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.

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

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.

"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.

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

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.

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.

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.

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

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

Planes are designed for wind? Getouttaheeeaarree

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.

"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.

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

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

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

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

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.

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!

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.

"Well There's Your Problem, Engineering Disasters" did a great episode on this.

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.

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

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

Amazing that the road could twist like that

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.

@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!

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

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?

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!

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

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.

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

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

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.

@4:41 The bridge is dancing like crazy and that guy is just casually crossing it with hands in his pockets. Legend!

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

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

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

At least now I know that the gratings between the lanes on the old bridge are there to make it sway less instead of just making it creepy to drive over.

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

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

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!

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.

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.

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

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.

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".

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.

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.

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.

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.

Always great to see a new upload

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 :)

I haven't seen your version yet. I remember watching this on film. A memorable bit was when a man attempted to walk down "galloping gertie" by walking on the relatively stable yellow line. I believe he succeded. The commentator said "Note how Professor Farquarson makes his way down the nodal line." Too funny! Thus, I remember it over 30 years later.

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.

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

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. :)

Absolutely one of the best explanations, technical while easy to understand, thank you.

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

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.

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.

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.

I go over this bridge every day and it’s still amazing

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.

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

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!

That's actually what they did with the replacement bridge, was cut gaps in the road deck between the lanes, and leaving the bare grate for the wind to pass through. The new bridge next to it has a full road deck, but it's much more aerodynamic.

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

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

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

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

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

The Tacoma Bridge is a common example shown in engineering courses

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!

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.

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

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.

I always root for my home town heros. I've moved around a lot but always within a 80 mile radius of tacoma. There is a ton of fascinating infrastructure around the puget sound. Ports of seattle, tacoma, Everett. Naval bases in Bremerton, Keyport, and whidbey cover on, under and above the sea respectively. Bertha finally popped out the other end of her hole in seattle. Just all KINDS of neat stuff if you're keen to look.

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.

4:42 couple of people just casually walking across a collapsing bridge

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

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.

one of the best definitions of vortex shedding I have heard.

More detailed and insightful than my physics class :).

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!

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.

Thank you for the fantastic video. Great demonstration as usual. Would love to see more about the complications and details in creating such a demo!

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

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?

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

In the 1950s there was a strong wind event that started moving the Golden Gate bridge from side to side. They developed a plan to add reinforcements below the road deck. After the reinforcement the concrete road deck was replaced with steel in order to reduce the bridge load. You could notice the lighter part being higher as the contractors moved the replacement along the bridge.

Bridges like the Tacoma Narrows bridge and the golden gate bridge are expensive to maintain because of the salt water.

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.

Now I understand why the Mackinac Bridge has the open gridwork in the center lanes that you can see through.

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

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

Many automotive antennas have a helix around their outside. In the 80's every car had a straight rod for an antenna, but in the 90's makers started adding a helical shape. I doubt you can find an automobile made today that doesn't have a helical antenna shape.

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

It doesn't matter how many hundreds of times I see that footage of Galloping Gertie or how much I learn about materials like steel & concrete, it blows my mind _every single time_ that the road deck has the flexibility to twist & bend to that extent for such a long time before failure - I've lost count of the number of times I've had to explain to people over the years that it wasn't built of timber & it wasn't a hoax!