolts and washers through the welds.

[@Iceykitsune]

Remember, the fourth floor box girder was originally intended to take only half the load it ended up taking.

[@KB4QAA]

Icey: The video failed to mention the contractors' change in the box beam fabrication which created a weaker box beam.

[@mrdojob]

Even if they MUST use those shitty channels, the disaster could have been avoided if they got a labourer to make a few 100 by 100mm square washers to go with the nuts. It would have taken just an hour to make them all.

[@csonkaperdido]

A circle is WAY stronger than a box!

[@ehhorvath13]

Can confirm they do indeed still teach this in engineering school! Never underestimate the responsibility you have as an engineer to the well being of the society!

[@petermgruhn]

We teach it in architecture school.

[@Romualdomgn84]

4 minutes video, but how clear it was shown and explained. Example with people, hanging on the rope, gives even more deeper understanding of the situation happened. Thank you Tom and Grady.

[@GedMaybury23]

I have a curious connection to this disaster: I stayed in the Hyatt Regency only a few months after it was finished (around Thanksgiving; 1980). I walked those bridges dozens of times, trying to get my baby daughter to sleep or simply admiring the building. (I'd studied architecture, and have designed a few buildings.) Naturally enough - I was horrified to hear of the disaster a few years later. A total clusterfuck. Now I finally understand the issues. (I thought it went the other way around - that they wanted the hanger-rods to be aligned, not staggered.)

[@howardbaxter2514]

Weird how so many of us have come so close to disaster. I remember driving under the FIU bridge the day before it collapsed.

[@Qoukuun]

German Civil Engineer Here. The Hyatt collapse was a Bonus Question in Statics/Steel structures Exam 9 years ago at my University. Searched videos about it on KZbin and found your Channel. Great Work and very good Videos. Ich salute you.

[@Robbedem]

National Geographic needed almost an hour to explain this... :o (Seconds from Disaster: Skywalk collapse)

[@halimceria]

Robbedem well, Seconds from Disaster is more about dramatisation, story from different views and people. this video just facts of the incident, its explanation and effect to engineers out there.

[@xxwookey]

That's TV science for you. Way too slow to be much use. KZbin is a huge improvement in that regard.

[@BobElHat]

Yeah, but that hour was 15 minutes of adverts, 35 minutes of telling you what happened before the adverts, 2 minutes of into and credits and 8 minutes of actually explaining stuff.

[@Robbedem]

haha, so true. :) What's even worse, about half the adverts are about programs from National Geographic itself, sometimes even an add for the program you are already watching!

[@zeiitgeist]

interviews, the process leading to the cause, the discovery of the fault and lastly the solution, so yes it would be padded out.

[@jmwild1]

I was born and raised in KCMO, and have spent most of my life there since. I was 8 when this happened, and it gave me nightmares. Ever since, I have developed something akin to a phobia of walking under bridges or suspended walkways.

[@kcgunesq]

I was a couple of years older so maybe I see it a bit differently. But I can tell you this - given the choice between the Hyatt and the Westin (at Crown Center), I always choose the Westin. My perception of the Hyatt brand in KC was forever tarnished and even though it is no longer a Hyatt, I would be uneasy staying there.

[@fjb4932]

I most assuredly would walk Under before i walked On them ...

[@DamonWakefield]

The parents of one of my grade school friends were killed in this disaster.

[@domsusefulstuff]

Wow! Great explanation of a deadly problem. The props were excellent and your example summed things up perfectly. I also appreciate the way you used this incident to talk about the trust that we all put in the builders of our world. "Implicit handshake" was such a succinct way of putting this profound issue. The dialogue was exceptional; no more or less than needed (well engineered one might say :-). Great production in general. Subscribed Sir!

[@PracticalEngineeringChannel]

dduncombe Thank you. This is really kind!

[@domsusefulstuff]

I've been watching your videos all day. It's obvious you put a lot of thought into your work and you're a great teacher. Thank you for lots of exceptional content.

[@scottsmith9192]

I’m no engineer, but I seen immediately what the problem would be as soon as you showed the new diagram. What an oversight.

[@TS_Mind_Swept]

It's times like this I'm glad I don't get invited to parties

[@ke7eha]

I stayed at that hotel this past summer. I recognized the lobby from my engineering ethic class. It was surreal, and then I went to the 2nd floor skywalk (rebuilt with enormous support columns) and looked up this disaster to be sure. My folks were almost at that tea dance as well. Small world.

[@ichweinicht1858]

I am civil engineering and was reading about hyatt regency kansas failure, I wanted to learn more and searched it on utube and as soon as I saw the thumbnail of "practical engineering" i clicked on it. I learnt a lot today -subscriber of practical engineering

[@reallyWyrd]

The example with the little beams is the best one I've seen to explain this.

[@Robyrob7771]

It’ll be interesting to see what led to the condo collapse in Miami earlier today. Prayers to those lost and injured in this disaster.

[@jmchez]

Betting on sinkholes and the fact that for forty years nobody noticed the ground shifting. Coincidentally, that building was constructed the same year that the Hyatt disaster happened.

[@jannegrey]

Well - Grady has made a video about this.

[@Sashazur]

I’m here from the future to say that the condo collapse is looking like a combination of bad design, poor quality construction, and deferred maintenance.

[@Olivershoesoff]

In engineering school, we all learn about this, and it took a full period what you did (better) in 4 minutes. Great job!

[@sethprops4404]

I’ve been in KC 14 years, have seen this video before, and just now put it all together that this is right down the road from me. Great stuff.

[@WillN2Go1]

I've stayed in the KC Hyatt twice about twenty years ago. The second time there was a convention of young engineers. None of the young engineers I spoke with knew anything about the disaster. I don't think any of those I spoke to were structural engineers (I think had they been I would avoid all large buildings, bridges, freeways, infrastructure...). I'm not an engineer of any sort and I knew all about it. If you haven't been there it's very unsettling to think 119 people died in this lobby. I'm glad they didn't tear the whole building down, it's a lesson to us all in everything we do.

[@visano.]

No wonder why my structural analysis and design professor was hard(strict) on us. We would write long impositions if couldn't score a certain high mark even though we crossed the pass mark. He said, either you really become good at this or you don't become an structural engineer. Steel design was my hardest subject

[@davidgillies620]

The injuries were so appalling and the casualties so many that it had a profound effect on the rescuers. The collapse was a failure of systems, not just of design. Engineering really does encompass much more than simply fabricating things.

[@brandonjc13]

This gets recommended to me after the condo collapse in Miami. Nice.

[@msr1116]

Same here. At this point, having read an analysis from every amateur out there, including conspiracy theorist clowns, as to what the collapse video would, should or could mean, I'd like an actual seasoned professional structural engineer to weigh in with his or her opinion.

[@extrastuff9463]

@@msr1116 I doubt you'll see many in that category make an actual statement or speculate on it, at least not until a full official investigation report is available. Unless there are obvious glaring faults visible that might've been caught before with for example a bridge showing cracks, rusted essential parts, whatever there's not much to go on externally with a building like that. And even if such information is available speculating on what could be the cause in public isn't a thing I'd expect most certified and experienced engineers to do about a specific incident. Going over various theoretical scenarios of types of neglected maintenance/bad construction and the failure modes of a structure maybe? But I'd expect them to be very careful about not making implications about what happened at that actual collapse in Miami.

[@Nathanatos22]

KZbin’s sense of timing is… interesting

[@shoot991]

YES! Thank you for getting a hold of Practical Engineering love all of the guest hosts!

[@lebagelboy]

Also instead of using solid box sections they used two C channel sections welded together and they put the connecting bolts through the weld. This was another bad idea because it significantly weakened the connection. You can see the result at 3:10 where the two halves of the "box" section split apart. Btw if anyone wants to know more about structures I recommend Levy and Salvadori's "Why Structures Fall Down" it's a great book and chapter 15 covers this disaster in more detail. There's also some other great examples like Ronan point in the UK.

[@guatagel2454]

I saw a documentary 15 years ago and I didn't understood the issue with the bolts, and why the weight doubled on the bolts. Now I understand. Thank you!

[@degrelleholt6314]

It is important to study mistakes and "put the fear of God" into professionals. When I learned to fly, I cannot remember how many films of aviation disasters stemming simply from pilots not doing a pre-flight check I had to watch. I never missed or shortened a pre-flight check and always had a clipboard with a list of things to check off as I went.

[@mujtabanadeem3901]

Have you read the Checklist Manifesto by Atul Gawande?

[@MaxMakerChannel]

Typically standardised nuts are designed to support more force than the screw. So the load on the nut should never be an issue. But in this case the beam around the nut got crushed.

[@AlRoderick]

I remember that walkway as an example in a physics textbook from my AP class in 1998.

[@MaxMakerChannel]

Alexander Roderick We had that example at University numerous times. It comes up whenever you discuss the factor of safety.

[@willnettles2051]

Good presentation. I stayed at the KC Hyatt twice in 2002. I'm not an engineer but I spent a lot of time walking around looking at where the walkways used to be and thinking about it. On my second trip there was a young engineers' association convention. In the elevator I said "I know why you chose this hotel." They had no idea. Most seemed to have never even heard of the collapse. Now maybe there were no structural engineers on that elevator, but I know about it. I agree it's critical that we learn from past errors, even if they are not in our immediate area of training and expertise.

[@RJA10001]

Here in Canada we had a bridge collapse. I won't go into detail about it, but now all Canadian engineers who graduate with an engineering degree are rewarded with an iron ring (originally made from the iron from the bridge that collapsed) to wear on their writing hand. So any time they're working on designs the dragging of the ring on paper reminds them of what they are doing. I don't study engineering, it's just a pastime of mine

[@kilikus822]

In the entirety of Canada?

[@1L6E6VHF]

Very interesting, and a great tribute. Was the bridge you speak of the cantilever Pont du Québec?

[@robertlee5456]

Unfortunately this is a myth. They made it very clear during my Iron Ring ceremony that the rings were not, in the past or present, made from any fallen bridge or other engineer disaster remains. Modern rings are made from regular stainless steel.

[@c31979839]

@@kilikus822yes in the entirety of canada

[@c31979839]

@dolofonos just because you're an engineer, doesn't mean you're not an idiot.

[@WilliamSebren]

Just learned about this tragedy today from a podcast, and had a general understanding from their description. This made it so much easier to understand - thank you!

[@FalingDutchman]

Great video, will sub to Practical Engineering! Although I am a software engineer, I find other engineering area's very interesting :) You cannot know enough!

[@Czeckie]

Knowledge is Power. France is Bacon.

[@Frentzen127]

Plasmaboo whoosh :p

[@GH-oi2jf]

dolofonos - That’s not true. I am a (retired) software engineer with two degrees from engineering schools. We aren’t certified like P.E.s, but I think it is correct to call myself an engineer. I don’t like it that people without engineering degrees can call themselves that, however.

[@FirstNameLastName-gq3uv]

A code monkey with a 10 week coding bootcamp under their belt is NOT an Engineer.

[@FalingDutchman]

@@FirstNameLastName-gq3uv what about almost a decade of experience?

[@5GTower1000Percent]

I have seen this video like 4 or 5 times now. I am not sure if I found his channel thanks to this or if I have known him slightly before hand. Nevertheless I have watched a lot of his videos and like them. It is very similar to Tom Scott, calm, factual, explained for people with no prior knowledge. I was never a linguistic kind of guy, nor was I ever a engendering kind one. But you guys managed to fascinate me for both. It is astonishing how much a good teacher can do. Because I have a spelling and grammatical weaknesses / issues I never thought I would actually become good with words or be interested in languages. I was proven very wrong. I managed to go from a merciful 5 to nearly a 1 in German and also English. My teachers were nice enough to not let me fail all my classes with a 6 which I would have gotten, because I literally had double or tripple the allowed mistakes in exams in these subjects every time. So I was failing for like 3 people in both of them. I hated these subjects. I hated language. I even get to hear from my aunt every few months how I used to complain about "who even needs English?". Now my English is very fluent. I feel confident talking to other people in English. I always hated that language lack logic. For some rules there were more exceptions then cases to which the rule actually applied to. It drove me insane. But it turns out language has a lot more logic in it when you know their history. My latest teacher in German middle school laid the foundation for improving in these two subjects. And you made me really enjoy them. I just realized how much I love coming back to your old videos, especially the language one, or even the guest videos. You and all the people you invite are able to teach difficult topics in such a fantastic way that I am happy to watch them more than once. Thanks to all of you. You too Grady. I very much enjoy your videos as well.

[@andrewjc13]

So glad to see Tom and Grady in one video, you both have amazing channels!

[@Mamaplusone]

As someone from Kansas City, and as a large fan of this channel, I am so happy to see how well-done this video was. Thank you for covering such an important topic.

[@PorcuPineAppleSauce]

We learned about this and watched a video about it in my physics class. We also used the looping water slide at Action Park for part of a lesson

[@jmchez]

They never used engineers to design the rides at Action Park. They just built anything that looked like "fun".

[@whonelly1220]

So happy to see Grady on your channel Tom. Grady makes some great videos and his explanations and demonstrations are wonderful!

[@asgaines]

Grady and Tom, you guys are both kickass!

[@danfishlock8306]

This specific case was shown to us on day one of engineering at U Waterloo in 1992 - only 11 years after it happened. Amazing to see it pop up here about 40 years later!

[@jasperdiscovers]

Tom Scott is so magical, he comments 2 weeks ago.

[@neatbarker]

my great uncle was there when this happened, and I currently live a 20 minute drive from this hotel downtown. I've always been interested in disasters like this and i finally found someone who explained it in an easy to understand fashion. great video!

[@cliffordvuong3116]

now i understand why my statics professor was such a hardass...

[@romarub]

This video makes the problem stand out - clearly and succinctly. Videos such as this are essential in the education of engineers and architects A magnificent piece of work. Congratulations.

[@Cheeky_Chelsea]

They taught me this in my structural engineering course at uni, I won't let this happen in my buildings

[@CalvinHikes]

I remember this being explained to me back when this occurred. And I didn't understand it. Our school teachers kept trying to explain screw threads to us. History repeats itself in that I am being taught this again.

[@koberobinson7647]

Of course this is getting recommended right now

[@steelencounters]

Tragic. Grady did a very good job of demonstrating the problem identified in this disaster.

[@bereisgreat]

really great video, he explained it super well and the rope analogy was spot on

[@ByteMe619]

The animations make this really clear to understand, and the experiment set up was a nice touch too

[@pssurvivor]

Seems pretty obvious, but then hindsight is 20/20.

[@GH-oi2jf]

Pallavi Sanyal - Structural engineers are supposed to have foresight, aided by experience and mathematics.

[@omarkiller2222]

@@Sid483 Engineer's also have foreskin so women can't be engineers.

[@Gweinman]

I'm guessing this showed up in my feed because of the collapsed building in Miami last night.

[@TheElJefe]

I was thinking the same thing.

[@ireneswackyjournals8810]

Yes.

[@CrimsonNorway]

Very well explained, I've seen a documentary and another video about this disaster but never fully understood the subtle difference in the designs. Great video!

[@yendub]

This Saturday is the 40th anniversary of this disaster.

[@everetthorner]

Just watched this video for a second time in my structural engineering class! Still an excellent video.

[@Huntracony]

I was almost correct. I thought the problem was with the top walkway having to carry the load of the bottom walkway and that the walkway itself might break. I didn't realize the bolts would be the problem.

[@qirat73]

the bolt didn't break, basically the ends of the walkways where the bolts were split open and slipped past the bolts, so the bolts were fine and could take the load but the walkway couldn't

[@Huntracony]

qirat73, So I was right. I was just wrong about being wrong. Thanks for validating my already probably too big ego.

[@toobusytocreateaname]

Huntracony +

[@toobusytocreateaname]

Huntracony +

[@toobusytocreateaname]

Huntracony +

[@godly74]

Great guest video! I've researched this disaster for a safety project before but it's interesting to hear it explained so eloquently.

[@rahulsundaresan218]

We learnt about this in physics class. Fun to see it here

[@toobusytocreateaname]

Rahul Sundaresan +

[@klefusmcdonald2644]

The 3 R's.

[@KS1776]

Couldn't stop looking at that crazy wiring going on in the background... But the info is sound and a great reminder on keeping perspective on every aspect of your job each action has a reaction.

[@spinningchurro]

Finally a smart video on trending. This will never happen again.

[@generalharness8266]

It did 3 years down the track.

[@TidyTraxx]

Very weird when one of your favourite KZbin channels appears in one of your other favourite KZbin channels! Thanks to both of you for making awesome videos.

[@Wordsnwood]

Hey Grady! Great to see you over here. Everybody go subscribe!

[@DJToneRI]

I love little short and to the point bits of interesting information like this. Great work boys

[@simon_patterson]

Very interesting, and well explained!

[@PracticalEngineeringChannel]

Simon Patterson Thanks!

[@Hixie101]

I don't leave comments often, but this video is great! I often have to sign off on design changes and videos like these remind me to think about every single possible scenario

[@toobusytocreateaname]

Hixie101 +

[@JohnR31415]

This is a fantastically well explained disaster... And a really bad bit of design change :(

[@_JayRamsey_]

All I needed to finally understand this was that picture of the split box. Makes so much sense now that I know that was the weak point. Thanks!

[@Sashazur]

But it wasn’t just that weak point. Even if that connection had been sturdier it still wouldn’t have been designed to carry double the weight.

[@arooobine]

And that my friends is why you unit test before you deploy.

[@toobusytocreateaname]

Benjamin Hershey +

[@themodernshoe2466]

I've only heard of unit testing for software development. How do you unit test for engineering?

[@misterkite]

Unit testing wouldn't have caught this at all... as it was an integration problem.

[@PracticalEngineeringChannel]

Generally not feasible for civil structures unfortunately

[@iabervon]

Unit tests, integration tests, regression tests, QA, burn-in tests... And then you get the last-minute call asking if you can fix one tiny problem. "Something like this?" you ask, sending them a completely untested patch. Surely they're not going to just apply your patch and deploy without rerunning the tests, or even any code review, right? Right?

[@birdy_coolbeans]

Always great to see my favorite channels collaborating. Thanks Grady!

[@groundsalt2199]

There’s a reason why every engineer in Canada gets a ring made from the metal from the iron workers bridge.

[@petergreenwald9639]

Rather more of a myth. Wedel, Kip A. (2012). The Obligation: A History of the Order of the Engineer. AuthorHouse.

[@peanutismint]

Really interesting explanation. I just happened to be reading about this tragedy about 2 weeks ago so it was interesting to have the failure point visualised so succinctly. Thanks Grady!

[@CharlesTheClumsy]

Oohh, he's the guy that made the "Sand Castle Holds Up A Car!" video.

[@thaerosthedragon1930]

My high school engineering class used this and the tacoma narrows bridge to teach us about rcfa reports and then we wrote our own on other engineering failures, definitely neat to revisit it.

[@qb6025]

2:30 the rods, nuts, and washers have nothing to do with the cause. The two shwellers are placed in wrong position!

[@qb6025]

The original design is inherently flawed

[@lovepandora6550]

A desire to be a guest presenter this month on this channel inspired us to start our own channel, and we have 5 videos already. Thank you Tom!

[@WarrenPostma]

Tacoma Narrows, Hiatt Regency, the history of engineering is the history of failure.

[@kcgunesq]

I was a child when this happened. I had been in that building before the collapse and many times after. It was a rough period for KC. In the same general time period, the roof of Kemper Arena also collapsed, but fortunately, without injury.

[@sabin5162]

Grady is love, Grady is life

[@PracticalEngineeringChannel]

hehtrs sjetn I approve of this slogan

[@karkinissan]

That was absolutely amazingly clear. SciShow did a video on this and it was quite difficult for me to form a mental image about it all. Your video did the trick.

[@SamSpain]

I've watched far worse explanations of this. I'm glad I gave this video a chance.

[@mxskelly]

The only bad thing about this video is I'm already subbed to Grady! Oh well, glad to see him on here, he's a great choice!

[@Skip6235]

I am taking my Professional Engineering Exam this year, and this terrifies me

[@SWIFTO_SCYTHE]

one year ago - how was your professional engineering exam?

[@Bl4ckw0lf1]

To be honest, it should. And I would walk freely around your designs. I just wonder what the designers of galloping Gerdy thought or would think about this event.

[@finddeniro]

Healthy Fears .

[@puirYorick]

This one and the Challenger disaster were IRL lessons that happened during my own university training. Never to be forgotten.

[@chancewebster7953]

40 years ago today

[@sebastianalancliffordthomp4114]

I’m really glad you did this crossover, I’ve been subscribed to Practical Engineering since this video came out

[@zachos-un6py]

i guess this is why the romans had the main "structural engineer" stand under their roman arches when they pulled away the scaffolding, if he didnt do a well enough job, he would be cruched, now *that* is motivation (and feels a little facist, but it probably works)

[@Nevir202]

zachos 2000 In what way is it fascist to have someone be one of the people who dies if they’ve built something that will immediately collapse and kill others?