Suspension Bridges of Disbelief
November 19, 2015 5:56 PM Subscribe
Movies often portray suspension bridges being destroyed (for example) but often make basic mistakes that reveal a lack of understanding of how these structures work. This article by structural engineer Alex Weinberg, P.E. aims to fix this.
Mine, too, Dysk! My oldest kid and I watched a Great Courses class on structures a couple of years, so I understood this really well. So cool.
"Nolan, who famously hired astrophysicist Kip Thorne to advise him on black holes for Interstellar, failed to hire a sophomore engineering student to explain regular gravity here on Earth."
"However, in the film world, bridge suspension cables are purely decorative elements that can be destroyed without consequence. "
posted by not that girl at 6:20 PM on November 19, 2015 [6 favorites]
"Nolan, who famously hired astrophysicist Kip Thorne to advise him on black holes for Interstellar, failed to hire a sophomore engineering student to explain regular gravity here on Earth."
"However, in the film world, bridge suspension cables are purely decorative elements that can be destroyed without consequence. "
posted by not that girl at 6:20 PM on November 19, 2015 [6 favorites]
My oldest kid and I watched a Great Courses class on structures a couple of years
YES! Those lectures are terrific.
"However, in all of the planning, storyboarding, rendering, and compositing of these special effects shots, nobody pauses to consider how suspension bridges actually behave. I can accept messianic alien orphan superheroes and skyscraper-sized battle robots, but I will not stand for inaccurate portrayals of structural mechanics." Great stuff; thanks, AndrewStephens!
posted by MonkeyToes at 6:24 PM on November 19, 2015 [7 favorites]
YES! Those lectures are terrific.
"However, in all of the planning, storyboarding, rendering, and compositing of these special effects shots, nobody pauses to consider how suspension bridges actually behave. I can accept messianic alien orphan superheroes and skyscraper-sized battle robots, but I will not stand for inaccurate portrayals of structural mechanics." Great stuff; thanks, AndrewStephens!
posted by MonkeyToes at 6:24 PM on November 19, 2015 [7 favorites]
"These main cables will form a parabola"
Not a catenary?
posted by ctmf at 6:28 PM on November 19, 2015 [4 favorites]
Not a catenary?
posted by ctmf at 6:28 PM on November 19, 2015 [4 favorites]
A catenary curve is formed by a cable hanging under its own weight. In a suspension bridge, the cable also carries the weight of the deck; this changes the overall weight distribution and pulls the cable sections into parabolae.
Here's an explanation!
posted by a mirror and an encyclopedia at 6:44 PM on November 19, 2015 [20 favorites]
Here's an explanation!
posted by a mirror and an encyclopedia at 6:44 PM on November 19, 2015 [20 favorites]
Any article that drags Nolan and TDKR by putting it opposite Final Destination V wins in my book. I don't expect comic book movies to be realistic, but that scene was a record scratch on my suspension of disbelief.
posted by axiom at 6:45 PM on November 19, 2015 [1 favorite]
posted by axiom at 6:45 PM on November 19, 2015 [1 favorite]
Whenever there is a scene in a movie showing something I know well done poorly, it bothers me in exactly this way, so I feel his pain.
posted by Dip Flash at 6:47 PM on November 19, 2015 [3 favorites]
posted by Dip Flash at 6:47 PM on November 19, 2015 [3 favorites]
You'd think the CG boys would at least take a look at Gallopin' Gertie for reference.
posted by Thorzdad at 6:47 PM on November 19, 2015 [3 favorites]
posted by Thorzdad at 6:47 PM on November 19, 2015 [3 favorites]
I 110% support the level of anger brought to the table here.
posted by prefpara at 7:16 PM on November 19, 2015 [2 favorites]
posted by prefpara at 7:16 PM on November 19, 2015 [2 favorites]
Next they'll be saying Pacific Rim wasn't technically accurate.
posted by oluckyman at 7:16 PM on November 19, 2015
posted by oluckyman at 7:16 PM on November 19, 2015
Nolan, who famously hired astrophysicist Kip Thorne to advise him on black holes for Interstellar, failed to hire a sophomore engineering student to explain regular gravity here on Earth.
Something about this really nails Nolan's terrible sense of priorities so much.
posted by shakespeherian at 7:20 PM on November 19, 2015 [7 favorites]
Something about this really nails Nolan's terrible sense of priorities so much.
posted by shakespeherian at 7:20 PM on November 19, 2015 [7 favorites]
They actually did say Pacific Rim wasn't technically accurate.
posted by LionIndex at 7:21 PM on November 19, 2015 [5 favorites]
posted by LionIndex at 7:21 PM on November 19, 2015 [5 favorites]
This is what college does for you! My brother can't even watch gladiator movies.
posted by thelonius at 7:27 PM on November 19, 2015 [4 favorites]
posted by thelonius at 7:27 PM on November 19, 2015 [4 favorites]
Since I work with actual structural engineers, I am forwarding this immediately. Thanks AndrewStephens!
(Our bridge/structural engineers are my favorite engineers; they really seem to enjoy their work. After that is wastewater treatment engineers, who have the worst/best stories and are saving us all from a terrible fate. But I also like the water guys, who have taught me that the reason you should never dive off of a dam is that there is probably large sharp rocks, pieces of metal, or the remains of the previous dam down there. And it's really hard to retrieve your corpse if the lake is deep enough and you're wedged in something).
posted by emjaybee at 7:31 PM on November 19, 2015 [5 favorites]
(Our bridge/structural engineers are my favorite engineers; they really seem to enjoy their work. After that is wastewater treatment engineers, who have the worst/best stories and are saving us all from a terrible fate. But I also like the water guys, who have taught me that the reason you should never dive off of a dam is that there is probably large sharp rocks, pieces of metal, or the remains of the previous dam down there. And it's really hard to retrieve your corpse if the lake is deep enough and you're wedged in something).
posted by emjaybee at 7:31 PM on November 19, 2015 [5 favorites]
Where does this end? I find Raging Bull irritating (and certainly imperfect), despite Scorsese being on my short list of fave directors, because the (much praised!) fight scenes are so unrealistic. (Mefi trauma surgeons please feel free to weigh in.)
posted by oluckyman at 7:37 PM on November 19, 2015
posted by oluckyman at 7:37 PM on November 19, 2015
emjaybee, where do you work? I'd love to hear more infrastructure + engineering-in-the-trenches stories.
posted by glass origami robot at 8:41 PM on November 19, 2015 [1 favorite]
posted by glass origami robot at 8:41 PM on November 19, 2015 [1 favorite]
The anime Tenchi Muyo -- Ryo Ohki! destroys this bridge in its first episode. The suspension cables and the roadbed were severed in the center. The bridge is shown with its towers leaning towards the center, towards each other.
Which is wrong, wrong, wrong! The towers should lean outward, away from each other!! It's always bothered me.
posted by Chocolate Pickle at 8:53 PM on November 19, 2015 [2 favorites]
Which is wrong, wrong, wrong! The towers should lean outward, away from each other!! It's always bothered me.
posted by Chocolate Pickle at 8:53 PM on November 19, 2015 [2 favorites]
Whenever there is a scene in a movie showing something I know well done poorly, it bothers me in exactly this way, so I feel his pain.
WAAAUUGHHH *rips shirt in half, tears off back, throws on floor, stomps on it* There's.A.Movie.That.Has.A.Volcano.Springing.Out.FROM AN OIL SEEP.
posted by barchan at 9:00 PM on November 19, 2015 [3 favorites]
WAAAUUGHHH *rips shirt in half, tears off back, throws on floor, stomps on it* There's.A.Movie.That.Has.A.Volcano.Springing.Out.FROM AN OIL SEEP.
posted by barchan at 9:00 PM on November 19, 2015 [3 favorites]
glass origami robot: I work at a midsize firm in Texas. I do their marketing, so all engineering stories are strictly from a layperson's understanding. Mostly they tell me things like "if you tour a wastewater plant, never ever lick your lips" and "it's actually quite normal for your water to be a little bit radioactive." Also climbing inside ancient rotted elevated water tanks to prove to cities they need to be torn down is scary as fuck but happens more than they'd like. Next time you see a big water storage tank, think about a bunch of guys with flashlights climbing up and peering inside it trying to figure out what's gone wrong. And hoping they don't step on a rusted bit and plunge to their deaths. (they will actually refuse if it looks too bad from the ground, but sometimes, you can't tell till you get up there).
Stormwater engineering is pretty interesting too--that's basically "water that falls from the sky" related things, so runoff, flooding, rain channels, and storm sewers. Nowadays there's a trend for installing water-filtering landscape stuff next to roads, to minimize runoff and clean it up a bit before it hits the storm sewers.
Where I live, Fort Worth, they are currently in the process of sending semi-remote-control videocameras down all the stormwater tunnels checking for cracks and blockages so they can figure out what needs fixing first instead of just waiting till something breaks. The cameras are pretty badass, and do all kinds of readings as well as get video.
posted by emjaybee at 9:13 PM on November 19, 2015 [6 favorites]
Stormwater engineering is pretty interesting too--that's basically "water that falls from the sky" related things, so runoff, flooding, rain channels, and storm sewers. Nowadays there's a trend for installing water-filtering landscape stuff next to roads, to minimize runoff and clean it up a bit before it hits the storm sewers.
Where I live, Fort Worth, they are currently in the process of sending semi-remote-control videocameras down all the stormwater tunnels checking for cracks and blockages so they can figure out what needs fixing first instead of just waiting till something breaks. The cameras are pretty badass, and do all kinds of readings as well as get video.
posted by emjaybee at 9:13 PM on November 19, 2015 [6 favorites]
There's.A.Movie.That.Has.A.Volcano.Springing.Out.FROM AN OIL SEEP.
To be fair, we've already invented a form of drilling for oil that causes earthquakes.
posted by vibratory manner of working at 9:37 PM on November 19, 2015 [2 favorites]
To be fair, we've already invented a form of drilling for oil that causes earthquakes.
posted by vibratory manner of working at 9:37 PM on November 19, 2015 [2 favorites]
Mrs. maxwelton has a very difficult time with "horse" movies for this reason. "He doesn't know how to ride! That's no [fill in horse occupation here]!"
The flip side is you get to discover which actors can ride (for example, Kevin Costner).
posted by maxwelton at 10:12 PM on November 19, 2015 [3 favorites]
The flip side is you get to discover which actors can ride (for example, Kevin Costner).
posted by maxwelton at 10:12 PM on November 19, 2015 [3 favorites]
> Whenever there is a scene in a movie showing something I know well done poorly, it bothers me in exactly this way, so I feel his pain.
I sympathize. This is the same reason why I hate every poker scene in every movie ever - including Rounders, whose poker scenes try too damn hard and overshoot reality -- with three exceptions: the card cheating scene in The Sting, which is the most entertaining poker scene ever filmed, IMO. The underground card game scenes in Michael Clayton are also realistic, which makes sense because they were written by (and feature one of) the writers of Rounders, who played in similar underground NYC games. But really, the poker scene that rings truest to me is the one from House of Games, which may be the only poker scene that actually feels like it takes place in a real game, even though (spoiler alert) it doesn't.
posted by mosk at 11:06 PM on November 19, 2015
I sympathize. This is the same reason why I hate every poker scene in every movie ever - including Rounders, whose poker scenes try too damn hard and overshoot reality -- with three exceptions: the card cheating scene in The Sting, which is the most entertaining poker scene ever filmed, IMO. The underground card game scenes in Michael Clayton are also realistic, which makes sense because they were written by (and feature one of) the writers of Rounders, who played in similar underground NYC games. But really, the poker scene that rings truest to me is the one from House of Games, which may be the only poker scene that actually feels like it takes place in a real game, even though (spoiler alert) it doesn't.
posted by mosk at 11:06 PM on November 19, 2015
I've discovered that some military background and a brief flirt with sports shooting have spoiled most big-budget movies for me, as most Hollywood fare these days involves guns and shooting to some degree. And mostly badly done...
posted by Harald74 at 12:20 AM on November 20, 2015 [2 favorites]
posted by Harald74 at 12:20 AM on November 20, 2015 [2 favorites]
On second thought, maybe I should contribute in stead of just gripe. So, short list of movies and stuff with decent gun handling and shooting: Heat, Saving Private Ryan, Black Hawk Down, Lone Survivor, Strike Back.
Note, I'm not saying that all these movies/shows are great otherwise or even worth your time...
My wife is fluent in Russian and have her own issues with "Russians" in Hollywood movies (though they surprisingly often go to the trouble of recruiting actual Russian-speaking actors).
posted by Harald74 at 12:30 AM on November 20, 2015 [1 favorite]
Note, I'm not saying that all these movies/shows are great otherwise or even worth your time...
My wife is fluent in Russian and have her own issues with "Russians" in Hollywood movies (though they surprisingly often go to the trouble of recruiting actual Russian-speaking actors).
posted by Harald74 at 12:30 AM on November 20, 2015 [1 favorite]
Thorzdad: "You'd think the CG boys would at least take a look at Gallopin' Gertie for reference."
That failure was caused by a very specific design flaw that isn't found on any bridge of note still standing.
posted by Mitheral at 12:40 AM on November 20, 2015
That failure was caused by a very specific design flaw that isn't found on any bridge of note still standing.
posted by Mitheral at 12:40 AM on November 20, 2015
Hey there, mosk - what is your evaluation of the poker scene in Lock, Stock, and Two Smoking Barrels? (edit, forgot which movie had the poker scene)
posted by Meatbomb at 1:24 AM on November 20, 2015
posted by Meatbomb at 1:24 AM on November 20, 2015
You got it right, Meatbomb, Lock, Stock, and Two Smoking Barrels has the rigged card game. Forgot about that one, so I just rewatched a good part of it. The game in the movie is three card brag, which is not a game I've played, so I can't evaluate it too critically. I know it's a forebear to poker but there are also some differences.
Just on the basis of the way they played the hands, though, I think it was better than most - hand values were believable, betting action not too outrageous (for a movie).
There was one detail that bothered me, but I can't find a full clip to confirm it: IIRC they dealt the cards counter-clockwise, but had the betting action proceed clockwise, which confused the hell out of me. But whatever, maybe I'm wrong or maybe that's how brag is played in some places.
tl;dr: Better than many, but I have a few quibbles.
posted by mosk at 2:22 AM on November 20, 2015 [1 favorite]
Just on the basis of the way they played the hands, though, I think it was better than most - hand values were believable, betting action not too outrageous (for a movie).
There was one detail that bothered me, but I can't find a full clip to confirm it: IIRC they dealt the cards counter-clockwise, but had the betting action proceed clockwise, which confused the hell out of me. But whatever, maybe I'm wrong or maybe that's how brag is played in some places.
tl;dr: Better than many, but I have a few quibbles.
posted by mosk at 2:22 AM on November 20, 2015 [1 favorite]
Please don't destroy the suspension of my disbelief.
posted by Splunge at 3:08 AM on November 20, 2015 [2 favorites]
posted by Splunge at 3:08 AM on November 20, 2015 [2 favorites]
Please don't destroy the suspension of my disbelief.
Or at least destroy it in a way that follows the laws of physics.
posted by EndsOfInvention at 3:29 AM on November 20, 2015 [2 favorites]
Or at least destroy it in a way that follows the laws of physics.
posted by EndsOfInvention at 3:29 AM on November 20, 2015 [2 favorites]
but can a structural engineer understand the bridges of Madison County?
posted by ennui.bz at 3:42 AM on November 20, 2015 [3 favorites]
posted by ennui.bz at 3:42 AM on November 20, 2015 [3 favorites]
I've discovered that some military background and a brief flirt with sports shooting have spoiled most big-budget movies for me, as most Hollywood fare these days involves guns and shooting to some degree. And mostly badly done...
I got to shoot a (not very legal) sawed off shotgun a while back, and now almost every movie scene involving one looks super fake to me, with not nearly enough noise and kick and way too much accuracy.
posted by Dip Flash at 5:53 AM on November 20, 2015
I got to shoot a (not very legal) sawed off shotgun a while back, and now almost every movie scene involving one looks super fake to me, with not nearly enough noise and kick and way too much accuracy.
posted by Dip Flash at 5:53 AM on November 20, 2015
Hmmm...If you look closely at the batman bridge, it looks like the cables COULD be connected directly to the bridge span section that isn't being blown up. If that's the case, the support cables should be taught, but if they stay connected, I could see the bridge remaining as-is. (albeit a bit saggy) You'd just have two not-long-enough cable stayed bridges on each bank. https://en.wikipedia.org/wiki/Cable-stayed_bridge - I had to look it up what that would be called, to be honest.
posted by Mr. Big Business at 6:39 AM on November 20, 2015 [1 favorite]
posted by Mr. Big Business at 6:39 AM on November 20, 2015 [1 favorite]
Does anybody watch the television show Defiance? It's set in a futuristic version of St. Louis which has been radically transformed via terraforming (wat?!), but the iconic arch still remains. At one point in the third season [spoiler alert] someone detonates a bomb at the top of the arch as a way of demoralizing the town. The arch is part of the opening title sequence, and from that point on it's shown still standing but with the center section missing. This drove me crazy, because that's totally not how arches work! There's so many things wrong with that image.
posted by Rhomboid at 7:42 AM on November 20, 2015
posted by Rhomboid at 7:42 AM on November 20, 2015
I believe that the arch was constructed from both sides, and the sides were not supported. The two legs are filled with concrete up to a point. Therefore the two sides could stand post bombing.
posted by Midnight Skulker at 7:56 AM on November 20, 2015
posted by Midnight Skulker at 7:56 AM on November 20, 2015
The arch was self-supported until 500 feet or so, I remember watching this video on its construction in school. Quite an amazing feat of work. The entire 2 parts is worth a watch if you've got a half-hour to spare.
posted by glip at 8:02 AM on November 20, 2015 [2 favorites]
posted by glip at 8:02 AM on November 20, 2015 [2 favorites]
Hmmm...If you look closely at the batman bridge, it looks like the cables COULD be connected directly to the bridge span section that isn't being blown up. If that's the case, the support cables should be taught, but if they stay connected, I could see the bridge remaining as-is. (albeit a bit saggy) You'd just have two not-long-enough cable stayed bridges on each bank.
Nuh-uh. Cable-stayed bridges have significant compression along the line of the deck. There is no evidence of a solid enough attachment point for the cables to evenly distribute that load on the deck, and the bridge deck does not look stiff enough to prevent buckling when subjected to those compressive forces.
A common problem among non-engineers is to try to draw comparisions with other (much smaller) things that they are familiar with and assuming that all the issues will scale. In reality, small things have a lot of built-in redundancies and stabilities that disappear on large-scale projects in the name of efficiency.
posted by cardboard at 8:53 AM on November 20, 2015
Nuh-uh. Cable-stayed bridges have significant compression along the line of the deck. There is no evidence of a solid enough attachment point for the cables to evenly distribute that load on the deck, and the bridge deck does not look stiff enough to prevent buckling when subjected to those compressive forces.
A common problem among non-engineers is to try to draw comparisions with other (much smaller) things that they are familiar with and assuming that all the issues will scale. In reality, small things have a lot of built-in redundancies and stabilities that disappear on large-scale projects in the name of efficiency.
posted by cardboard at 8:53 AM on November 20, 2015
but can a structural engineer understand the bridges of Madison County?
Why, yes, they can!
posted by Monday, stony Monday at 9:23 AM on November 20, 2015
Why, yes, they can!
posted by Monday, stony Monday at 9:23 AM on November 20, 2015
cardboard: " In reality, small things have a lot of built-in redundancies and stabilities that disappear on large-scale projects in the name of efficiency."
I thought it was in the name of the square-cube law?
posted by RobotHero at 9:30 AM on November 20, 2015
I thought it was in the name of the square-cube law?
posted by RobotHero at 9:30 AM on November 20, 2015
Watching Gravity was pretty infuriating after having tried to dock in Kerbal Space Program.
posted by ckape at 10:07 AM on November 20, 2015 [3 favorites]
posted by ckape at 10:07 AM on November 20, 2015 [3 favorites]
trained assassins catch up to hero in a hallway, deploy bullpups and shotguns; everybody misses. Sigh.
(I go make some popcorn, come back during the car chase. I cannot enjoy the action now, because mrs mule keeps whining about how they're running over all those innocent civilians. Next time I'm gonna look see if Netflix has any old Star Trek movies.)
posted by mule98J at 12:48 PM on November 20, 2015
(I go make some popcorn, come back during the car chase. I cannot enjoy the action now, because mrs mule keeps whining about how they're running over all those innocent civilians. Next time I'm gonna look see if Netflix has any old Star Trek movies.)
posted by mule98J at 12:48 PM on November 20, 2015
Some college friends of mine were fencers, and hated most swordfighting scenes. (At some point this year I read that The Princess Bride has some of the best.)
Jalopnik today has a thread devoted to the worst car scenes. It kicks off with one where the vehicle actually changes (different generations of the same vehicle) from shot to shot.
posted by pmurray63 at 1:53 PM on November 20, 2015
Jalopnik today has a thread devoted to the worst car scenes. It kicks off with one where the vehicle actually changes (different generations of the same vehicle) from shot to shot.
posted by pmurray63 at 1:53 PM on November 20, 2015
Next time I'm gonna look see if Netflix has any old Star Trek movies
The ones where ships with infinite energy density fuel travel faster than the speed of light?
posted by justsomebodythatyouusedtoknow at 2:31 PM on November 20, 2015 [1 favorite]
The ones where ships with infinite energy density fuel travel faster than the speed of light?
posted by justsomebodythatyouusedtoknow at 2:31 PM on November 20, 2015 [1 favorite]
In this chapter, Sam Lawton is stuck in traffic on the North Bay Bridge in western New York (played by Vancouver’s Lions Gate Bridge, the only non-iconic bridge on this list)
Sez who? (North Vancouver resident who sees the bridge as iconic indeed. Ever heard of Lion's Gate Studios?)
Ah, whatever.
posted by Turtles all the way down at 5:17 PM on November 20, 2015 [3 favorites]
Sez who? (North Vancouver resident who sees the bridge as iconic indeed. Ever heard of Lion's Gate Studios?)
Ah, whatever.
posted by Turtles all the way down at 5:17 PM on November 20, 2015 [3 favorites]
Imagine stringing a clothesline between two buildings and putting some shirts out to dry. Now, cut the line in the middle. In our world, the line loses all its capacity and the shirts all fall to the ground. In Christopher Nolan’s world, the clothesline is unharmed and, who knows, may actually be stronger.
posted by storybored at 6:44 PM on November 20, 2015 [1 favorite]
posted by storybored at 6:44 PM on November 20, 2015 [1 favorite]
Another problem in that video clip from Final Destination V is when the guy comes out of the bus bathroom just as it starts to fall off the broken bridge into the water. Then as they free-fall down into the water, his face is tightly plastered against the windscreen despite being in almost a zero gravity situation.
posted by exogenous at 8:17 AM on November 24, 2015
posted by exogenous at 8:17 AM on November 24, 2015
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posted by Dysk at 6:18 PM on November 19, 2015 [8 favorites]