I'll have to try and find the article, this was years ago, but there was a study about people just tapping their brakes lightly that would cause the person behind to do the same, a little longer, etc. etc. that would cause a big traffic jam over time. The study calculated some figure that showed if people just kept their distance up to the person in front, and instead of lightly tapping the brake as a reaction to a merge, and just let the car idle a bit to slowly decelerate, you could reduce traffic slows / jams by a lot. This seems more reasonable than the solutions presented by this article, don't let people merge.. really?
How traffic actually works
21–30 of 186 posts
Re: How traffic actually works
#22Earlier quoted context omitted.
Except I don't consider it an asshole move because as OP points out, I'm making the best use of the road ahead (while allowing fewer people to merge ahead of me) Which solves nothing but to piss off everyone else behind you who has waited because ultimately someone will let you merge in (which they flat out shouldn't) and said behavior will only encourage others to do so in the future which inevitably will piss off e…
Nobody is forcing you to stay in the congested lane. It was your choice and you have no reason to think everyone else has to do the same. If it's a legal lane, then drive in it.
Its a legal lane to no where. By using it you're then relying on the good graces of one of those chumps you just passed. They don't need to let you back in. They're in the legal lane to somewhere, you just got no where really quickly.
Re: How traffic actually works
#23There are cases where leaving a greater-than-normal lane spacing makes sense, in the interest of safety. Safety is something utterly ignored in the fascinating analysis in this article. For example, if I'm in a left lane buzzing along at wide-open freeway speeds and the right lane next to me is congested and backed up and not moving, I leave more than normal spacing in front of me. Why? Because it's very likely that someone stuck in the right lane is going to dart out in front of me or the driver in front of me, and very likely that I'm going to need to make a very sudden stop. It's just unsafe to cruise along at 75 mph next to hundreds of cars that are looking for an opportunity to jump in front of me.
The prisoner's dilemma also applies to this. Behavior that is "optimal" for a single individual in terms of getting to destination is not what's optimal for the collective in terms of safety. And optimal behavior for getting to destination is not the optimal behavior for safety or lower stress driving, either.
Re: How traffic actually works
#24Earlier quoted context omitted.
Except I don't consider it an asshole move because as OP points out, I'm making the best use of the road ahead (while allowing fewer people to merge ahead of me) Which solves nothing but to piss off everyone else behind you who has waited because ultimately someone will let you merge in (which they flat out shouldn't) and said behavior will only encourage others to do so in the future which inevitably will piss off e…
Nobody is forcing you to stay in the congested lane. It was your choice and you have no reason to think everyone else has to do the same. If it's a legal lane, then drive in it.
That's fine if you can safely merge into the exit lane without slowing down traffic in the non-exit lane.
Here's when it's not OK: cars in the exit lane are traveling at 2mph. You drive up next to the line, slow down from 55mph to 2mph and wait with your blinker on for someone to let you in. Now you've slowed a second 55mph lane down to 2mph, blocking thru traffic and creating a dangerous stoppage in the non-exit lane.
Seriously, don't do this.
Re: How traffic actually works
#25Thanks for explaining this for us. What is missing from this compared to what I see on the roads is trucks. The truckers always leave large gaps and it's a sure bet that jerks will cut in front of these rigs. I don't think the trucks are leaving that much space to "smooth out" the traffic but it's more a matter of safety and efficiency (saves fuel) when all the nimble passenger vehicles are stop and go and zipping al…
If ever I hit a jam on the motorway, I always pull to the left lane (UK), join the trucks, and imitate their driving style. Almost always, over the length of the jam, I beat my neighbours in the middle lane without doing any lane hopping.
Re: How traffic actually works
#26There are cases where leaving a greater-than-normal lane spacing makes sense, in the interest of safety. Safety is something utterly ignored in the fascinating analysis in this article. For example, if I'm in a left lane buzzing along at wide-open freeway speeds and the right lane next to me is congested and backed up and not moving, I leave more than normal spacing in front of me. Why? Because it's very likely that…
I'd argue that safety directly translates into speed as well, as a single accident can shut down 1-all lanes of the freeway and result in several hours of delay for the parties involved. So even being selfish you'd have reason to err on safety's side
Re: How traffic actually works
#27Earlier quoted context omitted.
This. I've studied traffic extensively and if you ever wonder how it works, it is actually quite similar to any other network. Imagine road traffic is the same as traffic through your servers. There are hard bottlenecks at various points, but in practice what matters is planning for variability. Real-life situations like someone cutting you off, people rubber-necking, the natural commute tendencies etc tend to be muc…
re spinning up a new lane: the A38-M Aston Expressway into Birmingham, UK dynamically multiplexes its lanes together into variable width channels depending on the required upstream/downstream bandwidth :) - http://i3.birminghammail.co.uk/incoming/article1294911.ece/A...
That is sort of terrifying but also quite cool
Re: How traffic actually works
#28There are cases where leaving a greater-than-normal lane spacing makes sense, in the interest of safety. Safety is something utterly ignored in the fascinating analysis in this article. For example, if I'm in a left lane buzzing along at wide-open freeway speeds and the right lane next to me is congested and backed up and not moving, I leave more than normal spacing in front of me. Why? Because it's very likely that…
You probably shouldn't be cruising at 75 mph next to a lane of stopped traffic regardless. Leaving more space between you and the next car wouldn't seem to make that practice significantly safer.
I agree that the optimal behavior isn't universal though. One example I'd cite is that I always leave more space when the vehicle in front me is so big that I can't see what's in front of it since that limits my reaction time to what that one vehicle is doing rather than what's going on further ahead.
Re: How traffic actually works
#29That was the clearest explanation of traffic I've come across. I'm inclined to buy into it (often it seems no one knows what they're talking about when it comes to traffic). It also runs counter to what is commonly said about traffic jams. Most people focus on restoring smooth flow by doing things such as driving really slow to create space in front of you. This guy makes the case that "flow" is not really the import…
Part of the problem is a lack of established convention. When a theme park opens its gates in the morning, we expect a large crowd to jostle in through a constricted entrance like a funnel. However, when we queue up at the bank, if the line extends past the cordon, nobody runs up to that point and stands shoulder to shoulder with other patrons; we maintain a single file.
Which of these rules applies to cars merging? There isn't a set standard, so people invent their own and perceive their rule is universally understood.
Re: How traffic actually works
#30The 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. I've studied traffic extensively and if you ever wonder how it works, it is actually quite similar to any other network. Imagine road traffic is the same as traffic through your servers. There are hard bottlenecks at various points, but in practice what matters is planning for variability. Real-life situations like someone cutting you off, people rubber-necking, the natural commute tendencies etc tend to be muc…
So the older/well circulated article that this author complains about would be describing Van Jacobson's algorithm?
Am I missing something about what the author is saying about the empirical data?
The stark uniformity of the empirical data up to the congestion threshold compared to the wild variance in heavier traffic is exactly the point of the older article this author is critiquing. Of course congestion happens when you approach capacity. This article is rejecting the original's explanation of that variance, without offering any new explanation.