Speaker 1: Hello, s y s K Fam. It's Josh and for
Speaker 1: this week's Stuff you Should Know selects. I've chosen Bridges
Speaker 1: Nature Abhores Them, which we released back in June of
Speaker 1: two fift and it's a pretty good one. It's got
Speaker 1: a lot of engineering, believe it or not. But it's
Speaker 1: not like the eye glazy kind. It's like the oh
Speaker 1: my god, this is amazingly fascinating kind. I hope you
Speaker 1: feel that way at least, and I'll bet you will
Speaker 1: so enjoy Bridges Nature Abhores Them. Starting now, welcome to
Speaker 1: Stuff you Should Know, a production of I Heart Radio. Hey,
Speaker 1: and welcome to the podcast. I'm Josh Clark with Charles
Speaker 1: w Chuck Bryant with Jerry Rowland with me Josh Clark,
Speaker 1: and this is You Should Know featuring Josh Clark's about
Speaker 1: to say, you never introduce yourself, and then you done
Speaker 1: did it twice? Three three times? Oh yeah, you always
Speaker 1: introduce your but you never say your last name. I
Speaker 1: think that's extruct me. John, No, I say I'm Josh Clark,
Speaker 1: do you Yeah? Every time I should listen to these sometimes, yeah,
Speaker 1: that explains the glazed overlook in your eyes. Whenever we
Speaker 1: start um Bridges. Yeah, is that your intro? Yep, I
Speaker 1: like him. Maybe we can add like a scat drummer
Speaker 1: on top of that. We have that kind of um
Speaker 1: when we're doing uh listener mail, there's a little bit
Speaker 1: of dan Oh yeah, well that's not scat drumming. I
Speaker 1: would say that's more of a shuffle mhm scats like
Speaker 1: bood Yeah like that. Yeah, you should get Hodgment to
Speaker 1: scat for you sometime. He's going He's get a lot
Speaker 1: of boot boot badus going on when he's scatting any
Speaker 1: jazz hands. No, No, it's not exactly Manhattan transfer level.
Speaker 1: He's intermediate. Yeah. Uh yeah so again Bridges. Yeah, you know,
Speaker 1: I bet we're going to hear from some folks because
Speaker 1: there are bridge enthusiasts Yeah, which I think is kind
Speaker 1: of neat. Yeah. Well, I mean they're like modern marvels
Speaker 1: of engineering, and actually there's some ancient marvels of engineering too,
Speaker 1: as far as they are, um, yeah, they're basically I
Speaker 1: was talking to our pal um Adam the architect o,
Speaker 1: the bridge builder. No, uh, he's a building builder or
Speaker 1: a building designer. I don't know if he actually knows
Speaker 1: how to build the buildings. He just knows how to
Speaker 1: tell other people how to build that. Adam can't swing
Speaker 1: a hammer, so he was saying that, um uh the um.
Speaker 1: Basically the structural engineers who designed bridges are just straight
Speaker 1: up geniuses. Like it requires a basically a genius to
Speaker 1: to factor in all of this stuff. Yeah, anyone can
Speaker 1: design a building, you know, there's just four walls and
Speaker 1: a bunch of floors. Put a roof on it. Bridge
Speaker 1: though it's different. Yes, right, there aren't walls really, Um,
Speaker 1: there can be bridges of Madison County they had walls.
Speaker 1: Oh yeah, they have walls. I was going to mention
Speaker 1: the bridges of Madison County. Yeah, I love those that
Speaker 1: that'd be a beam bridge, I guess, yeah, with a truss, right,
Speaker 1: a top trust, what's the top trust called a through
Speaker 1: trust through trusts, and then below that. If it were
Speaker 1: below it would be a deck trust. But I don't
Speaker 1: know if that counts as a trust. It's more just
Speaker 1: like a house on top of the bridge. I bet
Speaker 1: their structural support there. I guess they thought it was
Speaker 1: mainly just to keep the rain off of you when
Speaker 1: you crossed the bridge, like just an extra little thank
Speaker 1: you for crossing the bridge. I thought it was just
Speaker 1: to draw in Lackey tourists who wanted to have their
Speaker 1: picture made. Another famous bridge, the one that the headless
Speaker 1: Horseman couldn't cross in the Legend of Sleepy Halla. Oh yeah,
Speaker 1: it wouldn't that a bridge. Sure, trolls of under bridges,
Speaker 1: bats drawbridges are pretty cool. Have you ever seen Maximum
Speaker 1: Overdrive the beginning of that movie. Um, it's been many
Speaker 1: many years. I saw it again. I saw it again
Speaker 1: very recently, like this year, and it is it's maybe
Speaker 1: better than it was before. It holds up as a
Speaker 1: crappy movie still. Yes. Yeah. The whole soundtrack is a
Speaker 1: C d C by the way, which you should love
Speaker 1: the whole soundtrack. I do love that, and I do
Speaker 1: remember that. And didn't Stephen King directs that, which he
Speaker 1: doesn't do much right. No, that maybe it's only one
Speaker 1: is definitely his first interesting. But there's a great draw
Speaker 1: drawbridge scene in there. Did someone jump it, jump the
Speaker 1: span as it raised? No, I think their car fell
Speaker 1: into their truck fell in. Okay, because usually the drawbridge
Speaker 1: scene is like I can make it. Uh No, this
Speaker 1: one was You're all doomed and uh. Let me also
Speaker 1: recommend Budapest for bridges. You mean I went to Budapest
Speaker 1: a couple of years ago. Yeah, I went there like
Speaker 1: twenty years ago. Okay, so yeah, you know the bridges
Speaker 1: are amazing that I think like five because they connect
Speaker 1: the two sides. Yeah, Buddha and Pesht, right, and each
Speaker 1: one is totally different, like it's just a completely different design. Yeah,
Speaker 1: and they're just all gorgeous. Yeah, let's just start with
Speaker 1: a bunch of bridge recommendations. I'm going to recommend the
Speaker 1: city of Pittsburgh. Oh yeah, I went through a baseball
Speaker 1: game there, and it's just just gorgeous. Those beautiful bridges
Speaker 1: that you can see from the baseball stadium and the river.
Speaker 1: That was when we were a Toyota commercial from its ring, right. Yeah,
Speaker 1: I stayed in the hotel and just eight um sog
Speaker 1: copenny r no chicken sog. Right, it's just like a
Speaker 1: chord of it. But you can see the baseball stadium
Speaker 1: out your hotel window. Yeah. And I saw some bridges too. Yeah,
Speaker 1: you walk across the bridge to get there. Really, swe
Speaker 1: did what else any other bridges? Well, Brooklyn Bridge, sure,
Speaker 1: Golden Gate Bridge, those are like the famous ones are
Speaker 1: barely even worth mentioning, Yeah, but the Brooklyn Bridge is
Speaker 1: for your money. It's which is free. It's a pretty
Speaker 1: great thing to do to walk across it. It's it's
Speaker 1: just beautiful. I've never done that. You should do it.
Speaker 1: Even the Geico Lizard did it, and I haven't. That
Speaker 1: guy's like Australian or something. Well, maybe we should just
Speaker 1: animate you and have you walk across it. Uh. One
Speaker 1: more thing, if you want to know more about the
Speaker 1: Brooklyn Bridge, I don't remember which one we talked about
Speaker 1: it and but there is a really cool documentary about
Speaker 1: the Brooklyn Bridge and it's building by Ken Burns. Oh wow,
Speaker 1: I believe it's on Netflix. I'll have to check that
Speaker 1: out then, yep, because I like kin Burns and Brooklyn bridges.
Speaker 1: All right, you ready? Uh yeah. In so, bridges have
Speaker 1: been around for a very long time. This article is
Speaker 1: by Robert lam and another dude named Michael Morrissey together.
Speaker 1: I believe they were locked away in a closet for
Speaker 1: like a couple of months while they worked this out together. Well,
Speaker 1: he the one of the first ones that're talking about
Speaker 1: ancient bridges that they mentioned in here. The Arcadeco Bridge
Speaker 1: in ancient Greece, did you see that thing? It's really neat.
Speaker 1: I mean it still stands. It's a three thousand year
Speaker 1: old bridge, and uh, it's just kind of cool to
Speaker 1: think about. You know, ancient civilizations. In ancient times, people said, well,
Speaker 1: I want to get over there, right and I'm here,
Speaker 1: and uh so let's build something to do that. I
Speaker 1: need something to walk on, yeah, or drive my card over?
Speaker 1: Is that simple? Um? I saw that. I saw the
Speaker 1: world's oldest bridge that's still in use, um Is in
Speaker 1: Turkey over the um Melis River, I believe, from eight
Speaker 1: b c. Do you know what that one's h How
Speaker 1: it's constructed a single It is a single stone slab archy. No,
Speaker 1: it is a stone slab, single arch. Yeah, that makes sense,
Speaker 1: very basic. Yeah, but the arch it's super old. But
Speaker 1: it's still in use today because whoever figured it out
Speaker 1: came upon this very elegant solution to a lot of
Speaker 1: problems that a bridge poses. Because, as you were saying,
Speaker 1: when when you come upon like a river or creek
Speaker 1: or something, you say, I'm on this side and I
Speaker 1: need to be on the other side, so I need
Speaker 1: something to walk across. Yeah, Okay, that's a basic solution.
Speaker 1: But the further and further you get, the more and
Speaker 1: more problems. Like as bridge billers say, most span more problems. Yeah,
Speaker 1: I guess what we should have said is I want
Speaker 1: to walk across and live. I want to walk all
Speaker 1: the way across, right, I don't want to fall down. No,
Speaker 1: I don't want to get halfway across and have it snapped.
Speaker 1: So over the years, as people have come upon problems
Speaker 1: where you are going to build a bridge that will
Speaker 1: snapping and kill you, they've come up with solutions to
Speaker 1: prevent that from happening. That's pretty much the pursuit of
Speaker 1: bridge building is coming up with ways to prevent a
Speaker 1: bridge from collapsing, and a lot of trial and error
Speaker 1: over the years, you know, and a lot of real
Speaker 1: significant disasters. In fact, there's a Time magazine slide show
Speaker 1: um called worst Bridge Collapses in Past one years, um,
Speaker 1: and it's got all these photos of collapse bridges and
Speaker 1: little descriptions and the number of fatalities and everything. But um,
Speaker 1: it's it's really interesting all these different bridges have collapsed
Speaker 1: and failed for all these different reasons. Well and after
Speaker 1: each one, uh it's very sad, of course, but after
Speaker 1: each one someone goes, oh, well we should do this
Speaker 1: for the next one. We should not forget that bolt
Speaker 1: next time. Well, that's that could be human Ara, True,
Speaker 1: that's happened. Yeah, I'm sure. All right. So should we
Speaker 1: start off with the bats? Be a t s. Beams, arches, trusses,
Speaker 1: and suspensions are the main components of the structural components
Speaker 1: of a bridge. It's very simple. That's it. That's all
Speaker 1: you need to know to construct your own bridge. And
Speaker 1: with these four things you can make almost any kind
Speaker 1: of bridge. Um, we're gonna cover mainly beam bridges, arch bridges,
Speaker 1: trust bridges, suspension bridges, and then the super cool looking
Speaker 1: cable stayed bridge. It is super cool looking, probably my
Speaker 1: favorite looking bridge in the world that I came across
Speaker 1: and reach researching. This is a cable stayed bridge, the
Speaker 1: one that's in the article. Oh yeah, they look like
Speaker 1: look like sales gorgeous, the big triangles rising up. It's lovely.
Speaker 1: But they look a little more modern to me. They
Speaker 1: don't have that classic architecture like the Brooklyn Bridge does,
Speaker 1: or like the Tower Bridge in London. Yeah, I think
Speaker 1: that's why I like it. Yeah you like the modern look. Yeah, yeah,
Speaker 1: you're a modern guy. I'm super mod alright. Um. They
Speaker 1: point out in the article, which is very key. What
Speaker 1: you talked about. The span of the bridge is the
Speaker 1: distance between the supports, and that's where Um, that's where
Speaker 1: it all goes down. Basically, Yes, that's got to be
Speaker 1: strong there. Those are something that every single bridge has
Speaker 1: is a span and at least one support most likely
Speaker 1: to yeah, you know, um, and there's different The reason
Speaker 1: that there are different types of bridges because different bridge
Speaker 1: designs that that bats designs what is it, beams, arches, trusses,
Speaker 1: and suspension. They provide stability for varying span lengths. So
Speaker 1: like a beam, if you have like a fifty ft
Speaker 1: UM span, just put a like a very long log
Speaker 1: over over the span and there you go. There's your bridge.
Speaker 1: But as you get further and further along, you have
Speaker 1: more and more problems supporting that span, So you need
Speaker 1: different types of solutions, and the different length of the
Speaker 1: span calls usually for a specific type of bridge design. Yeah,
Speaker 1: and generally it'll I mean there's a lot of overlap,
Speaker 1: of course, but UM beam bridges tend to be the shortest,
Speaker 1: followed by arch bridges and then suspension bridges, and I
Speaker 1: think those UM the cable stayed bridge is is kind
Speaker 1: of a suspension bridge, so that counts. It's like a
Speaker 1: kind of a variation that can be very long as well. Yeah,
Speaker 1: not quite as long as suspension bridges, though from what
Speaker 1: I understand and this um, the suspension bridge affords the
Speaker 1: longest span. Okay, so you've got a big long span,
Speaker 1: it's it's suspension time. And they're also super expensive. Yeah,
Speaker 1: suspension bridges because all the bridge builders know that you've
Speaker 1: got a long span that you're trying to cross, you
Speaker 1: probably got some deep pockets and they're gonna milk you
Speaker 1: for it. Oh yeah, every penny. Yeah yeah, Like you
Speaker 1: need a suspension bridge, I'm your guy. Yep. Um. All right,
Speaker 1: so let's talk about there are a lot of different
Speaker 1: forces that can act on a bridge to make it
Speaker 1: not as stable. UM will cover a few of the
Speaker 1: other ones later, but the main two here early on
Speaker 1: our tension and compression. And the very easy way to
Speaker 1: think about these two things is tension is like if
Speaker 1: you if you and I are pulling a rope, like
Speaker 1: you're on one end and I'm on the other, We're
Speaker 1: gonna pull that sucker tight and I'm gonna fall over
Speaker 1: due to your massive strength. I'm pretty huge, But there
Speaker 1: will be some tension in that rope. Yeah, is f
Speaker 1: do you fall down? Yeah, and I'd start laughing. There
Speaker 1: would be tension, sure, But tension is the lengthening of something. Yes,
Speaker 1: Compression is the shortening of something, Yeah, like a spring collapse. Right.
Speaker 1: So it's easy to visualize when you're talking like springs
Speaker 1: and ropes and that kind of thing. But if you're
Speaker 1: talking about just a single deck of a bridge, which
Speaker 1: you think of as one piece, Um, it's tough too.
Speaker 1: It starts to get tough to visualize it until you
Speaker 1: realize that you have to look at like a bridge
Speaker 1: deck like the roadway on the bridge, as really having
Speaker 1: a top and a bottom. Yes, and forces, Well, the
Speaker 1: compression acts in the downward motion on the top, and
Speaker 1: the tension acts from the underneath coming up on the bottom. Right,
Speaker 1: So the bottom of the bridge, underneath it of the
Speaker 1: deck is going to be spread out under the force
Speaker 1: of tension. We're on top where it's being pushed down compressed.
Speaker 1: That's compression. Yeah, And they kind of, in a weird way,
Speaker 1: work together. Even though they're sort of opposite things, they're
Speaker 1: definitely related. Uh, And what will happen is if these uh,
Speaker 1: if you aren't a very good bridge builder, um, buckling
Speaker 1: will occur when it's compressed on the top, and snapping
Speaker 1: can occur on the bottom when tension is at work.
Speaker 1: That's right, all sounds very can using. But if you
Speaker 1: just I gotta do is like put your hand out
Speaker 1: and look at it, right, you know, and so or
Speaker 1: if you take and push down on your hand or
Speaker 1: on your hand, right, you know what I'm saying like that, yeah,
Speaker 1: like that. Um, the whole thing becomes very very evident
Speaker 1: when you look at a beam bridge, right, the most
Speaker 1: basic form of a bridge, like if you dropped a
Speaker 1: log over a river, right, and this this thing. Um.
Speaker 1: This article used the example of like taking a pair
Speaker 1: of milk crates and putting like a two by four
Speaker 1: across them. Right, if you put like a bowling ball
Speaker 1: on a bowling ball stand so it doesn't roll around
Speaker 1: on top of the um on top of or right
Speaker 1: in the middle of your two by four, which makes
Speaker 1: up your beam bridge deck. Right, Um, you're gonna see
Speaker 1: that it bows. And what you're seeing is that on
Speaker 1: the top it's being compressed. On the bottom, it's being
Speaker 1: um tensed. Right. Um, And what you've just done is
Speaker 1: at a low to that bridge. And there's two kinds
Speaker 1: of loads to start out with. There's a deadload, which
Speaker 1: is the weight of the bridge and all of its
Speaker 1: materials combined. And then there's a live load, which is say,
Speaker 1: like the cars and the people and the trains and
Speaker 1: everything that that add the extra weight while they're moving
Speaker 1: across it and everything. And as you add this extra load,
Speaker 1: first of all, the bridge is already dealing with its deadload.
Speaker 1: It's got to hold that up. That's job number one
Speaker 1: for a bridge. Yeah, Like if you had a three
Speaker 1: hundred foot two by four and two milk crates is
Speaker 1: gonna sag in the middle just naturally, right, and it
Speaker 1: might even break. And there have been bridges that have
Speaker 1: been built that where the guy forgot to carry the
Speaker 1: one or whatever and they couldn't stand up under their
Speaker 1: own weight and they collapse from their own weight. They
Speaker 1: collapse from the deadload. So job number one of the
Speaker 1: bridge is to support its own weight. Job number one
Speaker 1: point one is to support all of the live load
Speaker 1: the traffic that goes across it as well. Uh. And
Speaker 1: the two ways that you're going to do this to counteract.
Speaker 1: Tension and compression are dissipation and transference force or transferring
Speaker 1: the force. So with dissipation you spread out that force equally,
Speaker 1: you spread out over a wide area, and with transferring um,
Speaker 1: you move the area of weakness to an area of strength, right,
Speaker 1: which pretty simple. Yeah, they're kind of tough to distinguish sometimes, Yeah,
Speaker 1: you know what I mean. But for example, like the
Speaker 1: best example of dissipation is the arch, which we'll talk
Speaker 1: about how that works in a second. Yea, um, but
Speaker 1: suspension bridges are best at transferring the um the tension
Speaker 1: and compression forces. That's right. So if you're if you're
Speaker 1: talking about a beam bridge, that most basic kind. Uh.
Speaker 1: The other thing they're gonna do to make it stronger,
Speaker 1: of course is use back in the old days to
Speaker 1: use wood than later iron and then steel, maybe some
Speaker 1: concrete mixed in um. But the size of the beam
Speaker 1: is going to be really important. Like the height of
Speaker 1: the beam is important because the the top is gonna
Speaker 1: experience stress, the bottom is gonna experience stress in the
Speaker 1: middle not as much. So a good I beam, a
Speaker 1: good tall I beam, is what you want. Yeah, and
Speaker 1: I didn't realize that that's why I beams are made
Speaker 1: like I beam, the center of like the deck or
Speaker 1: the beam or whatever. Any kind of beam is going
Speaker 1: to experience the least amount of compression or tension. It's
Speaker 1: really the top or the bottom. So you don't have
Speaker 1: to put quite as much material into the center of
Speaker 1: the beam as you do the top and the bottom
Speaker 1: to prevent buckling and snapping. That's right. So the beam bridge,
Speaker 1: you're gonna add what's called a truss uh to make
Speaker 1: it stronger. This we'll talk about trust is more but
Speaker 1: it's basically triangulated strength. And you'll see a trust if
Speaker 1: you've ever seen like a a train bridge, like you
Speaker 1: see a truss on top, or like in areas where
Speaker 1: they get a lot of snow, roof supports will frequently
Speaker 1: be trusses. Yeah, and that's a three trust on top
Speaker 1: we already said. And if it's underneath then it is
Speaker 1: uh the deck trust. And you can have both, but usually,
Speaker 1: like with the railroads, you'll see like that top trust
Speaker 1: not the same as a trestle. That's different. It's like
Speaker 1: like a roller coaster, you know. So after this break,
Speaker 1: why don't we talk more about trust bridges? Nice? So, Chuck,
Speaker 1: no joke, trusses are one of my favorite things. Now
Speaker 1: it's pretty neat. After doing some research into them, I'm like,
Speaker 1: I love trust is your trust guy? Yeah? And it's
Speaker 1: because they're so elegant and simple. They're elegantly simple basically.
Speaker 1: So um. I saw this really great explanation where it
Speaker 1: was on Make magazine, and I think it was called like,
Speaker 1: ask Make, how do trust his work? Pretty straightforward? Um,
Speaker 1: And it basically had like a really get a great
Speaker 1: graphic of taking using popsicle sticks. Right, Let's say you
Speaker 1: make a square out of popsicle sticks and you join
Speaker 1: the popsicle sticks together at the corners where the ends
Speaker 1: all meet. Yeah, a little Elmer's paste maybe makes sense,
Speaker 1: seems pretty supportive. Right, But when you pressed down on
Speaker 1: any one of those joints, which is where the load's
Speaker 1: going to be centered or distributed most remember the ends
Speaker 1: the square shift to the side, and all of a
Speaker 1: sudden you have a rhombus. Well, rambus is inherently less
Speaker 1: structurally sound than square, which is why you very rarely
Speaker 1: see rambus as in architecture. Right, with a triangle, when
Speaker 1: you press down at any one of the joints it
Speaker 1: distributes that can pression or tension directly through the center
Speaker 1: of the beam, so the triangle stays totally rigid. And
Speaker 1: when you add, the more triangles you add, the more
Speaker 1: support you have. So they're like basically like as far
Speaker 1: as the shape goes, the superconductor of transferring or distributing
Speaker 1: compression or tension. Yeah, that's a good way to put it.
Speaker 1: And that's why when you see that that train tress
Speaker 1: alone that has that trust on top, it's got all
Speaker 1: those beautiful diagonal uh pieces of metal and it's not
Speaker 1: just for for looks, even though it is cool looking. Now,
Speaker 1: one of the other great things about a trust is
Speaker 1: that there you know, it's like just a three steel
Speaker 1: beams or three whatever aluminum beams. They're just three pieces
Speaker 1: of metal, usually fixed together. And that's that's the other
Speaker 1: key that I left out. They have to be connected
Speaker 1: at the ends equally distributed from each end. Right, So
Speaker 1: let's say you you drill a hole to to rivet
Speaker 1: one side of the trust to another, or one end
Speaker 1: of the trust to another end, the the other end
Speaker 1: has to be equally far away, right. Do you see
Speaker 1: what I'm saying? Yeah, yeah, okay. They wouldn't just be
Speaker 1: like just droll that other one wherever. So anyway you
Speaker 1: have to the place where the trust sides join together
Speaker 1: has to be on the ends and then but one
Speaker 1: of the things that it allows for is for wind
Speaker 1: to blow through it easily. That's a huge point about trusses.
Speaker 1: They're not solid in that they don't they don't put
Speaker 1: up a lot of resistance to when they allow it
Speaker 1: to flow through, which is really kind of what you want.
Speaker 1: We'll see when you're building bridges. Yeah. I think even
Speaker 1: the covered bridges have is more of a lattice type
Speaker 1: thing on the sides. Right, Yes, it's not solid, is it.
Speaker 1: That'd be dumb a covered bridge. Yeah, yeah, they're solid.
Speaker 1: I thought the walls were usually like a lattice so
Speaker 1: wind could pass through. Now and they had that had
Speaker 1: a roof and like a lattice e side is the right. Yeah,
Speaker 1: maybe there's all kinds. I think those are just to
Speaker 1: keep the rain off. Oh yeah, that's what you said
Speaker 1: earlier and keep shooting down the theoris structure. Yeah. But anyway,
Speaker 1: trust is rock, I guess, is what I'm trying to say. Yes,
Speaker 1: there's your T shirt. Trust is rock. So are we
Speaker 1: at arches? Do we say that they frequently used trusses
Speaker 1: to support beam bridges. Yeah, arches. Now, when we say
Speaker 1: a bridge is an arch bridge, the deck is not
Speaker 1: some big hill that you drive over. The deck is
Speaker 1: flat the arches underneath. Uh right, yeah. And you can
Speaker 1: have a single arch if your span isn't it long,
Speaker 1: or you can have a big one with like six
Speaker 1: or eight arches. Although I've seen I think there are
Speaker 1: like short arch bridges that actually do go up and down,
Speaker 1: you know, like if I mean there's natural arch bridges
Speaker 1: like rock form a sans like that, and that's why
Speaker 1: they're still standing. There's um there's there's a bridge that
Speaker 1: forms like a perfect circle. So like when when you
Speaker 1: see it reflected in the water, it just looks like
Speaker 1: a circle. Arch bridges are pretty cool too. There are
Speaker 1: no trusses, but they're beautiful in their own way. That's true.
Speaker 1: Uh So the arches obviously semi circular um and like
Speaker 1: you said, if it meets the water and reflects nicely
Speaker 1: fully circular, fully circular, uh and the entire form is
Speaker 1: gonna divert weight onto what are called abutments, and this
Speaker 1: is what takes on the pressure. It's like I mean,
Speaker 1: if it's just a single arch. Those abutments are probably
Speaker 1: going to be part of the earth on one side
Speaker 1: or the other. Yeah. Um. And the whole point of
Speaker 1: an abutment is when you press down in an arch,
Speaker 1: or when you know, gravity pushes down on it or
Speaker 1: it's compressed, that force goes downward and it makes the
Speaker 1: sides of the arch go out out. Those abutments press inward,
Speaker 1: so that the force of compression just goes straight down
Speaker 1: through the arch circle the semicircle and into the earth
Speaker 1: or into the ground or whatever. Yeah. And and it's
Speaker 1: the arch. The what I thought was interesting, it's really
Speaker 1: all about fighting that compression. There isn't a lot of
Speaker 1: tension that comes into play with an arch bridge. I
Speaker 1: think the tension is grows more and more possible when
Speaker 1: the degree of the arc or arch grows. Okay, yeah,
Speaker 1: so that could come into play. It can, But for
Speaker 1: the most part, when you're building an arch, you have
Speaker 1: to worry about compression more than tension, gotcha. So there's
Speaker 1: a stylistically and artistically design wise. They're all kinds of arches,
Speaker 1: Baroque arches, Renaissance arches, Roman arches. They were the Romans
Speaker 1: built you know arch bridges that are still standing today. Um.
Speaker 1: Have you been to Rome? Yeah? Man, it's just like
Speaker 1: you're walking along and all of a sudden you look
Speaker 1: to your left and there's like a two thousand year
Speaker 1: old aqueduct, you know, hundred year old arch just sitting there. Yeah.
Speaker 1: I remember the first time I went to Europe coming
Speaker 1: back and being sort of like bummed out, you know,
Speaker 1: because we're walking along and then there's a burger king.
Speaker 1: You know, this house is two hundred years old. She
Speaker 1: could Rome. I know, my house is like eighty years old,
Speaker 1: and it seems super old. Nothing by Roman standards. No,
Speaker 1: but you know, a little drafty in those thousand year
Speaker 1: old apartments. Yeah. But it's so neat though, because I mean,
Speaker 1: like there's so much old surviving stuff that not all
Speaker 1: of it's even meant to be preserved. Some of it's
Speaker 1: just like just there. It's not like a part of
Speaker 1: a park or an historic exhibit. It's just part of
Speaker 1: the city. Yeah. You know. Yeah, I've heard other tours
Speaker 1: complaining about how dirty Romans and I'm always just like,
Speaker 1: come on, it's like focusing on the wrong part. It's
Speaker 1: been around for a long time time. Um. Oh yeah, yeah,
Speaker 1: and also, yeah, don't be stupid and just look around
Speaker 1: you like they're complaining in front of a two thousand
Speaker 1: year old fountain. I didn't notice that was particularly dirty.
Speaker 1: I mean, it wasn't any more dirty than like New
Speaker 1: York or anything any other big city. But the thing
Speaker 1: with the arch though, very stable once you get it built.
Speaker 1: But the building process it's tricky because until you connect
Speaker 1: those two ends, um, that's what gives it its strength.
Speaker 1: So until that happens, it's a little dicey. Yeah. Oh yeah,
Speaker 1: I had some scaffolding going fine. Yeah, And they used
Speaker 1: to build wood scalf scaffolds and supports to hold the
Speaker 1: thing and then you just would build it in um.
Speaker 1: Now they used suspension cables, like I think the biggest
Speaker 1: arch bridge on the planet is West Virginia's New River
Speaker 1: Gorge Bridge, and that thing is unbelievable. It really is.
Speaker 1: And what's cool is when you look at it, um,
Speaker 1: it just it uses the clip falls or the walls
Speaker 1: of the gorge as the abutments. Beautiful stuff, super strong.
Speaker 1: And that's where we're going to talk about that in
Speaker 1: our base Jumping. I know that's the fact that ties
Speaker 1: these two podcasts together. It's where they have bridge day
Speaker 1: talk about elegantly simple. So suspension bridges, for my money,
Speaker 1: are where it's at. I think they deserve their own
Speaker 1: um episode. Oh yeah, pretty, I'm pretty much they're they're
Speaker 1: that complex. Like this is just the briefest overview of
Speaker 1: bridges in general, but especially with suspension bridges. It feels
Speaker 1: like there's just so much going on with those things. Yeah,
Speaker 1: I agree. I mean ken Burns did like an eight
Speaker 1: hour long documentary on the Brooklyn Bridge alone. Yeah, that's true.
Speaker 1: He's a deep diver. We're over of you guys with
Speaker 1: a giant helmet to go over his giant haircuts a
Speaker 1: pretty big hair do. Um. Alright, So suspension bridges we mentioned,
Speaker 1: of course olden Gate Bridge and the Brooklyn Bridge. This
Speaker 1: is when you have your deck, your roadway is suspended
Speaker 1: by cables between can be a number of them, but
Speaker 1: uh to at least two tall towers that are supporting
Speaker 1: all of this weight and compression is pushing down, traveling
Speaker 1: up through those cables, and its transferring all that compression
Speaker 1: through all those lovely cables. Right. So, I mean another
Speaker 1: way to look at it is exactly what it sounds like.
Speaker 1: It's the bridge is suspended from cables, right, But if
Speaker 1: you really start looking into what it's doing, it's not
Speaker 1: just holding these things up. What's what's going on is
Speaker 1: there's a transfer of that natural compression of the deck
Speaker 1: up through the lines up, through the cables up down
Speaker 1: up to the towers, which, like you said, send them
Speaker 1: down to the earth. Right. So the towers that hold
Speaker 1: the bridge up are at the same time distributing or
Speaker 1: dissipating the forces of compression that are trying to hold
Speaker 1: the bridge down into the water below it. Yes, and
Speaker 1: the tension you also have to deal with as well,
Speaker 1: and apparently you deal with that using another part of
Speaker 1: the structure of suspension bridges, which are called anchorages. Yeah.
Speaker 1: Now that's just what the towers connected to at the
Speaker 1: base right now. No, huh So it's like, um, the
Speaker 1: anchorages is like the abutment essentially, Yes, yeah, yeah, they're
Speaker 1: left and right, they're like a suspension bridges abutments. Whereas
Speaker 1: as you get closer to the middle of the bridges,
Speaker 1: that's where the towers are. But on the very ends,
Speaker 1: like say where the roadway hits the bridge, you're gonna
Speaker 1: have a massive piece of rock or massive piece of
Speaker 1: concrete and those are the anchorages. And you have horizontal
Speaker 1: cables that distribute the compression from the bottom of the
Speaker 1: bridge to um the anchorages and those those transfer those
Speaker 1: into the earth. Yeah. And you might also, depending on
Speaker 1: the size of your suspension bridge, have to have that
Speaker 1: below deck us as well to help stiffen the deck um.
Speaker 1: And you know, if you're a four thousand foot bridge,
Speaker 1: you're gonna have all all kinds of trusses and decks
Speaker 1: and cables. And I think I finally figured out what
Speaker 1: it is about bridges that I love is that the
Speaker 1: the arc, the structural design that it needs to be strong,
Speaker 1: also happens to be beautiful. Yeah, you know what I mean,
Speaker 1: Like the way the cables are arranged. It's not like
Speaker 1: they're like, oh, this looks great. It's like, well, it
Speaker 1: has to be like this, but it also happens to
Speaker 1: be very striking like Grace Jones, you know what I mean? Yeah,
Speaker 1: absolutely so. Um So suspension bridges are your favorite, huh.
Speaker 1: I like him because there's so much going on, Like
Speaker 1: trust is, because they're so elegantly simple and they're just
Speaker 1: tough as nails. There's a bridge for everyone. I think
Speaker 1: there is um the cable stayed bridge, and we should
Speaker 1: say that suspension bridges. When you think of a suspension bridge,
Speaker 1: probably probably think of the Golden gate Bridge or something
Speaker 1: like that, right, Just a classic suspension bridge two towers
Speaker 1: to um anchorages, lets of suspension cables. It's a suspension
Speaker 1: bridge and you think, well, then they're probably pretty new. Wrong.
Speaker 1: Suspension bridges have been found in various forms for hundreds
Speaker 1: of years at least, and apparently the INCA were um
Speaker 1: masters at building rope suspension bridges out of woven grass.
Speaker 1: Crazy man, Yeah, hundreds they've discovered. The Spanish concut sators
Speaker 1: stumbled upon these were like, what in the world is
Speaker 1: going on here? Because the smart Europeans didn't figure this
Speaker 1: out for another like few hundred years after that. That's right, Um,
Speaker 1: the INCA is still have one of these bridges intact.
Speaker 1: It's it spans ninety ft um and they remake it
Speaker 1: every year as part of a three day festival. So
Speaker 1: really nice, which is why it's still attact because the
Speaker 1: grass woven grass rope bridge didn't last all that long necessarily,
Speaker 1: even though why when it's fresh and new, it's strong. Yeah,
Speaker 1: as an expiration date what you're saying. But apparently, as
Speaker 1: we'll learn, all bridges have an expiration date. All right,
Speaker 1: Well we'll take a break then with that tease and
Speaker 1: talk about the cable stayed bridge and then um, how
Speaker 1: you might die on a bridge one day. Alright, so
Speaker 1: we're onto your favorite, my friend, the super sleek, modern
Speaker 1: looking cable stayed bridge, which is actually actually actually has
Speaker 1: been around since like World War two. Yeah, but the idea,
Speaker 1: which is still modern. The idea came from a dude
Speaker 1: named um Fast Ranchic, yeah man, and he was a
Speaker 1: contemporary of Kepler and Brahi Um and he basically came
Speaker 1: up with the first design for a cable stayed bridge
Speaker 1: back in the sixteenth century. So what's what's the nuts
Speaker 1: and bolts of this thing? So basically it is a
Speaker 1: rather than two towers like a suspension bridge uses, a
Speaker 1: cable state bridge uses one tower. Well not always, um,
Speaker 1: there's plenty of them that have more than one, but okay,
Speaker 1: but for a particular span of bridge, there's one tower
Speaker 1: supporting that one span, right, Um, So it's basically you
Speaker 1: can't use it for as long of a span as
Speaker 1: a suspension bridge. But if you have a slightly shorter span,
Speaker 1: and you don't want to spend quite as much money,
Speaker 1: and you don't want as many wires up there and everything.
Speaker 1: You can go with a cable stay bridge. So you
Speaker 1: have one usually one UM tower holding up all the cables,
Speaker 1: and the cables can either all connect to one point
Speaker 1: which is called a UM radio pad. Right, So it's
Speaker 1: like all these different cables are connecting on the bridge
Speaker 1: deck at different points, but they're all connecting at about
Speaker 1: a single point on the tower. Again architecturally lovely, very
Speaker 1: neat looking. And then another way that you can do
Speaker 1: it is UM in a parallel pattern, so they're connected
Speaker 1: at different points on the deck and they connect at
Speaker 1: different points on the tower. And that's the case with
Speaker 1: the Erasmus Bridge, which I think is the most beautiful
Speaker 1: bridge in the World's in Holland. Well that doesn't surprise me.
Speaker 1: I mean, look at that thing. Look at that pal
Speaker 1: Oh yeah, that's something else. Yeah, I wish you guys
Speaker 1: could see this. Well they can look at up. It
Speaker 1: doesn't look like very Dutch though, No, it looks very um.
Speaker 1: It's like the New Holland, I guess, yeah, new Amsterdam.
Speaker 1: I'm just picturing like Holland. I think of uh you know,
Speaker 1: wooden windmills and like tulips and stuff like that. Sure, yeah,
Speaker 1: this is modern halland for it looks like something that
Speaker 1: would be in like Sydney, Australia. Well they have great
Speaker 1: bridge to they do. Maybe that's what I'm thinking, um,
Speaker 1: living bridge, Well you are you done with those? Well
Speaker 1: I was gonna say another design for cable state bridge
Speaker 1: looks a lot like a sailboat with them the tower
Speaker 1: standing straight up and then on each side cables going
Speaker 1: down at a diagonal from it to make it look
Speaker 1: like a sailboat, sail and masked and again for structural
Speaker 1: integrity more than anything, right, um living bridges. Sure, Uh,
Speaker 1: well I guess we should say cable state bridges are
Speaker 1: uh they can't be as long as suspension bridges, but
Speaker 1: they can be pretty long. Yeah, like up to close
Speaker 1: to three thousand feet. But that's what I'm saying, Like,
Speaker 1: if you have a shorter span and you don't want
Speaker 1: to use as many materials enhance you spend as much money,
Speaker 1: a cable state bridge is a great alternative. Yeah. I
Speaker 1: wonder when cities, Uh, I wonder what the considerations are, um,
Speaker 1: like money what you. I would guess money first and
Speaker 1: foremost money, what you probably is best for the land.
Speaker 1: And but I also bet that that architecture comes into play,
Speaker 1: like how it looks in the city escape, But don't
Speaker 1: you think like it. Usually a city will have some
Speaker 1: sort of well accept several designs, competing designs, and then
Speaker 1: probably well, like in Atlanta's case with the seventeenth Street bridge,
Speaker 1: goes with the cheapest one and then half of it
Speaker 1: falls down on the traffic later, like a couple of
Speaker 1: years later. Did that happen? Yeah? Uh, when um, like
Speaker 1: to two years ago? Really? Yeah, man, it was a
Speaker 1: big deal. Luckily it happened at like four in the
Speaker 1: morning or five in the morning. But like when you're
Speaker 1: walking on the bridge, you know the side stuff, one
Speaker 1: whole side fell over onto onto the onto the connector
Speaker 1: right below. Yeah, I kind of remember that. Yeah, but
Speaker 1: it's an ugly bridge to begin with. Three allion dude,
Speaker 1: if you're listening, the guy who designed it, I'm sorry,
Speaker 1: I don't mean to insult your work, but I but
Speaker 1: do better. It just the city could have done better,
Speaker 1: I think. Yeah, But I think what it came down to,
Speaker 1: I'm sure it was all of these are beautiful, but
Speaker 1: we're just going to spend the money on this one,
Speaker 1: you know, or whoever got the biggest kick back or
Speaker 1: wherever that came from, not to be cynical living bridges. Yeah,
Speaker 1: we're talking about that. Um. If you go to northern
Speaker 1: India to the here we go, uh, the Meghalaya region,
Speaker 1: I think that was good. All right, close enough, Um,
Speaker 1: they have something pretty remarkable and they are called living bridges.
Speaker 1: And what they did was it's so rainy there that
Speaker 1: all of their natural bridges were having a hard time
Speaker 1: staying intact because of all the moisture from monsoon season. Yeah,
Speaker 1: and that's you know, you can't have a natural bridge
Speaker 1: with that much water. So they said, why don't we
Speaker 1: take these tree roots and grow them out of the
Speaker 1: ground and span a river over the course of years
Speaker 1: and years and years and then basically plant on the
Speaker 1: other side into the ground. And this is now a
Speaker 1: natural tree root bridge. Right. It's like giant living bonds.
Speaker 1: I like you're they were training routes to go a
Speaker 1: certain way, and they would take a um, a tree,
Speaker 1: a felled tree and split it in half and use
Speaker 1: that as the guide. Right, it's like the structure so
Speaker 1: that they were building an arch, but they weren't making
Speaker 1: an arch like sort of a temporary bridge exactly, and
Speaker 1: they let the roots grow along that and like they
Speaker 1: would plan these things out, or they do plan these
Speaker 1: things out over the course of like a decade. And
Speaker 1: I get the impression it's, um, the whole town's responsibilityly,
Speaker 1: some people in the town's responsibility to make sure that
Speaker 1: if you see your route starting and go down in
Speaker 1: the wrong place, you just suck it up and put
Speaker 1: it back on that fell log that's guiding it across
Speaker 1: the way. Yeah, it's pretty neat, like it requires patients obviously,
Speaker 1: but it also, um, I imagine just once a day
Speaker 1: someone walks down and it's like, yep, looking good, and
Speaker 1: then just walks away again. Pets. The bridge says, keep growing,
Speaker 1: walk across you in ten years, buddy. And apparently those
Speaker 1: things can last up to fifty years or the the
Speaker 1: largest one that they have up to a hundred feet,
Speaker 1: which is thirty meters for our friends in India. Um,
Speaker 1: and it can bear the way to fifty people and
Speaker 1: last up to five hundred years, not fifty. That's what
Speaker 1: I said. Oh, I thought you said fifty people. Well,
Speaker 1: it's crazy, like you got to google these things. Yeah,
Speaker 1: they're very pretty, very pretty. It looks very um dark crystally.
Speaker 1: Oh yeah, totally. You know what I mean. But they're
Speaker 1: not unsettling at all like the Dark Crystal, which, by
Speaker 1: the way, if you're ever in Atlanta, sometimes people say, Hey,
Speaker 1: I'm coming to Atlanta. What should I do? Uh, go
Speaker 1: to the Center for Popetry Arts and just look at
Speaker 1: their free exhibit, which includes a full size Skexy. It's terrifying. Yeah,
Speaker 1: they have We've talked about this before. They have emmett Otter.
Speaker 1: That's right for me. That was pretty pretty magnificent mental
Speaker 1: lot for emm and Otter to meet you too. They're
Speaker 1: doing Actually I saw it was just at the Museum
Speaker 1: of the Moving Image and Queens. Oh yeah, I saw
Speaker 1: you post something about that. Yeah, they have a Madman
Speaker 1: exhibit right now, which is pretty neat, but it was
Speaker 1: they I was not there in time for the Jim Henson.
Speaker 1: When they're they're putting that in place, I think for later.
Speaker 1: It's coming. It's coming. What's good You didn't miss it yet? Well, yeah,
Speaker 1: I'll just go back. We went to the Yoko on
Speaker 1: No exhibit at MoMA awesome. She's something else, dude. She's
Speaker 1: got a pretty cool mind. Yeah, she had she had
Speaker 1: this one display and it was titled three Spoons and
Speaker 1: it was just four spoons in a row. It wasn't three.
Speaker 1: I love that stuff, So I recommend that as well.
Speaker 1: I'm not a fan of her music, though I actually
Speaker 1: got turned onto her music in the listening room there
Speaker 1: Plastic Band. It's crazy, it's weird stuff, but I kind
Speaker 1: of like it. I mean, she's definitely one of the
Speaker 1: most like original thinkers you know out there, and she's
Speaker 1: been at it for a while, like a lot of
Speaker 1: the stuff went back to the sixties, like the early sixties. Yeah,
Speaker 1: and talk about weathering criticism and still just being like
Speaker 1: screw you. Yeah, I'm Yoko. Oh no, I don't care
Speaker 1: what you say. Well, she was exonerated to recently, remember
Speaker 1: Paul McCartney came out and said like, it was not
Speaker 1: Yoko owner that broke up the Beetles and saying that
Speaker 1: it just took him like fifty years to come out
Speaker 1: and see it. Yeah, you know, she's like, would it
Speaker 1: kill you? Right? You've told me privately many times, but
Speaker 1: we'll press release, tweet it alright. So we talked about
Speaker 1: compression and uh tension being the two main forces. Uh.
Speaker 1: There are quite a few other forces, dozens even that
Speaker 1: can act on a bridge in a negative way, And
Speaker 1: the scariest one, for my money, is torsion. Um. If
Speaker 1: you've ever seen the video, it's a very famous video
Speaker 1: of the bridge. What is it the Tacoma the Tacoma
Speaker 1: Narrows Bridge to Comma Narrows Bridge when it looks like
Speaker 1: a wet noodle twisting in the wind. Yeah, it was.
Speaker 1: It's nuts. And they have like footage of this whole
Speaker 1: thing just undergoing this destruction that kept just going on
Speaker 1: and on and on, and finally the bridges comes down. Yeah.
Speaker 1: The craziest part is when you're watching it, you just think, oh, man,
Speaker 1: look at that thing. It's nuts, and thank god there's
Speaker 1: no one on it. And then you see I con
Speaker 1: dude walking on it in a car. Yeah, and a
Speaker 1: guy ran. There was a dog. There's one car in there,
Speaker 1: and there's a dog trapped in the car and some
Speaker 1: guy ran and got the dog. Yes, pretty great heroic stuff. Sure.
Speaker 1: Then later on, I don't know if he's the same
Speaker 1: guy and another guy or just two completely new guys.
Speaker 1: They're just walking along it. This is after a whole
Speaker 1: section is falling into the river. But the section they're
Speaker 1: walking on is still swaying. But the only way from
Speaker 1: the bridge step back from the bridge, man, So that's
Speaker 1: torsion at work. Yeah, and that's a big problem that
Speaker 1: designers a suspension bridges face because you have a deck
Speaker 1: that's being held from being held alof by cables. Right,
Speaker 1: it's not like fixed to anything below. It necessarily mean
Speaker 1: it's being suspended. So just like on like a rope
Speaker 1: bridge or something like that, it sways very easily. Right. Yeah,
Speaker 1: those towers are strong, but it's not, you know, directly
Speaker 1: connected to those towers. So if you have a swaying
Speaker 1: bridge in between them, right, and the thing is swaying
Speaker 1: back and forth, but if one side starts to sway
Speaker 1: over the other side and all of a sudden, you
Speaker 1: have an opposing circular force, and that's torsion, and that
Speaker 1: can basically rip the bridge in into which is sheer. Yeah.
Speaker 1: Well that's the other awful thing that can happen. It
Speaker 1: can just snap, well not snap, I guess, but just
Speaker 1: breaking to two parts. Yeah. Well, I mean snapping is
Speaker 1: the result of compression shearing would be what it's called technically,
Speaker 1: where to the same span of bridge has the two
Speaker 1: opposing four is acting on it at once UM in
Speaker 1: opposite directions and it goes it makes that terrible sound. UM.
Speaker 1: If you want to combat torsion, UM many ways to
Speaker 1: do this, you're you're probably gonna have a deck trust
Speaker 1: going on to help out. Trust saves the day. That
Speaker 1: trust saves a day you're gonna have. You're gonna do
Speaker 1: wind tunnel tests if it's a modern bridge beforehand, well
Speaker 1: you're gonna make a model, yeah, and do tests and
Speaker 1: see like how does wind affect this bridge and what
Speaker 1: do we need to do. But the thing is with
Speaker 1: the um With the Tacoma Narrows Bridge in particular, they
Speaker 1: did tests. They had that thing rated with standing winds
Speaker 1: up to a hundred and twenty miles an hour, but
Speaker 1: the winds that day that brought it down, we're only
Speaker 1: forty miles an hour. And for a long time they
Speaker 1: were like, what happened, and somebody said, you know what
Speaker 1: it was? It was mechanical residents. It was. Yeah, the
Speaker 1: deck trust was not sufficient for the span that was
Speaker 1: part of it and the way that the wind hit it. Right,
Speaker 1: and the angle calls the final thing that he just
Speaker 1: mentioned resonance, which is um sort of. It's a vibration
Speaker 1: basically that gets out of hands. So resonance, to me,
Speaker 1: I think deserves its own podcast too. It's awesome. Everything
Speaker 1: every especially anything that we build, from an airplane to
Speaker 1: a bridge, to watch it has a certain frequency um
Speaker 1: where it will really pick up force, really absorbed force,
Speaker 1: it will run through it. Right, So let's say that
Speaker 1: your bridge um has a resonance Uh, that's like at
Speaker 1: a frequency of ten. That's probably a totally ridiculous number
Speaker 1: that I just said, But let's say it's tent right.
Speaker 1: And then let's say that wind comes at it at
Speaker 1: forty at just the right angle, and it makes it
Speaker 1: sway at a frequency of nine, Well, that bridge is
Speaker 1: gonna be It's just gonna sit there and sway. Not
Speaker 1: a big problem. If that wind hits it at just
Speaker 1: the right angle at just the right speed it's and
Speaker 1: it starts swaying at eleven, it's still not quite a problem.
Speaker 1: But if it gets it just right and it starts
Speaker 1: it swaying at ten, all of a sudden, those sways
Speaker 1: are going to become more and more pronounced, because all
Speaker 1: that energy is flowing through at its maximum potential and
Speaker 1: at its freest flow, because it's hitting the bridge at
Speaker 1: its natural resonance, right, And that's what caused the Tacoma
Speaker 1: Narrows Bridge to come down, because once that thing starts going,
Speaker 1: there's no coming back from it because it's just happening.
Speaker 1: It gets worse and worse, exactly, and that's that's because
Speaker 1: it hit it at just the right frequency. Yeah, they
Speaker 1: like in it in the article, which I think is
Speaker 1: pretty uh down to earth of a snowball rolling downhill exactly.
Speaker 1: It just keeps getting worse and worse and you can't
Speaker 1: stop it. So, but isn't that bizarre that you a
Speaker 1: bridge has a natural resonance and natural frequency. I don't
Speaker 1: think so. I like, I would assume it would vibrate. Yeah,
Speaker 1: it did not occurred to me at all. And I
Speaker 1: was talking to Adam about this too, and I was like,
Speaker 1: so I saw that building designers, bridge designers. They will
Speaker 1: fine tune like a structure so that it resonates at
Speaker 1: a frequency that it's probably never gonna encounter from an
Speaker 1: earthquake or from winds or whatever. I'm like, how do
Speaker 1: you do that. And apparently it comes down to the
Speaker 1: building materials you use, the shapes you use to form
Speaker 1: the structure, the way you join those shapes together. And
Speaker 1: you can basically say, I'm giving this building a frequency
Speaker 1: of one point five, whereas I know all of the
Speaker 1: wind in the area and the ground movement from an
Speaker 1: earthquake is going to make it vibrated a frequency of seven,
Speaker 1: so it'll be fine. Yeah. And one way, like you said,
Speaker 1: they can do that is by not having like one
Speaker 1: like shortening the sections of the deck, let's say, And
Speaker 1: that way the vibration when you have these overlapping plates
Speaker 1: and smaller sections, Uh, it's going to create enough friction
Speaker 1: to disrupt that frequency. Right, it'll change the frequency that
Speaker 1: the bridge is moving at. But I mean and not
Speaker 1: just bridges too. You have to take this and take
Speaker 1: into account like airplanes, right, you can't use engines on
Speaker 1: airplanes that create vibrations at a frequency that's at the
Speaker 1: natural residence of the airplane body. Whuls the airplane body
Speaker 1: is going to come apart just from turning the engines on.
Speaker 1: Could you imagine seeing the airplane wings starting to flap
Speaker 1: like harder and harder, Right, But apparently the more common
Speaker 1: thing when you have a disaster catastrophe from a resonance,
Speaker 1: a mechanical resonance problem. Um, it's like one bolt. It's
Speaker 1: like I can't take it anymore and stops, and then
Speaker 1: that leads to a cascade of failures that ultimately has
Speaker 1: the bridge coming down. Interesting. I think that's fascinating. I
Speaker 1: had no idea that you had to worry about frequencies
Speaker 1: and vibrations. Why all the bridges you've built of collapse?
Speaker 1: They collapse pretty easy. Well, if you've ever heard the
Speaker 1: old they go down like a French boxer. That means
Speaker 1: I don't need um. But it was a glass Joe reference.
Speaker 1: Remember him from Tyson's punch Out, Oh No counter. He
Speaker 1: says he was French. Glass Joe said, a glass jaw,
Speaker 1: and he went down just like a sack of potato.
Speaker 1: So easy, man, Well, which was it a sack of
Speaker 1: potatoes or a French boxer? He was both. He went
Speaker 1: down like a sack of French potatoes. Yes, French fries.
Speaker 1: My bridges go down like a French boxer. But Glass Joe,
Speaker 1: the French boxer went down like a sack of potatoes. Ergo,
Speaker 1: my bridges go down like a sack of potatoes. Um,
Speaker 1: if you've ever heard the old wives tale that like
Speaker 1: an army marching across the bridge and step can cause
Speaker 1: enough vibration to take down that bridge, it's true that
Speaker 1: could happen. So if at the right frequency, right yeah,
Speaker 1: and wartime, that's they will break step. In other words,
Speaker 1: their rhythm isn't all the same to avoid that scenario.
Speaker 1: And there was a bridge disaster I saw on that
Speaker 1: Time magazine slide show where that happened. Um, there were
Speaker 1: there were a pair of skywalk bridges inside the Higher
Speaker 1: Regency Kansas City Hotel. Um in the lobby. They were
Speaker 1: just like you know, raised bridges going through the lobby,
Speaker 1: and they collapsed in and killed like a bunch of
Speaker 1: people because thirty something people people marching dancing. They were
Speaker 1: dancing on the on the skywalk. And you think, like
Speaker 1: up to today or yesterday when I started researching this,
Speaker 1: right like, I just thought that's weight or pressure something
Speaker 1: like if everybody's dancing, it didn't. It never occurred to
Speaker 1: me that the rhythm had something to do. I had
Speaker 1: always heard that, well, you're far more advanced than I
Speaker 1: am in structural engineering. My friend, Now that it's just
Speaker 1: always heard that, like, you know, even a bunch of
Speaker 1: kittens walking across could cause that. And the reason they
Speaker 1: said kittens of course, so it has nothing to do
Speaker 1: with weight, right, because kittens knowing nothing. And consequently, I
Speaker 1: think Lina Richie had to change the name of that
Speaker 1: song because of the accident. I think originally it was
Speaker 1: what a feeling when you're dancing on the skywalk and
Speaker 1: he had to change it to ceiling and everyone's like,
Speaker 1: that's weird, held dance on the ceiling, but it rhymes
Speaker 1: and he's like, yeah, but nobody ever died from dancing
Speaker 1: on this on the ceiling. I guess the final thing
Speaker 1: we should mention is that weather um obviously will play
Speaker 1: a big impact. We already talked about wind, but um
Speaker 1: over the years, the materials they use and the design
Speaker 1: is gone in to take account things like wind and
Speaker 1: uh what sun damage. I don't know what. I think
Speaker 1: the Freese thaw cycle is huge. Salt salt exposure if
Speaker 1: it's going over like a salty body of water. Yeah,
Speaker 1: that makes sense. Yeah, there's a lot of things that
Speaker 1: are trying to bring a bridge down. Nature abhores a
Speaker 1: bridge basically as much as a vacuum. Um, I've got one.
Speaker 1: What you got? There's probably around six hundred and thirty
Speaker 1: thousand bridges in the US alone, because there were six
Speaker 1: hundred and seventeen thousand, nine hundred and thirty five and
Speaker 1: a two thousand two census, and they add them. They
Speaker 1: were adding them at about a thousand a year, maybe
Speaker 1: nine hundred a year. That's just the US. The world's
Speaker 1: longest bridge completed in two thousand and ten, the Danyang
Speaker 1: Coon Shawn Bridge. I think I've seen pictures of that.
Speaker 1: It serves as a railway bridge for the Beijing and
Speaker 1: Shanghai railway. It's a hundred and two mile long bridge.
Speaker 1: That's nutty over water. I'm a big fan of of
Speaker 1: cities with multiple water bridges. Well, that's why you liked
Speaker 1: Pittsburgh and Pittsburgh, Portland, Budapest. I'm a big fan Atlanta.
Speaker 1: Doesn't mean we have bridges, but it's not like you
Speaker 1: have to go to the Chattahoochee River Lakes. Nobody goes
Speaker 1: to the Chattahoochie You know what, Um, I got One
Speaker 1: more thing I want to shout out to PBS is
Speaker 1: build it big website, which is like beyond nineties as
Speaker 1: far as websites go. But it was extremely helpful and
Speaker 1: understanding the forces that work on bridges, different types of bridges,
Speaker 1: different specific bridges. Great website and thanks to Adam. I
Speaker 1: guess you got some information from him. Yeah, thanks Adam.
Speaker 1: Was he into talking to you about it or was
Speaker 1: he on the other end going, oh my god, just
Speaker 1: shut up, I'm watching Tim and Eric he was he
Speaker 1: was into talking about it. I figured he would be. Yeah. Uh.
Speaker 1: And I actually have to shout out to you me too,
Speaker 1: because I told her we were building bridges or well,
Speaker 1: that we were talking about bridges. She sent me a
Speaker 1: bunch of stuff on popsicle bridges. Um, apparently there's a
Speaker 1: a Indie go go for the world's strongest or Canada's
Speaker 1: strongest popsicle bridge. Yeah, they're trying to build that. Yes,
Speaker 1: and they have like six grand already, man for out
Speaker 1: of popsicle sticks. Good for them. So that's everybody getting
Speaker 1: shouted out to all all over the place in this one. Huh.
Speaker 1: That's nice stuff, bam. If you want to know more
Speaker 1: about bridges, you can type that word into the search
Speaker 1: bar at how stuff works dot com. And since I
Speaker 1: said search parts time for listener, mayl I'm gonna call this,
Speaker 1: I get a couple of street gang responses, will read
Speaker 1: over the next couple of shows. Um, here's one. I
Speaker 1: had to write in about your street gangs episode as
Speaker 1: it was interesting and pertains to my job. Short version
Speaker 1: is that I worked for a hospital based program and
Speaker 1: we see every gunshot wound victim and stab wound victim
Speaker 1: who comes through, which is about four year UM, and
Speaker 1: about ten percent of those are gang involved. How you
Speaker 1: guys have mentioned how you found the number of gangs
Speaker 1: to be hard to believe, but I think you may
Speaker 1: be thinking of street gangs is one entity that has
Speaker 1: strict borders and lots of people. Uh, And my experience,
Speaker 1: larger gangs will sometimes incorporate smaller gangs, and sometimes larger
Speaker 1: gangs will split off into many many smaller groups. UH.
Speaker 1: People go in and out of gangs and are sometimes
Speaker 1: affiliated with more than one. Currently, we have about at
Speaker 1: least seventy in our city alone, on a substantial amount
Speaker 1: of those have less than twenty members, so like mini gangs,
Speaker 1: not super gangs, not super ganks. According to this paper
Speaker 1: on street gangs in Boston, of the gangs in the
Speaker 1: city have less than ten members and have ten to
Speaker 1: nineteen members. So while the numbers you gave seem shockingly high,
Speaker 1: they also seem to be in step with the current climate.
Speaker 1: And that is from Arianna. And what city did she say?
Speaker 1: You know, I don't see that. I don't think she said.
Speaker 1: I don't know if it was Boston or if she
Speaker 1: just referenced Boston. Well, thanks a lot, Ariana. We appreciate
Speaker 1: that email. And yeah, keep them coming. We wanted them
Speaker 1: more about gangs. I just had the impression the whole
Speaker 1: time that like one way or another, we were officially
Speaker 1: or unofficially misinformed. We maybe uh. And also let us
Speaker 1: know who's the coolest famous person you've ever met? Uh.
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