+Dominic Clarke Imagine that one route has a big capacity, so that it can accommodate all incoming traffics. So, regardless the amount of vehicle, each of them can travel with free flow speed. therefore, the travel time is not affected by the traffic.
@@Cavball9 Because its not possible? You can think of many reasons why a road simply could not be expanded. It actually makes a lot of sense. A 6 lane highway (that could accommodate all traffic) turning into a 4 lane highway that goes through the city. You can't expand the highway without destroying buildings. Maybe the highway goes between mountains. Maybe you don't have the capital to build another lane.
@@gruskymeerkat11 But how would it be impossible in every case? That's my critique - I think the assumed premise is bunk. It certainly could be difficult or infeasible in many cases, but other cases may be incredibly easy and efficient. Point being - while there are many situations where Braess' applies and should be used in the decision-making process, I feel applying it as some end-all, be-all for traffic analyses is intellectually irresponsible.
Well, no one ever replied, so in case you never got an answer: Roundabouts are an example of road control that work better the less traffic there is. Which is why for high traffic area's, they tend to become quite massive for it to keep working. Yet there is a minimal point where roundabouts actually could add traffic and a straight road or some traffic lights simply would have worked much better overall. I think everyone knows a situation when they have been at a roundabout and actually were stuck because people kept driving on, where a traffic light would have sorted every road on that intersection much more fairly.
Think about the 20 min roads as massively large, and the only variable is LENGTH. Whereas the T/10 roads have fewer lanes, but are half as long as the 20 min roads, which means that the amount of traffic constrains them. Therefore if traffic fills them up, they become 20 minute roads rather than 10 min roads.
He said that there are 200 drivers and they are divided evenly between each route, so that the top route has 200/2=100 drivers, and likewise the bottom route has 100 drivers. When we divide this value by 10, the result is 100/10 = 10.
In basic electricity...it's similar to a wheatstone bridge...but the bridge is not connected, just measured. Google tries this method...I was on a main highway and there was a back up at an intersection. Google maps calculated that a back road around the backup that brought me back into the back up, but right before the intersection would save time. A rude answer to get around everyone else in line.
At first I wondered why this video had so many dislikes. And then I check the comments and have understood everything: people can't understand something, start thinking it is some fallacy and dislike the video in the result. Jesus...
I would love to see the real traffic analysis that resulted in the road removal because this explanation does not apply directly. There is no such thing as a road that, when traveled by only one car and being the same length as a 20-minute road, takes only 1/10 of a minute to drive. I have no doubt that the reason was directly similar, but I would like to see the actual math.
It's isn't maths as such here, but human behaviour. In reality there isn't just the one car on the road though. There are hundreds/thousands of cars in reality in cities. All with drivers wanting to go the fastest route. Thus choking said fastest route.
This is just a mathematical model, however there are many examples where this worked in real-life scenarios. You can think of it like that: the road that takes T/10 minutes to take is small road where traffic heavily influences the travel time and the road where it always takes 20 minutes to travel by is a wide highway.
There are example of the phenomenon on Wikipedia. As the other commenter pointed out, this is just a model. Not all aspect are going to be true to life. The key feature represented T/10 equation is not necessarily the specific numerical value (i.e. nobody is claiming that you could drive a "20 minute road" in 1/th of a minute), but rather that travel time is dependent on total traffic volume, which absolutely is true in the real world. That's why driving at rush hour on a Monday, you're typically find things a bit slower than midday on the weekend. Also, I think you have you're reasoning backwards. The way to conceptualize this situation is not that something like an hour long drive can be done 6 minutes if nobody else is on the road. Obviously no car is going to be able to drive 5 miles in say 1 minute. Rather, the point is that what would normally be a 5 minute drive when no cars on on the road can easily become a 30 minute drive when there is a ton of traffic. Again, you probably have experience with this yourself. In other words, this model is not saying that your car goes *faster* than it's *normal* speed when there are *no* other cars on the road. It's saying that your car goes *slower* than it's *normal* speed when there are *a lot* of other cars on the road.
@@cwm9686 This video presented "actual" math. If you're talking about an actual real world example of this occurring, that's a different story, and this video obviously doesn't provide that, but the math in here is "actual" math and the reasoning is perfectly valid. In math you often show that something is possible under certain circumstances, and that's exactly what this model has done. Real world examples of this phenomenon may be common or they may be rare, but the point of Braess' paradox is just to show that it is conceptually possible to run into scenarios where adding more routes to a network actually slows things down, and the math used in the video successfully demonstrates that. Whether the numbers come from a real world example or not is irrelevant. That being said, the Wikipedia article does mention a few real world examples without getting into the numerical details. Apparently the phenomenon has been observed when some roads in New York city were closed. The article mentions a few other examples too.
ahem. The first example assumes a lot of stuff. If the driver's would estimate the time locally then the answer would be different. More specifically, the bottom road would get ALL the traffic. (the first half of the bottom road would be faster until the last driver takes the bottom road)
maybe they meet in the middle but prior to adding the route it has a barrier. the route is created by removing the barrier. Since the routes touch it takes zero time to travel (not counting potential traffic light or stop sign to control flow)
That is how some systems work, but they can also work in reverse. For example, keeping the road open for the 20/20 side at all times could save you a lot of traffic because there are people who dont care about time and just want to save gas. Let alone that if, somehow, traffic peaks over 200, it would actually be the faster route too.
EElACONDER It represents a shortcut. It doesn't have to take 0 time. You can change the delay for taking the shortcut to 2 minutes and lower the number of cars to, for example, 140. Same problem happens. All on the Inner route: Inner route: 140/10 + 2 + 140/10 = 30 min Upper route: 20 + 140/10 = 34 min Lower route: 140/10 + 20 = 34 min -> No incentive for someone on the Inner route to switch to one of the outer ones. Half on each outer route: Inner route: 70/10 + 2 + 70/10 = 16 min Upper route: 20 + 70/10 = 27 min Lower route: 70/10 + 20 = 27 min -> Everyone would prefer to use the Inner route, since it's faster, and changes to it. Everyone ends up taking 30 min instead of the current 27 min.
They all take the road that MIGHT be better, rather than the road that is only better if MOST agree to split up. Each person makes their own decision, therefore it never makes sense for any ONE person to create the best conditions for the whole.
How can they all go through the same route if the second one will be more efficient if you are the only one on it? People tend to choose the better option for themselves.
@@Kokurorokuko You have to imagine one as a constant and the other as a variable. Imagine one as a road that can handle any amount of traffic, but it a longer route, therefore, assuming you obey the speed limit, it will always take the same amount of time. The other road is a shorter route, but there MIGHT be traffic that slows it down. As you said, the shorter route will only be as slow as the long route, because if it gets slower, people will simply switch back to the longer route. But once they equalize, people have no reason to take the longer route, because the longer route has no POSSIBILITY of taking less time than the shorter route. The shorter route is a variable that depends on traffic. The longer route is a constant.
If vertical line is equal to 0, then the upper and lower routes are almost parallel, and the distance of "T/10" is equal to the distance of "20". If "routes are equally good", then 100 cars will travel "20" in the same amount of time as "T/10". Your "explanation" or "solution" is a total BS nonsense.
the vertical line being 0 does not necessarily mean both routes are parallel. all it means is that they are next to each other or cross over each other at some point.
The reason this works in real life is NOT because of mathematical stuff. It's pure psychology: people prefer to take popular/distinctive streets over side streets. Therefore, traffic isn't evenly disbursed like it should be.
It's mathematically proven as well proven in practice. And if that would be not enough Braess Paradox is still very optimistic. As it does not take into account Pigou-Knight-Downs paradox or Lewis-Mogridge Position. Together it pretty much say traffic get exponentially worse with more or better roads.
The first part ("pure psychology") is not always accurate. There is a similar phenomenon in power grids related to cascading failures. Its completely physical in nature and no human behavior is involved. In the power grid case psychology has nothing to do with it.
> Together it pretty much say traffic get exponentially worse with more or better roads. If that was true, it would be beneficial for traffic to close all roads. That can't be true.
@@adisarid Similar flaws can pop up in any pathfinding algorithm, even if the pathfinding algorithm is defined by say, physical laws, in the case of how electricity, or water flowing downhill will seek the shortest path, rather than analytical rules, like in the human brain, or a computer simulation. Any pathfinding algorithm that is too simple is likely to funnel traffic right into a bottleneck.
Each INDIVIDUAL part takes the fastest route. That's how it happens. It's not psychology. It's because the individual pieces can't inform a decision for the whole. Everyone is acting perfectly logically on an individual level. It's like when people try and drive with big gaps on the freeway to eliminate traffic, there are always drivers who fill in space because it benefits them at that moment.
a road of 0 time has no length therefore you put all your 200 people onto one road instead of splitting them into two, that is why it took 30 minutes for 100 people but 40 minutes for 200 people to get from A to B. I can't believe you posted this with your fancy pencil work
That's the point though. People *choose* that routing , not that they are not forced onto the initially faster route, hence why it slows down. A zero length/time road simplifies the explanation, that's all. The same will apply if 'bypass' road road is 2 mins long. Then journeys will take 42mins if everyone goes the quickest way. In reality roads always fill to capacity and traffic speeds never increase and can actually decrease due to induced demand and pinch points elsewhere. www.wired.com/2014/06/wuwt-traffic-induced-demand/
Why ruin a decent movie with background music?????? So annoying I had to stop watching. Consider re-uploading this with out music if you want more people to watch longer and subscribe.
Using T for TRAFIC in any kind of equation that also includes time is chaotic evil at its best.
Thank you so much, I struggled to understand this concept and I have my exam tomorrow. You helped me a lot !! Very nice and simple explanation !!!
Technically, If you travel by yourself, you can get to the other point in 0.2sec.
That' why paradox is working. All humans think the same.
This is the fourth video I've watched about this paradox, and for some reason, I finally understand it when explained this way.
Guess using a more realistic model instead of abstract equations helped
Why would one road be dependant on the amount of vehicles on it, yet another has a fixed amount of time?
+Dominic Clarke Imagine that one route has a big capacity, so that it can accommodate all incoming traffics. So, regardless the amount of vehicle, each of them can travel with free flow speed. therefore, the travel time is not affected by the traffic.
@@jauharialafi Your response is true, but the problem lies with the premise: why not expand the t/10 segments to accommodate all incoming traffic?
@@Cavball9 Because its not possible? You can think of many reasons why a road simply could not be expanded. It actually makes a lot of sense. A 6 lane highway (that could accommodate all traffic) turning into a 4 lane highway that goes through the city. You can't expand the highway without destroying buildings. Maybe the highway goes between mountains. Maybe you don't have the capital to build another lane.
@@gruskymeerkat11 But how would it be impossible in every case? That's my critique - I think the assumed premise is bunk. It certainly could be difficult or infeasible in many cases, but other cases may be incredibly easy and efficient.
Point being - while there are many situations where Braess' applies and should be used in the decision-making process, I feel applying it as some end-all, be-all for traffic analyses is intellectually irresponsible.
@@Cavball9 It isn't intended to be used in all situations. Even in this short video, it is highlighted that SPECIFIC roads cause this paradox to occur
Wait! I still have 25 horses I have to deal with on my living room floor. I'm still racing them to see who's the fastest. They're wearing out the rug.
HELP. Where does the 10 from the T/10 come from??? What does it mean???Is it the capacity of cars in the road???
Well, no one ever replied, so in case you never got an answer:
Roundabouts are an example of road control that work better the less traffic there is. Which is why for high traffic area's, they tend to become quite massive for it to keep working. Yet there is a minimal point where roundabouts actually could add traffic and a straight road or some traffic lights simply would have worked much better overall.
I think everyone knows a situation when they have been at a roundabout and actually were stuck because people kept driving on, where a traffic light would have sorted every road on that intersection much more fairly.
@@Predated2 Roundabout can also have traffic lights for busy times.
The corollary is that many traffic lights would be better replaced by roundabouts.
Think about the 20 min roads as massively large, and the only variable is LENGTH.
Whereas the T/10 roads have fewer lanes, but are half as long as the 20 min roads, which means that the amount of traffic constrains them. Therefore if traffic fills them up, they become 20 minute roads rather than 10 min roads.
He said that there are 200 drivers and they are divided evenly between each route, so that the top route has 200/2=100 drivers, and likewise the bottom route has 100 drivers. When we divide this value by 10, the result is 100/10 = 10.
In basic electricity...it's similar to a wheatstone bridge...but the bridge is not connected, just measured. Google tries this method...I was on a main highway and there was a back up at an intersection. Google maps calculated that a back road around the backup that brought me back into the back up, but right before the intersection would save time. A rude answer to get around everyone else in line.
At first I wondered why this video had so many dislikes. And then I check the comments and have understood everything: people can't understand something, start thinking it is some fallacy and dislike the video in the result. Jesus...
Is this related to Simpson's paradox? Dividing a group into subsets can give different statistics than keeping it whole.
I would love to see the real traffic analysis that resulted in the road removal because this explanation does not apply directly. There is no such thing as a road that, when traveled by only one car and being the same length as a 20-minute road, takes only 1/10 of a minute to drive. I have no doubt that the reason was directly similar, but I would like to see the actual math.
It's isn't maths as such here, but human behaviour.
In reality there isn't just the one car on the road though. There are hundreds/thousands of cars in reality in cities. All with drivers wanting to go the fastest route. Thus choking said fastest route.
This is just a mathematical model, however there are many examples where this worked in real-life scenarios. You can think of it like that: the road that takes T/10 minutes to take is small road where traffic heavily influences the travel time and the road where it always takes 20 minutes to travel by is a wide highway.
There are example of the phenomenon on Wikipedia. As the other commenter pointed out, this is just a model. Not all aspect are going to be true to life. The key feature represented T/10 equation is not necessarily the specific numerical value (i.e. nobody is claiming that you could drive a "20 minute road" in 1/th of a minute), but rather that travel time is dependent on total traffic volume, which absolutely is true in the real world. That's why driving at rush hour on a Monday, you're typically find things a bit slower than midday on the weekend. Also, I think you have you're reasoning backwards. The way to conceptualize this situation is not that something like an hour long drive can be done 6 minutes if nobody else is on the road. Obviously no car is going to be able to drive 5 miles in say 1 minute. Rather, the point is that what would normally be a 5 minute drive when no cars on on the road can easily become a 30 minute drive when there is a ton of traffic. Again, you probably have experience with this yourself. In other words, this model is not saying that your car goes *faster* than it's *normal* speed when there are *no* other cars on the road. It's saying that your car goes *slower* than it's *normal* speed when there are *a lot* of other cars on the road.
Yes... I get that. I still want to see an actual study with actual math.
@@cwm9686 This video presented "actual" math. If you're talking about an actual real world example of this occurring, that's a different story, and this video obviously doesn't provide that, but the math in here is "actual" math and the reasoning is perfectly valid. In math you often show that something is possible under certain circumstances, and that's exactly what this model has done. Real world examples of this phenomenon may be common or they may be rare, but the point of Braess' paradox is just to show that it is conceptually possible to run into scenarios where adding more routes to a network actually slows things down, and the math used in the video successfully demonstrates that. Whether the numbers come from a real world example or not is irrelevant.
That being said, the Wikipedia article does mention a few real world examples without getting into the numerical details. Apparently the phenomenon has been observed when some roads in New York city were closed. The article mentions a few other examples too.
ahem. The first example assumes a lot of stuff. If the driver's would estimate the time locally then the answer would be different. More specifically, the bottom road would get ALL the traffic. (the first half of the bottom road would be faster until the last driver takes the bottom road)
It's mathematically proven as well proven in practice.
While the paradox is correct, this particular example is bad since practically no road takes 0 minutes.
maybe they meet in the middle but prior to adding the route it has a barrier. the route is created by removing the barrier. Since the routes touch it takes zero time to travel (not counting potential traffic light or stop sign to control flow)
I wonder if The Braess Paradox exist in Quantum Mechanics.
Maybe close the road, when it's more than 150 people who want to get from A to B. Under 150, it's actually faster.
That is how some systems work, but they can also work in reverse. For example, keeping the road open for the 20/20 side at all times could save you a lot of traffic because there are people who dont care about time and just want to save gas. Let alone that if, somehow, traffic peaks over 200, it would actually be the faster route too.
Can you explain to me what the road changing you to the other road instantaneously represents ?
EElACONDER It represents a shortcut. It doesn't have to take 0 time.
You can change the delay for taking the shortcut to 2 minutes and lower the number of cars to, for example, 140. Same problem happens.
All on the Inner route:
Inner route: 140/10 + 2 + 140/10 = 30 min
Upper route: 20 + 140/10 = 34 min
Lower route: 140/10 + 20 = 34 min
-> No incentive for someone on the Inner route to switch to one of the outer ones.
Half on each outer route:
Inner route: 70/10 + 2 + 70/10 = 16 min
Upper route: 20 + 70/10 = 27 min
Lower route: 70/10 + 20 = 27 min
-> Everyone would prefer to use the Inner route, since it's faster, and changes to it. Everyone ends up taking 30 min instead of the current 27 min.
This is mere foolishness, if all 200 drivers take same route in the first case, then the total time will be 40mins only.
They all take the road that MIGHT be better, rather than the road that is only better if MOST agree to split up.
Each person makes their own decision, therefore it never makes sense for any ONE person to create the best conditions for the whole.
How can they all go through the same route if the second one will be more efficient if you are the only one on it? People tend to choose the better option for themselves.
@@Kokurorokuko
You have to imagine one as a constant and the other as a variable.
Imagine one as a road that can handle any amount of traffic, but it a longer route, therefore, assuming you obey the speed limit, it will always take the same amount of time.
The other road is a shorter route, but there MIGHT be traffic that slows it down.
As you said, the shorter route will only be as slow as the long route, because if it gets slower, people will simply switch back to the longer route.
But once they equalize, people have no reason to take the longer route, because the longer route has no POSSIBILITY of taking less time than the shorter route.
The shorter route is a variable that depends on traffic.
The longer route is a constant.
Hey this looks like wheatstone bridge.
You dont make more roads, you widen the roads to get more lanes
Widening roads has proven ineffective too, at least on major highways used for commuting. It's impossible to out build congestion unfortunately.
@@Droidman1231 Then you go double-decking! LOL
@@n40798 doesent work either
And in cities that's almost never possible.
Flying cars then
If vertical line is equal to 0, then the upper and lower routes are almost parallel, and the distance of "T/10" is equal to the distance of "20". If "routes are equally good", then 100 cars will travel "20" in the same amount of time as "T/10". Your "explanation" or "solution" is a total BS nonsense.
the vertical line being 0 does not necessarily mean both routes are parallel. all it means is that they are next to each other or cross over each other at some point.
This reminds me of THIS:
ruclips.net/video/tmE2Ytq0-SE/видео.html
SimCity SNES Bern(Traffic)
The reason this works in real life is NOT because of mathematical stuff. It's pure psychology: people prefer to take popular/distinctive streets over side streets. Therefore, traffic isn't evenly disbursed like it should be.
It's mathematically proven as well proven in practice.
And if that would be not enough Braess Paradox is still very optimistic. As it does not take into account Pigou-Knight-Downs paradox or Lewis-Mogridge Position.
Together it pretty much say traffic get exponentially worse with more or better roads.
The first part ("pure psychology") is not always accurate. There is a similar phenomenon in power grids related to cascading failures. Its completely physical in nature and no human behavior is involved. In the power grid case psychology has nothing to do with it.
> Together it pretty much say traffic get exponentially worse with more or better roads.
If that was true, it would be beneficial for traffic to close all roads. That can't be true.
@@adisarid Similar flaws can pop up in any pathfinding algorithm, even if the pathfinding algorithm is defined by say, physical laws, in the case of how electricity, or water flowing downhill will seek the shortest path, rather than analytical rules, like in the human brain, or a computer simulation. Any pathfinding algorithm that is too simple is likely to funnel traffic right into a bottleneck.
Each INDIVIDUAL part takes the fastest route. That's how it happens.
It's not psychology. It's because the individual pieces can't inform a decision for the whole.
Everyone is acting perfectly logically on an individual level.
It's like when people try and drive with big gaps on the freeway to eliminate traffic, there are always drivers who fill in space because it benefits them at that moment.
a road of 0 time has no length therefore you put all your 200 people onto one road instead of splitting them into two, that is why it took 30 minutes for 100 people but 40 minutes for 200 people to get from A to B.
I can't believe you posted this with your fancy pencil work
That's the point though. People *choose* that routing , not that they are not forced onto the initially faster route, hence why it slows down. A zero length/time road simplifies the explanation, that's all.
The same will apply if 'bypass' road road is 2 mins long. Then journeys will take 42mins if everyone goes the quickest way.
In reality roads always fill to capacity and traffic speeds never increase and can actually decrease due to induced demand and pinch points elsewhere.
www.wired.com/2014/06/wuwt-traffic-induced-demand/
if it had length it would be even longer. So this simplification is in favor of people who think something is wrong here.
That's all??? Ok
Just stop handing out licenses to slow ass asian drivers.. problem solved XD
Why ruin a decent movie with background music?????? So annoying I had to stop watching. Consider re-uploading this with out music if you want more people to watch longer and subscribe.