Why the Tacoma Narrows Bridge Collapsed

[@MarkWarbington]

I recently learned that the tie-down straps on flatbed trucks are given a half twist before they are tightened to prevent resonance from the wind causing the straps to vibrate. For long hauls, resonance vibration can damage the straps or cause the straps to cut into whatever they are securing.

[@WeAreTwoDoorsDown]

And my whole life I've tried to keep my straps straight... Thanks for teaching me something new!

[@madflyer1093]

Yes sir Depends on what I'm hauling whether or not i put a half twist in each side. Usually the longer the strap length without touching something the higher the chance I'll twist it to prevent flutter

[@calebburns4346]

Did you happen to learn that from essential craftsman? That's where i learned it.

[@frollard]

I always have a little giggle when I consider there could be googley eyes on the vibrating straps...just screaming bwabwabwabwabwabwabwabwabwa

[@wambatmqn3833]

unless your in Straya where the scaleys will fine you$$$ if your straps have any twisties

[@JamesCoyle95]

It's impressive how much the bridge could actually handle before failing. Just shows how good the overall design of a suspension bridge is.

[@loganator78r]

@John Ross ya i didn't understand that either.

[@augustreil]

@John Ross, Very flexible. Imagine how much worse roads would be without the serious ability to move around ?

[@dakka7251]

Lasting only 4 months isn't great for a bridge.

[@snoopdogie187]

I think concrete roads last longer than asphalt roads, and there isn't much flex in that material. Asphalt is fairly flexible though, I mean for being a solid looking object anyway. Don't forget, that on the very hot, sunny days the asphalt starts to soften and get tacky.

[@bluebaconjake405]

snoopdogie187 concrete roads are fine at low speed areas. There was a concrete highway where i live and its noticeably not as smooth as asphalt highways. But i think its just the shitty construction that made it rough lol

[@clark57225]

In 1940, my father-in-law Joe Yamamoto was a young teenager who lived near the railroad tracks a mile or so east of the bridge. His school was on the west side. He was there the day the bridge collapsed. Less than two years later Joe, his family and all the other Japanese Americans in the area were rounded up, taken to the nearby fairgrounds, then shipped off to various interment camps throughout the West. Joe never returned to his hometown until 1998 when we embarked on an unplanned RV road trip up the Pacific Coast. Some 55 years since he last set foot in Tacoma, Joe was back in the old neighborhood. He couldn't stop talking about the Tacoma Narrows Bridge. It was a joy to see him relive his big moment in history before the war consumed the entire world. We were further rewarded when we serendipitously stumbled upon a reunion of the Tule Lake Camp internees, where he met so many friends from so long ago. For all my failures as a son-in-law, I feel very proud to have made this trip possible for Joe, my mother-in-law, and my wife. And for this reason, the Tacoma Narrows Bridge holds a very special place in my heart.

[@lizasilomar8545]

Great story about your father-in-law. I would like to suggest an edit, though. Change “interment” to “internment.”

[@randmayfield5695]

Interesting story. Thanks for taking the time to share it. Take care and be safe.

[@westernoperators]

The Japanese American Relocation centers where during WW2. Bainbridge Island was one of the first places to be rounded up, and the one with the most people to return, however your timeline is wrong. At least according to bill's and laws after the end of ww2. If he returned in 1998 it was his own doing.

[@JoeOvercoat]

Awesome story relating another aspect of that injustice. 😎

[@Treklosopher]

@@westernoperators You're not so good at reading huh? Re-read the part about the RV trip ya absolute knob.

[@adfaklsdjf]

"When you push the envelope you have to be vigilant because things that didn't matter before start to become important. Unanticipated challenges are a cost of innovation." This is like Carl Sagan level stuff right here.

[@666Tomato666]

you just are missing "billions and billions" there

[@Tadokat]

Nothing ventured, nothing gained.

[@frankpinmtl]

I think Boeing could have been wise to heed that kind of advice...

[@4FYTfa8EjYHNXjChe8xs7xmC5pNEtz]

you beat me to it... 😂

[@kestergascoyne6924]

That quote really stood out to me. Very true.

[@notjackschannel5380]

Can confirm: Airplanes are in fact designed to aerodynamic loads. (I think) Source: I’m an aerospace engineer

[@nale5126]

Source : Dude trust me

[@t8m8r]

I thought he was making a joke

[@ReflectedMiles]

@@t8m8r Perhaps it was if he was referencing aerodynamic loading generally, but if he was being specific to the causes of this event such as flutter, that is indeed an engineering headache with a long history in aeronautics with respect to control surfaces. From relatively high performance in light aircraft to supersonic transitions, it has been a cause of, or contributor to, many mishaps. Fortunately they are less common now, mostly in overspeed situations.

[@88SC]

Aerospace companies exist to create perfect paperwork, to a precisely forecasted schedule, at or below projected cost. Airplanes are merely a byproduct.

[@freddan6fly]

I really hope you are right when people's life is included as in aerospace. I am a rc pilot and build my own planes, or re-build ARF airplanes. The cheap ones are never built to be flown, and have not been tried out. I can use my ears while standing on the ground to hear flutter from control surfaces and then immediately lower the speed (or crash), and go home and re-build. Some real planes have counter weights on control surfaces to reduce flutter (for instance Boeing 747).

[@calebshonk5838]

I live in Michigan and north of here we have the Mackinac Bridge, which was built four years after the Tacoma Narrows bridge, yet spans almost 5x the distance. The winds between the Mackinac straits are well known for it's variability, some days it will be calm, occasionally it might experience hurricane force winds (and ice, snow, freezing rain and high heat in the summer). The bridge was built utilizing some of the lessons learned from TN. The bridge is equipped with grates in the middle and some aerodynamic buffering on the sides. Additionally, the towers were beefed up and the road suspension was built with a much deeper support system. Even with all that, the road surface will sometimes sway as much as 35 feet from side to side.

[@martawatermanfitnesscoach]

35 feet sway would make me very nervous driving on that bridge!

[@blackholeentry3489]

In 2013, at the age of 72, I rode my motorcyle on a mission to 'bag' the 13 states I had never previously been in before, starting in CA, all the way to the east coast. After reaching the east coast, I first visited Key West, FL, then rode north to Niagara Falls and eventually rode Michigan from the south all the way north to and crossed the MacKinac Bridge. A good length of the bridge is low to the water, no land is visible and at one point, no other vehicles and I felt like I was riding across the ocean. I am now 83 and just recently, gave the motorcycle to my youngest son. BHE

[@Ostsol]

4:08 I pass by a building with chimneys like that every day. I was wondering what the helical veins were for... Thanks!

[@JoeOvercoat]

I’ve been telling everyone those are how gremlins get onto aircraft. And now I know they *also* disrupt vortex shedding…bonus!

[@nobodydoesithalfasgoodasyou]

Even Hampton Court Palace has helical chimneys, though perhaps more for aesthetics than wind considerations 😅

[@RByrne]

They sometimes make them staircases for maintenance.

[@theonewhohonks9675]

Once I was reading old military manuals and in a chapter on formations and marching across territories there was a keynote that mentioned never allowing units to march in formation or in time while crossing a large bridge as the resonance could cause it to collapse.

[@Quintinohthree]

This goes back to the Broughton Suspension Bridge near Manchester, which collapsed for this reason on April 12, 1831.

[@zedex1226]

"Goes back" further. Romans broke step over bridges.

[@Quintinohthree]

@@zedex1226 I need to see your sources on that. From what I found, the British and French only adopted this practice after the incident mentioned above.

[@zedex1226]

@@Quintinohthree *I* would like to see my sources too. I honestly can't remember where I read that or if they were blowing smoke. If my memory for such things were worth anything I wouldn't spend all my time harassing my coworkers for documents. But now I know what I'll be spending the rest of my otherwise leisurely evening looking for.

[@GoErikTheRed]

I find it hard to believe that stone bridges are particularly susceptible to resonance

[@richdiscoveries]

This is exactly why I watch your Channel. I've watched countless documentaries on this bridge, but when I noticed you had a video of it it was a must-see. Explain things so perfectly, so easily understood that someone like me with zero engineering knowledge can completely understand what happened.. Thank you for the effort you put into these videos

[@pufthemajicdragon]

Just a little fan raving - This channel is one of the best things on KZbin and I really wish you could post more often. Thanks for making the channel and for doing what you can.

[@billschlafly4107]

There was a person who was responsible for buying insurance on the TN bridge. He pocketed the money instead because he viewed the risk low...cuz we know everything. He went to jail.

[@TheDecguy]

Bill Schlafly I learned about the insurance scam while I was at University back in 1973. We spent a complete hour of class on it. It doesn’t come up often in discussion about the bridge failure.

[@Rechard1107]

@@billschlafly4107 ewww your last name

[@dudeonbike800]

@@Rechard1107 better than Hitler. And I had to look it up. What's yours? "Zlut?!!!"

[@Looking4RickrRolls]

*Goes to Civil Engineering Internship for 8 Hours* *Goes to Civil Engineering Class for 2 Hours* *Goes Home and Opens Up KZbin* *Sees Practical Engineering and Minute Physics Video* It was a good day

[@MrTeaboar]

Funny stuff that both did kind of the same thing the same day. :)

[@rachaelwang6155]

This is what i aspire to do

[@aviationclub2637]

Engineering is love, Engineering is life :D

[@brandy1011]

Airplanes designed for wind loads? That's certainly just a myth propagated by Big Aero :-P

[@conspiracyscholor7866]

Indeed it is. Natural sustained flight is impossible due to natural physics. "Flight" is created through illusionatic magnetism, when you get into the flat, disk earth theories of magnetism you will see that electrons do not exist in any case.

[@kylebutzerin7803]

r/whooooosh

[@jwfleming1024]

@@conspiracyscholor7866 name checks out

[@NublaNukes]

“// a mod over at r/flatearth, genius iq of well over 145...” ~ @Conspiracy_Scholar

[@AndrewJJ-0114]

I want to eat a big Aero.

[@seancpp]

Grady, your content is seriously some of the best stuff on here. You bring very complex topics down to earth for us to understand, and your material is also very binge-friendly. Thank you

[@alex0589]

Planes are designed for wind? Getouttaheeeaarree

[@arthas640]

As someone from Tacoma; you'd be surpsied how often builders from the Southwest buil things here and dont take into account *rain*

[@doggo00]

heare ey?

[@nomore6167]

What I find most amazing about that Tacoma Narrows Bridge video is not the way in which the bridge failed, but the fact that the vertical motion and twisting didn't cause the deck to break apart long before the cables failed. We non-engineers typically think of concrete as completely rigid material, but that video shows quite a different story.

[@coryman125]

I can't help but like this channel- it's just straight up engineering, no clickbait, or anything of that nature. Just engineering and googly eyes.

[@ootommo1]

The effort you go to in all your videos is simply amazing. Thanks for great quality videos that are interesting and make you think about things I wouldn't have other wise.

[@4FYTfa8EjYHNXjChe8xs7xmC5pNEtz]

"When you push the envelope, you have to be vigilant, because things that didn't matter before suddenly start to become important." Exactly. This is a fairly profound statement and can apply to almost everything in life, not only engineering problems.

[@WokeandProud]

Learn from your mistakes and never repeat them ya it applies to everything.

[@betsykeller9096]

As the daughter of a former Chief of Aerodynamics for Naval Air Systems Command, I can remember going to Lakehurst and seeing model propeller variations on a large board that were monitored for how they handled wind resistance. It was the coolest thing I'd ever seen. And, I enjoyed learning about Engineering failures that led to engineering successes. Thanks for the lesson!

[@pjcanfield8]

“And our next episode is on the Tacoma Narrows Bridge disaster” Alice: “That’s right”

[@Gianluca.bernardi]

Man. Your videos are the best. I learn a lot here. Sorry about my english. Greetings from Brasil.

[@Quintinohthree]

People who do apologise for their English rarely should and people who should apologise for their English rarely do.

[@Nitrxgen]

Anyone know what Gianluca said? it's impossible to understand! Brother, you typed perfect English and you know it, why apologise? lol

[@MABFR01]

When I started speaking English, I would apologize about it too, reason being that the grammar nazis in the comments would trash talk immediately, even though I was French and I was making huge efforts at the time to speak their language. Sorry for my English

[@mahuk.]

As a native Spanish speaker I made the same thing apologizing long ago. It is just like Marc-Antoine said. We might be sure that we know the words, but grammar is another whole different thing considering most of us learned English by ourselves and never really took a decent class in our lives. Edit: sorry for mai Ingurish

[@atatatatatagsad]

@@mahuk. your ingurish is pretty good

[@gmcjetpilot]

Mechanical Engineer and when in undergrad studied this. Vibrations was one of my favorite classes. Coincidentally my first Job after graduating was Boeing in Seattle near Tacoma narrow bridge. It was rebuilt and exists today.

[@Shmozone]

I cross the narrows every week, you can see the solutions you mentioned at work on the newer bridges. The replacement bridge was built in the 1950s and uses steel grates in between each lanes like the solution at 5:56. In 2007 a second bridge was built alongside the original to handle the increased traffic, but I can't find as much information about how this new bridge combats the wind. It doesn't have any holes in the deck though. Either way was interesting to learn about this stuff.

[@REDandBLUEandORANGE]

Amazing that the road could twist like that

[@Helperbot-2000]

Yeah

[@dudeonbike800]

Those of us have seen same during earthquakes in seismically active places. Bizarre for sure!

[@timothymclean]

Huh. You mentioned mass dampeners and the like, which minutephysics also did a video about today. Today isn't Mass Dampener Appreciation Day or something, is it?

[@kuronosan]

They even both used the same stock photo of powerline damper.

[@maybesomeothertime2913]

Well, i really should be...

[@blauw67]

Great coincidence

[@mrslinkydragon9910]

Ikr... but this channel did it better ;)

[@damussnochderstecker]

Practical Engineering can't have done it better than minute physics because they talked about completely different topics. Grady talked about bridges and Henry about TMDs. Bothe videos are fantastics as always though. :)

[@BenscoterFamily]

Great video. I remember reading about the flutter problems on early designs of the F-15, giving rise to its characteristic dogtooth in the horizontal stab.

[@frostrap]

I drive over the narrows bridges frequently. There are two now and the older of the two has a gap in the middle that you described! I have wondered for decades why that gap was there and I always assumed it had to do with weight, but it’s for aerodynamics! So cool!

[@darkdrgn000]

This was covered when I did my engineering diploma. Every civil engineer in world has learnt about this lesson in bridge design

[@peterschmidt-nielsen3577]

Oh man, I wrote the fluid simulation that you show at 3:43! I wrote it when I was 17 (twelve years ago) from scratch in C to try to better understand how CFD packages work -- I basically just implemented Jos Stam's famous Stable Fluids paper, except I used FFTs to perform the Helmholtz decomposition (he suggests using a Poisson solver instead). I uploaded the clip to Wikipedia, which is I assume where you got it from. That was VERY jarring to suddenly see something I made 12 years ago pop up! Super cool, made my day! You can actually see some subtle artifacts from my choice of FFT-based Helmholtz decomposition -- the simulation effectively has slightly periodic boundary conditions, which is why the fluid flow in *front* of the no-slip cylinder starts wiggling too, not just the fluid downstream. This is an artifact of the simulation, and doesn't occur in a real Kármán vortex street.

[@Fs3i]

I heard about this on the "We'll there's your problem" podcast. I heard they're talking about this next week. Very excited.

[@sharonrad3317]

This was nicely done, thank you. Came across it because of a news item today of a bridge in China having to be shut down for oscillating and it reminded me of Tacoma Narrows. I really appreciate your point at the end that we always need to approach innovation with a certain degree of humility, since we don't know what we don't know until perhaps it's too late.

[@Lillireify]

I absolutely love your videos. It's amazing how easily you can explain complex matters regarding engineering. I wish I had such help when I was studying to be civil engineer :)

[@lidarman2]

This is an excellent video on this subject and thank you for the demonstration. I remember studying this in Engineering school but we basically watched the video and concluded it was resonance but no other details were discussed. I like that you went deep into the details of how the wind energy gets stored in the bridge dynamics.

[@Hemomancer]

Are those googly eyes on the bridge model? I love those details!

[@zvpunry1971]

Not only on the bridge model, also on the model showing the tuned mass damper: 6:08 And that's from a video that is more then 2 years old: kzbin.info/www/bejne/nGK4ZYZ3nN5pZsU The googly eyes also appear on other videos.

[@Hemomancer]

@@zvpunry1971 it's like learning a new word. I noticed them everywhere after noticing it there. But thank you. :-)

[@o0dhew0o]

@Practical Engineering the quick poke at airplanes @ 6:40 is just the type of classic, dry, engineering sarcasm that make your videos so great. Very educational as always, keep up the great work!

[@jordanfstop]

Grew up driving over the newer bridge(s), thanks for this video! It was always one of my favorite historic moments around here. Fun fact: nobody was killed, except one dog, Tubby, who refused to leave his car, but the state paid the owner like $14k in today's money for his car and dog.

[@dldave1978]

Grady - found your stuff a few weeks ago and watch a couple videos a week. I appreciate your efforts that go in to the videos. Especially, the models and such, that are built to help visualize the concept. Have heard of the Tacoma bridge collapse my whole life but never knew the ‘why’ or ‘how’.....I find that with a lot of your stuff and learn a lot. I even have my kids watching with me. They love it! Thanks for everything!

[@TheComedyButchers]

Always great to see a new upload

[@FearableBucket]

I love Grady's videos for one simple reason; He takes complex ideas/concepts, and molds them into simple, easy to understand videos. Amazing job, as always, Grady!

[@jackfrost1031]

The antenna on my truck has spirals for the same purpose. I've never seen a chimney that tall but it makes sense.

[@bgdwiepp]

This is not the primary reason for the helical antenna section, that section has the effect of adding inductance to the antenna and is referred to as a "Loading coil", that simple put, allows you to make an antenna smaller for a given RF frequency.

[@jackfrost1031]

bgdwiepp interesting comment, especially considering the antenna in question has got to be 3' long. I've never seen spirals on those little stubby antennas. I wonder why not?

[@om617yota8]

@@jackfrost1031 The spiral was probably inside the antenna. Also, the higher the frequency = the shorter the antenna. Depending on the band a full 1/4 wave antenna may only be a few inches long.

[@sylviahacker6695]

Great video, very enjoyable to watch and educational. I've seen those spiral things on chimneys and often wondered what they were for. And the googly eyes on your demo bridge, a great touch! Thanks for taking the time to make this.

[@FuncleChuck]

That model was astonishing! Amazing how simple it would have been to see the problem if the engineers had been aware.

[@catfishmudflap]

My structural engineering professor showed us the historic Tacoma Narrows Bridge video on the first day of his class. You did a great job explaining the phenomenon.

[@SongOfStorms411]

Thanks for the great video! I remember when the Mythbusters "busted" the scientific principle of resonance causing a bridge to fail, simply because neither one of them actually understood what resonance meant. That was really a face palm of an episode.

[@AnthonyFrancisJones]

I am sure it has been mentioned but I always point out to my students that if you watch the torsional oscillation before failure it is interesting to see the lighting poles are moving 'piecemeal' an indication to young students that they have a different natural frequency which they are not being driven at. We had a building by our lab with a lose roof section and the noice from the aerodynamic flutter was a constant reminder of physics at work! Great video - many thanks for making them.

[@PendragonDaGreat]

I live just north of Tacoma. If you go to the Point Defiance Zoo you can actually see a part of the old bridge in the aquarium. It was brought up when the "New" (third) bridge was built and is now used as part of the "waters of Puget Sound" exhibit.

[@olafueberschar339]

Awesome video! Thanks a lot making and sharing it - also for your almost philosophical thoughts at its end, definitely being motivating for any engineering student around the world. I will recommend this to my students.

[@Aphelia.]

5:20 I love how this little piece of bridge has googly eyes that's so cute

[@RandyK1ng]

I did, in fact, see this first in my "Strength of Materials" class at Ohio University in the 1970's, so none of this was new. HOWEVER, I never knew what those silly spirals were on chimneys. So no matter how much you think you know, when you're open to hearing something new, it just shows up. Thanks, Grady.

[@TheGerm24]

I was really excited to drive over the existing Tacoma Narrows bridge this summer.

[@chadportenga7858]

Thank you for this simple explanation and the demonstration with the fans. I have traveled over the Mackinaw Bridge too many times to count, but I remember that it was designed with features to combat the wind that were directly derived from the Tacoma Narrows Collapse. I didn't know what they were, but now I do - primarily, it's the grating of the center two lanes. Very interesting, and just a couple years ago, I was able to boat beneath it - what a sight to see! You don't realize the size until you're below the Mighty Mac!

[@Ikantspell4]

I'm no enginerd but I'll go out on a I'm and certify them aeroplanns are designed to handle wind loads

[@freddan6fly]

Found this channel today, and this specific video. Thanks I "always" new that the Tacoma bridge changed how we construct bridges, and also that the London millenium bridge (which I happen to walk on early after opening) made us re-think walking bridges. Thanks I hated mechanical engineering in university due to a bad teacher, and am eager to learn more.

[@acivilconversation18]

Great video, very interesting. I love how you build models to help with the visualisation. I remember they had the resonance issue with the Millennium Bridge in London when it first opened. They had to subsequently install mass dampers underneath the bridge which you can go and see which is really cool. :)

[@RealZynexx]

We recently used this video in my Physics class and I shouted out “I know this channel it’s great!”

[@ArresChang]

at 5:41 "too much stress in the suspension cables" is incorrect. The element which initiated the collapse was the edge plate girders which failed and unzipped. The suspension cables were still in tack during the initiation of failure.

[@JoeOvercoat]

I picture the cable manufacturer trying to explain this over and over as they descended into alcoholism because no one would listen.

[@Werdna12345]

I wish there was an Electrical equivalent of Practical Engineering! So good!

[@igfoobar]

When you push the envelope, sometimes the envelope pushes back.

[@atomicwedgie8176]

It wants the stamp rubbed on it's skin.

[@DeathByLego]

Or else it gets cut open again.

[@CreepAM]

I freaking love you Grady. Your videos are so well made, informative, and enthralling. By far my favorite channel on KZbin

[@Rulerofwax24]

This video made in collaboration with Minute Physics. It wasn't all that similar, though I'd never heard about those dampers on power lines until today when both of you mentioned them. They're a good, kinda funky example though, so it makes sense

[@samuellourenco1050]

Loved the demonstration of aeroelastic flutter in motion. No doubt, your channel has quality and deserves more subscribers. Keep up!

[@justinokraski3796]

Is this the famed Tacoma Narrows bridge episode of the "Well There's Your Problem" podcast???

[@RoamingAdhocrat]

No, that's going to be their next episode…

[@mfThump]

@@RoamingAdhocrat patreon exclusive too, it's even been delayed since uhhh *last month*

[@BicyclesMayUseFullLane]

Better donate to bail fund now to get the bonus episode forever :p

[@philtroehler407]

You provided an understanding of this phenomenon that few have been able to give me. Thank you.

[@Petch85]

This is just the best. Love you scaled models. Hope you remembered the reynolds number when scaling :-). Also "Interesting" = "enormously difficult" for those non engineers out there. And "enormously difficult" = " many assumptions" for those engineers out there :-p

[@SulfuricDonut]

I think "hang the thing and crank up the fans until something cool happens" is appropriate scientific procedure here. Proper Reynolds scaling would only really be necessary if someone was planning on using this research to for a full-sized googly-eyes bridge and that might not be a great use of taxpayer money.

[@Petch85]

hehe... Yes it is absolutely fine. :-) But if its worth doing, its worth overding. Thus bridge to scale and "proper" reynolds scaling it is. What wind conditions might there have been. Analyse the movement of the bridge... Maybe this is way my youtube channel still have 0 videos :-)

[@bigmikeh5827]

Petch85 Agreed. For my industrial Electrical students “seeing is believing.”

[@JoeOvercoat]

@@SulfuricDonut No. The slot especially is going to be sensitive to the Reynolds number. I think the important thing is that he’s not trying to model that bridge and he’s not saying putting a proportional slot in that bridge would’ve solved the problem necessarily, rather that it is best practice now for reasons demonstrated with the model.

[@TheZombieSaints]

A picture truly is worth a thousand words and your little models you make are proof of that, Love 'em. awesome video once again.

[@Garebare1]

Can you discuss about the recent bridge collapse the Genoa bridge?

[@StrongMindandBody]

Excellent point you made on how important it is to be reminded "of how profoundly capable we are of making mistakes."

[@rodchallis8031]

I cannot remember the source of information, but I am sure I read that the grating in the road deck of the Mackinac bridge that joins the upper and lower Michigan Peninsulas included grating in sections of the road bed as a direct result of the information acquired from the Tacoma Narrows bridge failure. I may need suspensions for that sentence. Anyway, I've been over that bridge a few times. What a marvel.

[@rodchallis8031]

Last days of '70, or the first days of '71, we traveled from London, Ontario to Sault Ste. Marie, Ontario. It's quicker to go via Michigan and across the Mackinac Bridge. I was 10, in the back seat of my Dad's '69 Valiant, watching my Uncle drive his big car behind us. There was a storm that day that started out as wet snow, then the temperatures dropped turning the packed snow to ice on the roads. On the paved sections of the bridge, I swear I saw my Uncle's car hit the tire high guard rail a few times, pushed by the wind on the ice. But, memory that old is pretty malleable, and ten year olds tend to be dramatic. But....

[@Jo_Wick]

I love your videos through a combination of liking the source material and your well-thought-out videos. While I liked the videos when they were a bit longer, you still have exceptional content on your channel.

[@fixpacifica]

I used to live in Seattle and must have met half a dozen people who claimed to be the last person off the Tacoma Narrow Bridge before it fell down.

[@lesflynn4455]

I've just discovered this series. I'm loving it.

[@logicalfundy]

More detailed and insightful than my physics class :).

[@conradp.woodturning972]

About a year ago I researched the Tacoma Narrows Bridge for an engineering assessment, and it's very interesting how even moderate wind could have such a devastating effect on the bridge, just because the frequency of the wind matched that of the bridge! Thanks for the great video and explanation :)

[@Swagaito_Gai]

This is the information you'll never get from the Well There's Your Problem podcast.

[@freemanc6258]

My five year old son enjoys and is fascinated by your videos although he can hardly be described as fluent in English. Science and your charisma talk! 😀

[@dcaonoek]

Aeroplane wind load 101 - When landing, on a good day most of it comes from the front. On an average day you’ll get some from the side. On a bad day it’s coming from the back. On your last day it’s coming from overhead.

[@volodymyrhavrylov7993]

I saw this (bridge) video tons of time, and it was always about resonance. But here you really explain why the thing was being _twisted_ instead of just oscillating, and that is so cool! I have asked this question - why twisting, not vibrating - for a long time, but without any decent answer. Thanks! Also it was great to know about the helix structures around large chimneys, I saw a lot of them around, but thought it is related to some fancy strengthening of the pipe itself; had no idea it protects the pipe from wind-caused oscillations. Probably, that's a good reason why this helical structures often are located only at the topmost part of the pipe - because the wind effect is most powerful at the end. Great video!

[@angry4rtichoke646]

Thank you for making these videos, I always look forward to watching them! I live in Washington, but when we learned about the Tacoma Narrows Bridge we never went into depth about the cause of the failure, so I assumed resonance. I have a question about fire hydrants, and their infrastructure. I've heard there's a mandated range for them in cities (300 feet spacing?), and I wonder what would happen if you opened multiple at the same time (would the pressure be affected, or are different parts of the city separately linked?). It might make for a fun video!

[@mulberryfarms6848]

Grady, your subject matter is fascinating and your manner of presenting it is both engaging and deeply informative. Watching your videos takes my level of understanding from "why on Earth?" to "Aha! That makes sense!"

[@KurikuShoTto]

I heard that Well there's your problem podcast is covering this next week

[@AV1461]

Through out the last two weeks I thought more about vortex shedding more than usual and now Practical Engineering launches a video talking about. Life is weird sometimes.

[@davidbuschhorn6539]

It seems like nearly all of the major "engineering failure" videos have the same sort of thing in common. The guy holding the purse strings cheaped out after construction began.

[@arthas640]

washington has sort of learned their lesson, now we spend as much as humanly possible on projects like this!

[@PrincessSixThirteen]

Actually, not in this case. The design was specifically created to suit the budget. It was the narrowest suspension bridge designed and was actually quite celebrated for it's innovative design.

[@jockellis]

Since when did politicians worry about spending our money? Some tv show I watched about 20 years ago stated that after the George Washington Bridge was built engineers had their own goal of making them lighter. IIRC, the show said that the farther west you went the lighter the bridges were.

[@melissanichols784]

Except that the original design also included an open lattice truss system that would allow wind to pass right through. It was the construction company that cheapened out by using solid panels instead (likely to pocket the difference). If they'd stuck to the original design, the bridge would not have collapsed.

[@gtw4546]

More like overestimating the innovation (whether new materials or new designs) combined with a failure to realize that they are unproven. I'd chalk these failures to human hubris.

[@almostfm]

when I was in college, my Physics 1 professor had a great rig for demonstrating resonance in structures. Because it's California, he used a "building" to demonstrate resonance in an earthquake. The building was a three-story affair about 2 1/2 feet high. Fairly flexible sides made out of sheet metal, and each floor was a piece of wood with screws going through the sheet metal to anchor them in place. On top was an electric motor that had a stopper from a flask with an off-center hole on the motor shaft, so it would vibrate. He also had a strobe hooked up and a control that governed the motor speed and the strobe speed. He turned the motor on at a low speed and the "building" shook. So he sped it up and the building began to sway as a unit. A little faster, and it went back to a shake. A little faster and the floors started moving opposite directions. It was fascinating to watch as he talked about what was going on. Suddenly there were several loud bangs, and the whole thing collapsed in a pile. It turned out that letting it run for an extended time at the "floors moving opposite directions" speed put enough stress on the screws that they pulled out of the wood and it collapsed. He looked at it for a moment and said "Well, I didn't expect _that_ to happen".

[@Horstroad]

Aircraft use their fuel from the inboard tanks first, then from the outboard tanks. This not only reduces the stress on the wing root, it also reduces flutter as there is more mass concentrated on the wing tip, ergo more energy is needed to get the wingt tip moving. The MD11 for example transfers fuel from the tip compartment to the inboard compartment only when 70% of the fuel in that tank is used up. At this time there is as much fuel in the tip compartment as is in the inboard compartment.

[@UnbeltedSundew]

Well it's also sloshing around through the baffles, making it a natural dampener. Not just the weight.

[@Horstroad]

UnbeltedSundew Wing flutter is a vertival movement, while fuel sloshing is horizontal. This shouldn't play a big role

[@UnbeltedSundew]

Hmm... Perhaps I had it confused. I think I got the thought from this video by Mentour Pilot: kzbin.info/www/bejne/jKHdhpWPmt1nmskm6s He doesn't actually mention dampening action from the fuel at all in the video though. And if one thinks about it, depending on fuel to dampen the vibrations would actually be a prety bad way for engineers to approach the solution (making a plane so that it's flight characteristics get much worse over the time in the flight). I think maybe there is no need for a dampening force against air current because of the nature of the functions of the wings in the first place (manipulating the air flow and speed in a very specific way so that it creates a low pressure area above the wing to make lift).

[@finianholland7654]

Please keep it up with the vids. As a civil engineering major I love these.

[@JoeEls]

Aircraft do experience flutter. Smaller aircraft like a Cessna typically have counter weights in the control surfaces to limit the impact of flutter.

[@t8m8r]

Was it a joke when he said he can't confirm?

[@iamneophyte]

I had this in my physics class while tackling the topic of oscillations and waves. Mad interesting.

[@toniklemm1172]

1:04 Yay, footage from Dresden, Germany! 😀 I lived there for many years! Out of curiosity, why did you use this in particular, and where did you find it?

[@naota3k]

Awesome video as always, Grady. I used to be fascinated with that Tacoma Narrows footage when I was a kid, and I never knew what it was from!

[@tcb268]

Watching the collapse isn't the same after learning there was a little girl's dog in that car. RIP Tubby.

[@tink58bell]

But screw everyone one else right?

[@tcb268]

@@tink58bell everyone who? Nobody else was hurt.

[@longboi2044]

@@tink58bell yes

[@operationd--msday]

@@tink58bell yes

[@PlasmaHH]

Funny thing how the bridge was used in the 80s physics courses in school and still in the modern world of youtube this is the best example we have.

[@A3Kr0n]

No! I'm not going to watch another "Why the Tacoma Narrows Bridge Collapsed" video. I've been watching these since I was in school back in 1983! :-)

[@mysteriouslykind955]

My mom was born that year

[@KumaCarter]

This is a very well produced video. Glad to see perfectionists excelling

[@DomashnieSamodelki]

*Good video. I found a way to stop the meter with a piece of wire and lower the electricity bill*

[@News247-m9v]

Thank!

[@SuperFredAZ]

It just goes to show how brilliant the Brooklyn Bridge is. Built so the 1880s for horse and carriage, holding up to loads 4X the average back then. Interesting example of what not to do.

[@NeoRipshaft]

Oooooooooooo - I wondered why those helical bits were present on all the big chimneys on campus - my best guess was heat baffles or structural integrity (rigidity), but that didn't make sense because I doubted they would serve well in that capacity, on either front. Now i know! And knowing is half the battle. G.I. Joe. Yo Joe!

[@automaticmattywhack1470]

I've already seen several short documentaries about the Tacoma Narrows Bridge collapse, but for some reason, I'm betting Grady's explanation will be better than all the rest. After I watched the video: Yep, it was better. Thanks, Grady!

Can you make a video of educated guesses about the Italian and American bridges which recently collapsed? I would love to see your take on them. As they happened AvE tried to analyze it and the discussion is helpful I think.

[@mrnsnp]

Always love watching your videos. Some days I have to remind myself to study over watching your videos.