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How traffic actually works

jliszka.github.io

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Re: How traffic actually works

#131

Post by bagosm »

susi22 wrote: post #86

This article is so horribly incorrect and fails right at the very beginning with the wrong assumptions and a idea that isn't thought through. What the author forgot is to take by far the most important variable into account: SPEED So let's quote the author: "The important fact: there is a limit to the number of cars that can pass by a given point on the highway in a given amount of time, and that limit is one car eve…

Please allow me to unify the two theories, because both seem correct.

The free flow merge theory applies only in open areas with maybe temporary blocks that flow is unrestricted in any other way.

The no-merge theory applies on situations with traffic lights (and/or other special flow control such as a policeman or toll booths etc) where you suppose there are cut-off points that allow a specific number of vehicles per second.

Re: How traffic actually works

#132

Post by jere »

cbr wrote: post #125
jere wrote: post #99

I'm having a very hard time accepting the claims of original article, "The Physics Behind Traffic Jams." Recently, I've tried to perform a few basic hypermiling techniques, especially "timing a light": if I'm the first car to encounter a red light, I leave extra space and can sometimes be moving through the light at 20mph or more when it turns green instead of stopped. It seems analogous to leaving space in front of…

Vehicle sensing systems mean the basic assumption of light timing no longer holds: when you get to the light can affect how long you have to wait.

I understand, but I'm not making the assumption. I'm talking about roads I drive everyday that are clearly on timers and I've even got good estimates on how long the cycles last.

Re: How traffic actually works

#133

Post by SilasX »

jerf wrote: post #79
analyst74 wrote: post #45

Earlier quoted context omitted.

What author is trying to argue against is the idea of "smoothing-the-wave", which he does prove in his overly complicated article. Yes, there is too much rambling for making a point, yes the tone of title is quite arrogant / link-baity. But this terrible essay did prove the point: smoothing the wave is not going to make you go faster.

I'm not sure who actually thought that "smoothing the wave" did make you actually go faster though, since a moment's thought shows that "going faster" would necessarily involve going through the bumper of the car in front of you. I think it's about a "laminar" traffic flow being a lot less annoying and dangerous to drive in, if you are going to go slow. I think he fell down on his own argument when he claims that doi…

>I'm not sure who actually thought that "smoothing the wave" did make you actually go faster though,

Probably all the people that passed around the critiqued link and suggested that it gives a way to improve traffic flow?

Re: How traffic actually works

#135

Post by jwallaceparker »

thrownaway2424 wrote: post #74
jwallaceparker wrote: post #53

I wish more drivers would follow the driving etiquette that advises one to "stay right except to pass." On every highway trip I see countless cars camped out in the left lane but moving at the same rate as the rest of traffic. One should only use the left lane for passing. Otherwise, stay right. Traffic flows smoothly when people follow this system.

In practice this cannot work. "Except to pass" allows for any nonzero differential speed. Someone will be doing 55MPH in the rightmost lane and someone will pass them at 55.1MPH, and someone will pass them in the left lane at 55.2MPH.

This is fine as long as each driver migrates back to the right as soon as feasible.

Re: How traffic actually works

#137

Post by SilasX »

chrisa wrote: post #11
bryanlarsen wrote: post #5

The central assumption for this argument is that the average time between cars is fairly consistent no matter the environment; small changes to this time do not matter. However, on a congested road very small changes can have huge effects. IIRC, one study showed that a 1% decrease in the number of vehicles resulted in a 28% decrease in commute time.

This doesn't sound like the same study, but it's similar: a TED talk about how adding a fee for bridges in Stockholm reduced the number of cars by 20% and effectively eliminated congestion: http://www.ted.com/talks/jonas_eliasson_how_to_solve_traffic...

"Yeah, so, it turns out that charging for something prevents its overuse."

'WOW! REALLY?'

Re: How traffic actually works

#139

Post by susi22 »

bagosm wrote: post #131
susi22 wrote: post #86

This article is so horribly incorrect and fails right at the very beginning with the wrong assumptions and a idea that isn't thought through. What the author forgot is to take by far the most important variable into account: SPEED So let's quote the author: "The important fact: there is a limit to the number of cars that can pass by a given point on the highway in a given amount of time, and that limit is one car eve…

Please allow me to unify the two theories, because both seem correct. The free flow merge theory applies only in open areas with maybe temporary blocks that flow is unrestricted in any other way. The no-merge theory applies on situations with traffic lights (and/or other special flow control such as a policeman or toll booths etc) where you suppose there are cut-off points that allow a specific number of vehicles per…

I'm sorry. I didn't mean to lay out any "theory". I really just meant to criticize. I'd suggest to just stick with the theories that researchers have come up with and improve upon them.
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