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What Are Traffic Waves and Why Do They Happen So Much?

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Re: What Are Traffic Waves and Why Do They Happen So Much?

#11

Post by jacquesm »

stormbrew wrote: post #8
orik wrote: post #7

Whenever the topic of self driving cars comes up in conversation I let people know I think self driving cars are going to solve a lot of our traffic woes. I'm not sure if a model exists yet for cars 'putting out' traffic waves, but I'm sure once we have self driving cars and they start talking to each other this is going to be of great interest. I'm hoping we can effectively 'micro' away some degree of congestion.

I think people overstate the degree to which self-driving cars will actively 'talk' to each other. And I actually think it's somewhat detrimental to advocating for self-driving cars, because the immediate thought is that communication acting as a channel for malware. And that's a fairly justified fear. In the end, I think most of the communication will just be in terms of the fact that self-driving cars interacting w…

And that's assuming error free communications, near latency free communications and non-congestion as well as perfect hardware.

Is 'no signal' the same as 'no other cars' or 'broken radio(s)'?

Self driving cars have all the elements of a distributed computing system only now it's moving at a pretty good clip and lives are at stake. 'Move fast and break something' is very bad advice and 99.999% uptime is not going to cut it.

Hard enough to get autonomous (pun not intended) systems right, much harder to make systems that communicate between vehicles right. The best way would be to not rely on inter-vehicle communication but to only work with the signals that the car can pick up from the environment.

At least that data will be somewhat trustworthy because you have some idea about the integrity of the system.

Re: What Are Traffic Waves and Why Do They Happen So Much?

#12

Post by smhg »

kokey wrote: post #6

I find this happens a lot more in some countries than others, and it's not down to levels of traffic on the road, it's down to driving habits. I think the UK has done well with driver education and variable speed limits to mitigate this, and zipper merging is the norm.

Is it based on your own experience? Or you read it somewhere?

In which countries did it happen more?

Re: What Are Traffic Waves and Why Do They Happen So Much?

#13

Post by SomeStupidPoint »

jacquesm wrote: post #11
stormbrew wrote: post #8

Earlier quoted context omitted.

I think people overstate the degree to which self-driving cars will actively 'talk' to each other. And I actually think it's somewhat detrimental to advocating for self-driving cars, because the immediate thought is that communication acting as a channel for malware. And that's a fairly justified fear. In the end, I think most of the communication will just be in terms of the fact that self-driving cars interacting w…

And that's assuming error free communications, near latency free communications and non-congestion as well as perfect hardware. Is 'no signal' the same as 'no other cars' or 'broken radio(s)'? Self driving cars have all the elements of a distributed computing system only now it's moving at a pretty good clip and lives are at stake. 'Move fast and break something' is very bad advice and 99.999% uptime is not going to…

I'm not sure what either you or the person above you adds to the topic of traffic congestion.

You certainly wouldn't depend on communication for collision avoidance, but it's still likely that cars will have beacons which alert other cars to their existence, and it has nothing to do with -- at the range of kilometers -- taking turns broadcasting how many cars you see around you (immediately, ie, traffic packing), your velocity, and your location.

The other self-driving cars can listen for beacons about congestion, and adjust strategic parameters (such as speed) in a safe manner. While I wouldn't trust a random driver telling me to break suddenly, why not take a random tip that there's a slowdown and adjust my driving to help mitigate the jam, especially if 50 other people agree that there's a jam there?

Re: What Are Traffic Waves and Why Do They Happen So Much?

#14

Post by rajivm »

stormbrew wrote: post #8
orik wrote: post #7

Whenever the topic of self driving cars comes up in conversation I let people know I think self driving cars are going to solve a lot of our traffic woes. I'm not sure if a model exists yet for cars 'putting out' traffic waves, but I'm sure once we have self driving cars and they start talking to each other this is going to be of great interest. I'm hoping we can effectively 'micro' away some degree of congestion.

I think people overstate the degree to which self-driving cars will actively 'talk' to each other. And I actually think it's somewhat detrimental to advocating for self-driving cars, because the immediate thought is that communication acting as a channel for malware. And that's a fairly justified fear. In the end, I think most of the communication will just be in terms of the fact that self-driving cars interacting w…

While I largely agree, I think that some layer of _untrusted_ communication could be beneficial. Think along the lines of how turn signals & honking can benefit humans. Similar types of information could be conveyed more precisely "over the air", even if it was not presumed to be perfect (i.e. just likes human's signals aren't and a smart car isn't going to trust someone's turn signal, but it might react to it). Examples of this could be 1) relayed traffic ahead (more time to break smoothly) 2) lane switching plans (cars can coordinate such that it reduces slow downs & conflicts) etc. This is very similar to how network layer algorithms behave (i.e. TCP can hint to slow down, but you don't have to listen).

Re: What Are Traffic Waves and Why Do They Happen So Much?

#15

Post by blunte »

One point that seems often forgotten (or undervalued) is the great different in deceleration vs acceleration. Cars (especially driven by humans) decelerate much more quickly than they accelerate. I didn't get the impression from the simulation that this difference was realistically represented. I think reality is even worse than this simulation illustrates.

Re: What Are Traffic Waves and Why Do They Happen So Much?

#16

Post by tirant »

Somehow I always knew this, and I was always driving in a specific manner to combat this effect: I always leave a buffer of space between my car and front car, and whenever I observe oscillations in the car in front, I use my buffer to let my speed oscillate as less as possible.

Re: What Are Traffic Waves and Why Do They Happen So Much?

#18

Post by melloclello »

stormbrew wrote: post #8
orik wrote: post #7

Whenever the topic of self driving cars comes up in conversation I let people know I think self driving cars are going to solve a lot of our traffic woes. I'm not sure if a model exists yet for cars 'putting out' traffic waves, but I'm sure once we have self driving cars and they start talking to each other this is going to be of great interest. I'm hoping we can effectively 'micro' away some degree of congestion.

I think people overstate the degree to which self-driving cars will actively 'talk' to each other. And I actually think it's somewhat detrimental to advocating for self-driving cars, because the immediate thought is that communication acting as a channel for malware. And that's a fairly justified fear. In the end, I think most of the communication will just be in terms of the fact that self-driving cars interacting w…

I expect in the short run we'll see different tribes of self-driving cars - say Google vs. Uber - who will actively communicate cooperatively with their in-group, but actually compete against the out-group, depending upon whether or not their host companies decide to cooperate or not.

In the long run, I expect cars to become smart enough to be self-owning, in which case it's every car for himself.

Re: What Are Traffic Waves and Why Do They Happen So Much?

#19

Post by kokey »

smhg wrote: post #12
kokey wrote: post #6

I find this happens a lot more in some countries than others, and it's not down to levels of traffic on the road, it's down to driving habits. I think the UK has done well with driver education and variable speed limits to mitigate this, and zipper merging is the norm.

Is it based on your own experience? Or you read it somewhere? In which countries did it happen more?

The last time I counted, I have driven in 12 different countries. I found this certainly happens a lot in South Africa and a bit in various parts of Spain and Ireland. It seems to happen a lot less in the UK and Portugal.

Re: What Are Traffic Waves and Why Do They Happen So Much?

#20

Post by reuven »

A model of this is included in the NetLogo models library, which comes with the NetLogo modeling language: http://ccl.northwestern.edu/netlogo/models/TrafficBasic

It's fun to see children (and adults!) play with the controls on this model, experimenting with different factors that they think might eventually reduce the congestion.

This model is also a great way to introduce kids to complex systems, in which the large-scale results aren't necessarily as obvious as the individual actions that lead to those results.

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