9 ms·

The Physics Behind Traffic Jams

256 points by netvarun 13y ago

caw 13y ago
Interesting blog article. I've always found it strange that when school is out, traffic is like 30-50% better. This effect is the best I can think of, because I wouldn't think there's a lot of people directly impacted by the school schedule. Elementary, middle and high schools all start and end at different times, and there's people directly employed by all of those schools, and certainly some parents who pick up and drop their kids off, but still it doesn't seem like that many people compared to how much better the traffic gets. So maybe this article is right, you take a few people off the road and the merging madness, and everything becomes better.
- codfrantic 13y ago
  I notice the same thing, Even in one week holidays where only the elementary schools are closed the traffic is much lighter. I expect this because a lot of working parents take this week off too to be with the kids, probably a 10-15% drop of traffic means that traffic is a lot easier.
matiasb 13y ago
interesting!
- vladoh 13y ago
  This reminds me of an interesting traffic simulation applet, where you can control things like aggressiveness of the drivers, traffic density etc. and observe the traffic jam that happens. http://www.carbibles.com/trafficmicrosimulation.html http://www.carbibles.com/trafficmicrosimulation.html
ChrisNorstrom 13y ago
Yeah, Traffic Waves. There's no cure. They've been studied, documented, they have many causes but there's no way to get rid of them unless all the cars on the highway are autonomous and self correcting. Once a highway increases past 2 lanes they are inevitable as people from the far left lanes have to merge right to get to their exit and the 2 right lanes than can normally hold 20 cars with a 1 car space in between all of them now have to cope with 35 cars. The cars in the left lane can't merge in time to get to their exit so the far left lanes start slowing down as well. There are a LOT of causes, from bunching (cars driving too close together) to pattern breaking (cars slowing down to look a pulled over cop), to merging, to accidents, to bottlenecks, to over-crowded exits, etc... The only way to provide some relief is for ALL drivers to travel in groups/packs with large gaps in between the groups/packs. The gaps can obsorb slow downs.
- covercash 13y ago
  >The only way to provide some relief is for ALL drivers to travel in groups/packs with large gaps in between the groups/packs. The gaps can obsorb slow downs. Whenever I'm stuck in Philadelphia traffic I try to do this and it seems to make a difference. I've even thought about getting a bunch of friends to all get on at different exits and do it simultaneously. The end goal being official "pace cars" coordinated by a central command center to alleviate stop & go traffic and keep everyone cruising at a constant speed. Needless to say, my mind wanders a lot when I'm stuck in traffic!
  - refurb 13y ago
    I've actually done something similar. When in bad traffic i purposely drive so that i leave a large gap between me and the car ahead of me. I basically drive so that i have to do minimal accelerating/braking. Likely just a coincidnce, but it does seem to improve flow.
    - covercash 13y ago
      Are you located in/around Philly? If so, I'd be interested in coordinating something on 476 or 422 one afternoon.
      - refurb 13y ago
        Nope! Bay area (which btw, does not have bad traffic relatively speaking; I've been in traffic jams in the NE and they are way worse, same with LA).
    - sk5t 13y ago
      I do this when stuck in a jam with a manual transmission car. I'll just leave it in first and idle along at ~5 mph... this is slower than the momentary maximum ~15 mph "rubber band" speed but certainly feels like it smooths things out in the long term, and is a lot easier on my clutch foot.
    - priscillasj 13y ago
Stark2 13y ago
On the freeway system in LA, a lot of the jams are caused by slow drivers in the passing lanes. Most the time, when there's a clump of cars and empty space ahead of them, it's one or two slow drivers blocking the passing lanes.
aba_sababa 13y ago
This is awesome. The problem is that no individual agent is incentivized to drive slower. I wonder if it'd be worth it to hire "stir-the-pot cars" whose job it is to drive slowly during rush hour and ease jams. Kind of like dietary fiber for the road. Hey, doesn't Uber have a whole fleet of cars in cities around the world? It would be a cool $&@! project for them to be the all-wondrous curers of traffic.
- rallison 13y ago
  One could argue that there is an incentive. If you drive a little slower and leave a large gap in front, you get to avoid always being on watch for the guy in front of you slamming on their brakes. This can be a whole lot less stressful, which is incentive itself.
- rosser 13y ago
  I think the problem is less one of incentive than it is one of awareness. If more people knew about — and actually understood — anti-traffic, more people would employ it. I don't know where the inflection point is, but I'd bet you don't even need all that many people engaging in anti-traffic behavior before it has an appreciable impact, either.
- dbecker 13y ago
  The Colorado Department of Transportation does essentially this with "pace cars" at high traffic times coming back from the ski areas.
dirkgently 13y ago
I have been experimenting a bit whenever I am stuck in the traffic. The goal is not to come to a complete stop. So, in order to do that, I keep long enough gap in front of me while the traffic is crawling, and keep a low speed such that I do not get too close to the car in front (in which case, I have to come to a complete stop). Just by doing that, the car behind me can also just follow me at the same speed without coming to a complete halt. I just hate sitting still on the highway. This game keeps me entertained while also helping a few cars (if not all) behind me. The best place to see this effect is in a tunnel (say, Holland tunnel, where switching lane is not allowed). Just one car maintaining a low speed with enough space in the front can make the whole lane flowing so easily. I just don't understand people who would accelerate and the brake, and repeat this until they are out of the traffic. Not only you are causing yourself a lot of anguish, you are also not helping others, nor your car.
- Afforess 13y ago
  >I just don't understand people who would accelerate and the brake, and repeat this until they are out of the traffic. Not only you are causing yourself a lot of anguish, you are also not helping others, nor your car. I don't either. I developed the same strategy as you describe accidently in an effort to conserve fuel. Braking is effectively converting your precious gasoline into heat/sound/wear-on-parts. It's best to never have to break. I realize in practice that's not achievable, but there are many cases where a little foresight can mean just not accelerating and expecting stops earlier, and can give you a ~3-5mpg increase.
- enraged_camel 13y ago
  >>I just don't understand people who would accelerate and the brake, and repeat this until they are out of the traffic. Not only you are causing yourself a lot of anguish, you are also not helping others, nor your car. Accelerating and braking is also a fantastic way to waste gas.
- freework 13y ago
  Most people drive using the least amount of attention as possible to the road. The typical person behind the wheel is thinking more about their life's problems than they are thinking about the flow of traffic around them. When I'm driving to a place I've never been before. My attention is mainly on my GPS screen, not the flow of traffic ahead of me. When I'm on my daily commute, I notice the traffic patterns because that drive is boring and there is nothing else to think about when driving.
AndrewKemendo 13y ago
Some years ago (2008) research (1) demonstrated that traffic jams were chaotic dynamical systems and given a certain traffic density would be inevitable based on the variability of drivers. Here is a video demonstrating as such: http://www.youtube.com/watch?v=7wm-pZp_mi0 http://www.youtube.com/watch?v=7wm-pZp_mi0 I always found this fascinating. My hope is that the driverless car idea will take off in earnest and normalize the variability between drivers, making for a much more rational/logical commute. 1: http://iopscience.iop.org/1367-2630/10/3/033001/fulltext/ http://iopscience.iop.org/1367-2630/10/3/033001/fulltext/
- seanp2k2 13y ago
  The problem with driverless cars is that not everyone will switch to driverless cars overnight, so the driverless cars will have to deal with drivers. Ever had your GPS tell you to get in the wrong lane? I'd love to see how well a Google self-driving car gets on trying to get over 4 lanes in a mile in gridlock traffic. I live in the bay area, and you only ever see the self-driving cars out when traffic is very light. It'll probably be a "better cruise control" long before we have cars that we can get into, program a destination, and sit back while the car takes us there. It's a nice dream, but it seems 10+ years from being viable.
  - derekp7 13y ago
    For the "better cruise control" aspect, I can envision the user interface giving the drive the illusion of driving in a rut in the road. So that when the car drifts to one of the lane edges, there would be a slight tug on the steering wheel similar to what you would feel if the road was cupped -- but something you can easily overcome if you intend to.
socillion 13y ago
Original copy at http://trafficwaves.org/ http://trafficwaves.org/ A video from there, omitted from OP: https://www.youtube.com/watch?v=iGFqfTCL2fs https://www.youtube.com/watch?v=iGFqfTCL2fs OP is a cut-down version of this site, which has been up for a decade or two. I'm curious if it's a legitimate copy.
dirkgently 13y ago
A related Japanese experiment on the Human factor of traffic jam - https://www.youtube.com/watch?v=Suugn-p5C1M https://www.youtube.com/watch?v=Suugn-p5C1M
rallison 13y ago
If you enjoy this sort of stuff, the book Traffic: Why We Drive the Way We Do (and What It Says About Us) by Tom Vanderbilt[1] is an enjoyable read. He covers traffic waves and a lot more. [1] http://www.amazon.com/Traffic-Drive-What-Says-About/dp/0307277194 http://www.amazon.com/Traffic-Drive-What-Says-About/dp/03072...
EGreg 13y ago
I am reminded of this: http://www.technologyreview.com/view/425435/in-car-algorithm-could-rapidly-dissolve-traffic-jams/ http://www.technologyreview.com/view/425435/in-car-algorithm...
teuobk 13y ago
Contrary to one of the recommendations in the article, the Minnesota Department of Transportation recommends against merging early, and instead has made a large public-education effort (including signs at merge points) to encourage zipper merging: http://www.dot.state.mn.us/zippermerge/ http://www.dot.state.mn.us/zippermerge/ More discussion: http://www.drmomentum.com/aces/archives/003800.html http://www.drmomentum.com/aces/archives/003800.html
- saosebastiao 13y ago
  Their research is fundamentally flawed...and it is rooted in an fruitless desire to optimize something that is physically unoptimizable. There is no sand-arranging possibility that can cause the falling-rate of sand in an hourglass to change significantly.
  - seanmcdirmid 13y ago
    Merging later encourages better utilization of road capacity and eliminates bottlenecks further away from the overloaded resource. It's quite simple really, in this case the polite behavior is wrong, and if everyone would just be greedy, the behavior would no longer be impolite and would be more optimal (source, I live in china, this really works better than the alternative, we have plenty of overloaded resources).
    - saosebastiao 13y ago
      Every advocate always has their pet theory as to why their method works better than others. They also have "evidence" which is either completely anecdotal or does not control for even the most obvious of factors (such as rate of queue arrival or average speed in the constrained resource). Simply put, they are all wrong. A bottleneck is a bottleneck and there is no fairy dust magic queueing technique that works better than another. At best, some techniques might have a behavioral advantage...but I stress again, they are all inconsequential. We are talking tens of seconds of time savings at best.
      - 13y ago
chrismealy 13y ago
I saw William Beaty's zen traffic warrior video years ago, and I don't know if it works, but it sure makes me more relaxed when I'm driving.
deleted 13y ago
[deleted]
clarky07 13y ago
reminds me of an experiment by some college kids in atlanta - http://www.youtube.com/watch?v=OoETMCosULQ http://www.youtube.com/watch?v=OoETMCosULQ
tempestn 13y ago
Can't do this for traffic waves, but it would appear the ideal solution to merge slowdowns is to have different speed limits before and after the merge. Regardless of anything else, the flow rate before and after a merge must be the same. Ideally you want the flow rate after the merge to be approximately one car every 2.5 seconds, with those cars traveling at the speed limit. (As opposed to the usual situation where post-merge traffic accelerates from a near stop, causing large, unnecessary spaces to form.) One way to achieve this is to have pre-merge traffic leave twice the space, but it's unlikely there are enough traffic-flow vigilantes out there to achieve that, if such a thing would even be desirable. Much easier is to keep the same time spacing between cars, but to have pre-merge traffic travel at half the speed. Traffic approaches the merge in two lanes, traveling at 50 km/h. The speed limit increases to 100 km/h, then immediately afterward the traffic merges. Speeding up from 50 to 100 naturally opens spaces, and traffic merges painlessly. There is no reason for a slowdown to occur, so no self-perpetuating gridlock. Of course, the slower speed limit is only useful when the road is filled to capacity; otherwise it would be inefficient. So for most roads you would want this limit to vary based on time of day (or even dynamically based on traffic volume, but obviously that would only be useful/necessary in extreme cases).
mappum 13y ago
I found the idea that one person can make a huge difference really interesting, I will have to start experimenting with this myself. All the roads OP wrote about are where I drive, but the Lynnwood ramp he talked about recently got expanded. This also makes me want to make some sort of simple traffic simulator to do experiments like this, does anyone know if any already exist?
notmarkus 13y ago
The problem with leaving a gap is that, as soon as it's a few car-lengths long, people in the adjacent lane(s) notice that there's a gap and quickly cut into your lane to fill it, because it moves them a car-length or two forward. In order to do this, they have to cut in front of you, speed up quickly, and brake quickly. And you're left in the same position that you were in before you made the gap -- plus one extra car. I try to do this all the time and it's frustrating because it's completely impossible. As soon as a vacuum exists, drivers rush to fill it.
- ChuckMcM 13y ago
  So its interesting to watch the traffic around when this happens. It actually smooths out the flow "behind" you because the folks who cut in front eased up pressure behind them. The tail gater issue is real though so if you're going to do this it is best to do it in the right lane rather than one of the inner lanes.
  - timthorn 13y ago
    My experience has been that the "slow lane" is usually significantly faster through a jam, probably because of the number of lorries practicing smooth driving.
  - timthorn 13y ago
    My experience has been that the "slow lane" is usually significantly faster through a jam, probably because of the number of lorries practicing smooth driving.
freework 13y ago
The solution to traffic jams is to have a dynamically calculated speed limit based on the density of the traffic flowing through it. A car going 60mph down the highway needs 50 feet in front and 50 feet in back between it and the other cars (for braking distance). When that same car is going 20 mph, you only need 10 feet in front and back. Therefore, to support more cars, speed needs to slow down. You could have a device that counts the amount of cars entering the highway, and then an algorithm could assign a speed limit for a section of the highway. In the middle of the nigh, theres no one else on the road, so the speed limit will be very high. During rush hour the speed limit could be as low as 15mph. This would make merging easier since you're going slower. You wouldn't think that lowering speed limits would easy traffic congestion, but it would. Its a counter-intuitive, so it will never be implemented anywhere.
- pmenage 13y ago
  It's already implemented on the M25, the orbital motorway around London. It gets used quite frequently to slow commuter traffic down from a limit of 70mph to as low as 40. There's a particular incentive there because being a loop a bad traffic jam could (theoretically - I'm not sure it's ever happened) stretch so far that its head and tail collide. Plus, of course, the fact that the M25 was demonically planned in the shape of the mystic sigil Odegra, from the alphabet of the Black Priesthood of Ancient Mu.
  - lostlogin 13y ago
    It's done in central Auckland too.
- ygra 13y ago
  Many German motorways use that system and have dynamic speed limits based on the current traffic situation. The downside is that most people think »Why the hell should I drive 100 now when I can still drive 120?«, so depending on the mindset of the drivers this may or may not work. I rarely see those speed limits followed or enforced.
- ronaldx 13y ago
  Variable speed limits are well implemented on UK motorways. One thing I find interesting is that, as a traveller, it's completely impossible to fathom what's going on. Because the signs are on in apparently free-flowing traffic, it's really not clear whether the signs are providing any use or are just still turned on from a earlier occasion.
afterburner 13y ago
A shame "rubberneckers" were mentioned (even if in passing); it always bothers me when "rubberneckers" are blamed for a slowdown, despite that it may simply be the long-term wave slow-down after the incident (as also discussed in the article). The reason it bothers me, especially when it's mentioned in a traffic report, is it gives everyone a little easy road rage "blame the bad driver" excuse when everyone just needs to chill out and realize this will only cause a few minutes delay at worst. It's also futile to try to "train" everyone to overcome these little wave effects. All you're going to do is give some people an excuse to rage at others about their "inefficient" driving. Just keep your distance, follow the rules of the road, and put on some good music/audiobook/podcast/etc. You will get there eventually, and one day better self-driving cars or mass transit will make this frustration moot. (Note that even if self-driving cars aren't specifically programmed to solve the wave effect, it won't matter because you'll be too busy watching TV or reading to give a damn. I'm all for efficiency, but having commuted by car for years, it's not about these little things anyways, it's the sheer time spent that is the worst thing (and damaging on a personal level), and traffic accidents truly do block traffic anyways.)
- jakejake 13y ago
  I think it's easy to call everybody rubber-neckers, but in reality when you pass a big mess of police lights or anybody stopped on the side of the road, I consider it a bit of a courtesy and safety to slow it down a little and, if possible, merge into a lane so you don't do a "fly by" at full speed with somebody standing at the side of the road.
- vacri 13y ago
  It's entirely too human to have spent 20 minutes in a jam to finally get to the bottleneck, then spend all of 5 seconds seeing what all the fuss was. It'd be nice if folks didn't do this, but they're not going to stop en masse.
mortehu 13y ago
My heuristic when trying to help get rid of a traffic jam is this: > Maintain a higher minimum speed (and the same or higher average speed) than the car in front of you. The only reason why traffic jams ever disappear is that people are doing this. Most of the time I guess the true root cause is that incoming traffic is dissipating, though.
platz 13y ago
I remember some sort of experiment in Colorado in which state police formed a line of cars at intervals forcing everyone to drive the same speed, and thus was able to eliminate the daily blockages in that experiment.
adacosta 13y ago
I usually try to avoid hitting the brake as much as possible in order to maintain the most uniform speed I can. This is due to a selfish, lazy motivation, because I don't want to rapidly alternate between gas and brake. I think there is also a psychological component to seeing bright red brake lights. I want to say it creates a reactive, and often overly reactive response. I imagine lifting a foot off the gas pedal often creates sufficient deceleration without the alarm caused by hitting the brake pedal but many people don't drive this way. Maybe we should have two shades, or colors, or a full gradient to indicate level of braking? What if a brake light could indicate current speed?
networked 13y ago
The article shows what looks like a time-continuous microscopic traffic flow model ("microscopic" means that the model accounts for individual cars as opposed to fluid-like "traffic streams"). There also exist cellular automaton-based models like the two-dimensional Biham–Middleton–Levine model [1] or the one-dimensional rule 184 [2] that can also show fascinating behavior but are much easier to program a computer simulation of and to alter (say, introduce different kinds of vehicles to). Check out the videos on the Wikipedia page to which I've linked, especially [3], to see what I mean. In those videos the blue dots are trying to get from the top to the bottom while the red ones are trying to go from the left edge to the right edge of an "intersection". [1] https://en.wikipedia.org/wiki/Biham%E2%80%93Middleton%E2%80%93Levine_traffic_model https://en.wikipedia.org/wiki/Biham%E2%80%93Middleton%E2%80%... [2] https://www.wolframalpha.com/input/?i=rule+184 https://www.wolframalpha.com/input/?i=rule+184 [3] https://upload.wikimedia.org/wikipedia/commons/1/18/Biham-Middleton-Levine_traffic_model_self-organized_to_a_periodic_intermediate_phase.ogv https://upload.wikimedia.org/wikipedia/commons/1/18/Biham-Mi...
brownbat 13y ago
Jams spontaneously occur after a certain road density is reached. The sadistic side of me wishes they'd just close entrances to the highway whenever it's dangerously full.
makeramen 13y ago
This is really interesting. I wonder if the existing California Highway Patrol practice of swerving around the highway[1] to slow down traffic can be used to create these "anti-traffic" gaps during rush hour? [1] http://articles.latimes.com/1996-08-12/local/me-33464_1_traffic-enforcement http://articles.latimes.com/1996-08-12/local/me-33464_1_traf...
- lewispb 13y ago
  Near where I live in England we have managed motorways which employ electronic displays and enforce the speed limit with speed cameras. http://en.m.wikipedia.org/wiki/Managed_motorways_in_the_United_Kingdom http://en.m.wikipedia.org/wiki/Managed_motorways_in_the_Unit...
rheide 13y ago
This is the prisoner's dilemma. If you slow down and drive smoothly, and everyone else does too, then everyone benefits greatly. But if you cut in front of one of the smooth drivers, which you can since he's leaving lots of space, you benefit personally by gaining a car length while inconveniencing everyone else in that particular lane. Well, at least until the guy behind you has smoothed out the difference. Human nature makes smoothing out traffic an improbable solution.
Too 13y ago
It's the same as when approaching a red light or any other intersection. If you drive all the way up and make a full stop you will have to accelerate from 0 once you get green. If you slow down when you see the red you can be able to roll into the intersection with speed just as the light switches to green effectively giving you a 30km/h headstart or more. You leave the intersection faster and you save gas by not accelerating. I don't understand why more people don't do this very simple move. The tricky part is timing the switch perfectly which is almost impossible, instead you should just slow down more and more and more and try to never ever fully stop the car fully.
- dsego 13y ago
  I honestly try this every time and slow down before nearing the intersection. But often there are assholes who overtake and come in front and fill up the road ahead, making me brake and come to a stop as well.
- 3minus1 13y ago
  > just as the light switches to green effectively giving you a 30km/h headstart or more Please be careful with this. If you immediately occupy an intersection after a light turns green there's a chance you'll get blindsided when another car decides to run a red.
sly010 13y ago
Does this mean it's actually possible to improve traffic by introducing extra tempo setter cars whose only job is to smooth traffic?
mooze 13y ago
There's a whole chapter on traffic jams in the book Critical Mass. From what I remember, innocuous things like a single driver slowing down can cause massive jams due to the natural 'physics' of traffic.
frogpelt 13y ago
The merging solution is oversimplified. Leaving enough space for another car in front of you sounds easy. But in reality, if 1,000 cars each add 2 car lengths in front of them you've added 40,000 feet to the length of the slow down. Yep, 7.5 miles. If it was feasible, we could also stop at red lights with 3 or 4 car lengths between each car and when the light turned green everyone could go at the same time. There isn't space on the road for this type of behavior.
jdleesmiller 13y ago
There's a nice simulation of these physics here: http://www.traffic-simulation.de http://www.traffic-simulation.de The jams seem pretty robust, unless you turn down the input flow -- a bit like real life!
jasallen 13y ago
"ON THE RIGHT >>>>> DRIVERS WITH UNUSUAL BEHAVIOR: THEY ENCOURAGE OTHERS TO MERGE AHEAD OF THEM, AND THEY TEND TO MAINTAIN LARGE SPACES AHEAD, EVEN IF TRAFFIC SLOWS TO A CRAWL. MERGING IS EASY. SEE HOW MUCH FASTER THEY GO?" This is misleading 1)The actual throughput of cars through the constriction even in the animation is only slightly faster despite 'apparent' better speeds. 2)The animation does not account for drivers re-assuming their previous following distance. Regardless of whether your 'comfort' distance is half car-length or 5 car lengths, you will eventually resume it. Leading to a slowdown. The advice, and animation seems to assume both that we've merged (onto the highway in the first place) at a rate that can absorb those driving distances without additional slow-down and that we won't resume our previous driving distance (after merging past the constriction). In short, its moved the problem and then shown a window into the part that was improved. *edit: added parenthetics to improve clarity
seanp2k2 13y ago
>"It was dusk, the headlights were on, and I was going down a long hill to the bridges. I had a view of miles of highway behind me. In the other lane I could see maybe five of the traffic stop-waves. But in the lane behind me, for miles, TOTALLY UNIFORM DISTRIBUTION. I hadn't realized it, but by driving at the average speed, my car had been "eating" traffic waves. Everyone ahead of me was caught in the stop/go cycle, while everyone behind me was forced to go at a nice smooth 35MPH or so. My single tiny car had erased miles and miles of stop-and-go traffic. Just one single "lubricant atom" had a profound effect on the turbulent particle flow within the "tube."" When I try this, most other people have no idea what I'm doing and/or are stupidly greedy and go "OMG A GAP" and rush into it. I'll also typically have people behind me honking / flashing their headlights at me, as they're equally clueless. I've had one dude and his wife, in a Harley Davidson edition F150 actually roll down their window and scream at me for "not knowing how to drive". I drive a 6spd stick too, so the stop/go is even more painful. I try to be that "lubricating atom" both for my sanity and to ease the jam, but the collective inability of other drivers to think beyond "OMG MAKE AS MUCH PROGRESS AS SOON AS I CAN" greatly inhibits my efforts. TL;DR traffic jams are caused because people are greedy and short-sighted in their greed. It's not really different from all of the other big problems with humanity.
- deleted 13y ago
  [deleted]
- jaredmcateer 13y ago
  I experienced this as well but you know what, my driving experience is much less stressful on the whole and it's kind of amusing seeing people try to fill that gap by speeding past you only to slam on the brakes as second later.
- icambron 13y ago
  I have a different theory on why people jump into gaps: they're bored. Traffic jams are really dull, and the illusion of progress is much more entertaining. So not really greed. And it's more ignorance/self-centeredness than short-sightedness; they haven't thought of the jam as a systemic problem to which they're contributing.
- 13y ago
seanp2k2 13y ago
Even better solution to traffic: develop real high-speed rail in the US, live closer to where you work / need to be (stop suburbs / sprawl), ride bikes or even just motorcycles / mopeds in California where filtering is legal, or walk. This has a lot of other nice first-order benefits like real communities, decreased pollution, less time wasted commuting, and tons of second-order benefits.
pbnjay 13y ago
Someone at Waze should get on this. Send a small notification to Waze users that there's a jam ahead, and to slow down by 10mph to help alleviate it! It's a simple solution and might even work since Waze users are already a "community" of drivers in the sense that they're looking out for each other and not necessarily just themselves.
sigil 13y ago
If you're interested in the physics of it, there's a PDE that explains these backwards propagating density shockwaves (aka traffic jams). http://en.wikipedia.org/wiki/Burgers'_equation http://en.wikipedia.org/wiki/Burgers'_equation
mwexler 13y ago
This appears to be a prettier version of William Beaty's work at http://trafficwaves.org/ http://trafficwaves.org/ which is well worth the read. I send this link out multiple times a year to friends, because it advocates (and shows some proof for) some simple driving changes that can substantially reduce traffic: Leave space ahead of you, and let folks cut in if they want. Given the chaotic pattern of traffic and drivers, these simple habits appear to reduce (but never eliminate) traffic jams.
- manojlds 13y ago
  Just to be clear, both are by the same person.
  - mwexler 13y ago
    Indeed, the article is credited to him, thanks for pointing that out (missed that!). But the original posted site ("smartmotorist") didn't seem to have any credits, so unclear if it's a rip-and-post or if Mr. Beaty was part of "smartmotorist". Regardless, I think Trafficwaves.org gives more info, so wanted to share.
- CompelTechnic 13y ago
  I love Beaty's stuff. I've tracked his amasci.com for a couple years now- although his updates are few and far between, they are often gems. He's a damn good modern day mad scientist.
WalterBright 13y ago
> My single tiny car had erased miles and miles of stop-and-go traffic. Just one single "lubricant atom" had a profound effect on the turbulent particle flow within the "tube". I did this in the 1970's. It gets rediscovered constantly.

256 points by netvarun 13y ago

caw 13y ago

Interesting blog article. I've always found it strange that when school is out, traffic is like 30-50% better. This effect is the best I can think of, because I wouldn't think there's a lot of people directly impacted by the school schedule. Elementary, middle and high schools all start and end at different times, and there's people directly employed by all of those schools, and certainly some parents who pick up and drop their kids off, but still it doesn't seem like that many people compared to how much better the traffic gets. So maybe this article is right, you take a few people off the road and the merging madness, and everything becomes better.

codfrantic 13y ago
I notice the same thing, Even in one week holidays where only the elementary schools are closed the traffic is much lighter. I expect this because a lot of working parents take this week off too to be with the kids, probably a 10-15% drop of traffic means that traffic is a lot easier.

matiasb 13y ago

interesting!

vladoh 13y ago
This reminds me of an interesting traffic simulation applet, where you can control things like aggressiveness of the drivers, traffic density etc. and observe the traffic jam that happens. http://www.carbibles.com/trafficmicrosimulation.html http://www.carbibles.com/trafficmicrosimulation.html

ChrisNorstrom 13y ago

Yeah, Traffic Waves. There's no cure. They've been studied, documented, they have many causes but there's no way to get rid of them unless all the cars on the highway are autonomous and self correcting. Once a highway increases past 2 lanes they are inevitable as people from the far left lanes have to merge right to get to their exit and the 2 right lanes than can normally hold 20 cars with a 1 car space in between all of them now have to cope with 35 cars. The cars in the left lane can't merge in time to get to their exit so the far left lanes start slowing down as well. There are a LOT of causes, from bunching (cars driving too close together) to pattern breaking (cars slowing down to look a pulled over cop), to merging, to accidents, to bottlenecks, to over-crowded exits, etc... The only way to provide some relief is for ALL drivers to travel in groups/packs with large gaps in between the groups/packs. The gaps can obsorb slow downs.

covercash 13y ago
>The only way to provide some relief is for ALL drivers to travel in groups/packs with large gaps in between the groups/packs. The gaps can obsorb slow downs. Whenever I'm stuck in Philadelphia traffic I try to do this and it seems to make a difference. I've even thought about getting a bunch of friends to all get on at different exits and do it simultaneously. The end goal being official "pace cars" coordinated by a central command center to alleviate stop & go traffic and keep everyone cruising at a constant speed. Needless to say, my mind wanders a lot when I'm stuck in traffic!
- refurb 13y ago
  I've actually done something similar. When in bad traffic i purposely drive so that i leave a large gap between me and the car ahead of me. I basically drive so that i have to do minimal accelerating/braking. Likely just a coincidnce, but it does seem to improve flow.
  - covercash 13y ago
    Are you located in/around Philly? If so, I'd be interested in coordinating something on 476 or 422 one afternoon.
    - refurb 13y ago
      Nope! Bay area (which btw, does not have bad traffic relatively speaking; I've been in traffic jams in the NE and they are way worse, same with LA).
  - sk5t 13y ago
    I do this when stuck in a jam with a manual transmission car. I'll just leave it in first and idle along at ~5 mph... this is slower than the momentary maximum ~15 mph "rubber band" speed but certainly feels like it smooths things out in the long term, and is a lot easier on my clutch foot.
  - priscillasj 13y ago

Stark2 13y ago

On the freeway system in LA, a lot of the jams are caused by slow drivers in the passing lanes. Most the time, when there's a clump of cars and empty space ahead of them, it's one or two slow drivers blocking the passing lanes.

aba_sababa 13y ago

This is awesome. The problem is that no individual agent is incentivized to drive slower. I wonder if it'd be worth it to hire "stir-the-pot cars" whose job it is to drive slowly during rush hour and ease jams. Kind of like dietary fiber for the road. Hey, doesn't Uber have a whole fleet of cars in cities around the world? It would be a cool $&@! project for them to be the all-wondrous curers of traffic.

rallison 13y ago
One could argue that there is an incentive. If you drive a little slower and leave a large gap in front, you get to avoid always being on watch for the guy in front of you slamming on their brakes. This can be a whole lot less stressful, which is incentive itself.
rosser 13y ago
I think the problem is less one of incentive than it is one of awareness. If more people knew about — and actually understood — anti-traffic, more people would employ it. I don't know where the inflection point is, but I'd bet you don't even need all that many people engaging in anti-traffic behavior before it has an appreciable impact, either.
dbecker 13y ago
The Colorado Department of Transportation does essentially this with "pace cars" at high traffic times coming back from the ski areas.

dirkgently 13y ago

I have been experimenting a bit whenever I am stuck in the traffic. The goal is not to come to a complete stop. So, in order to do that, I keep long enough gap in front of me while the traffic is crawling, and keep a low speed such that I do not get too close to the car in front (in which case, I have to come to a complete stop). Just by doing that, the car behind me can also just follow me at the same speed without coming to a complete halt. I just hate sitting still on the highway. This game keeps me entertained while also helping a few cars (if not all) behind me. The best place to see this effect is in a tunnel (say, Holland tunnel, where switching lane is not allowed). Just one car maintaining a low speed with enough space in the front can make the whole lane flowing so easily. I just don't understand people who would accelerate and the brake, and repeat this until they are out of the traffic. Not only you are causing yourself a lot of anguish, you are also not helping others, nor your car.

Afforess 13y ago
>I just don't understand people who would accelerate and the brake, and repeat this until they are out of the traffic. Not only you are causing yourself a lot of anguish, you are also not helping others, nor your car. I don't either. I developed the same strategy as you describe accidently in an effort to conserve fuel. Braking is effectively converting your precious gasoline into heat/sound/wear-on-parts. It's best to never have to break. I realize in practice that's not achievable, but there are many cases where a little foresight can mean just not accelerating and expecting stops earlier, and can give you a ~3-5mpg increase.
enraged_camel 13y ago
>>I just don't understand people who would accelerate and the brake, and repeat this until they are out of the traffic. Not only you are causing yourself a lot of anguish, you are also not helping others, nor your car. Accelerating and braking is also a fantastic way to waste gas.
freework 13y ago
Most people drive using the least amount of attention as possible to the road. The typical person behind the wheel is thinking more about their life's problems than they are thinking about the flow of traffic around them. When I'm driving to a place I've never been before. My attention is mainly on my GPS screen, not the flow of traffic ahead of me. When I'm on my daily commute, I notice the traffic patterns because that drive is boring and there is nothing else to think about when driving.

AndrewKemendo 13y ago

Some years ago (2008) research (1) demonstrated that traffic jams were chaotic dynamical systems and given a certain traffic density would be inevitable based on the variability of drivers. Here is a video demonstrating as such: http://www.youtube.com/watch?v=7wm-pZp_mi0 http://www.youtube.com/watch?v=7wm-pZp_mi0 I always found this fascinating. My hope is that the driverless car idea will take off in earnest and normalize the variability between drivers, making for a much more rational/logical commute. 1: http://iopscience.iop.org/1367-2630/10/3/033001/fulltext/ http://iopscience.iop.org/1367-2630/10/3/033001/fulltext/

seanp2k2 13y ago
The problem with driverless cars is that not everyone will switch to driverless cars overnight, so the driverless cars will have to deal with drivers. Ever had your GPS tell you to get in the wrong lane? I'd love to see how well a Google self-driving car gets on trying to get over 4 lanes in a mile in gridlock traffic. I live in the bay area, and you only ever see the self-driving cars out when traffic is very light. It'll probably be a "better cruise control" long before we have cars that we can get into, program a destination, and sit back while the car takes us there. It's a nice dream, but it seems 10+ years from being viable.
- derekp7 13y ago
  For the "better cruise control" aspect, I can envision the user interface giving the drive the illusion of driving in a rut in the road. So that when the car drifts to one of the lane edges, there would be a slight tug on the steering wheel similar to what you would feel if the road was cupped -- but something you can easily overcome if you intend to.

socillion 13y ago

Original copy at http://trafficwaves.org/ http://trafficwaves.org/ A video from there, omitted from OP: https://www.youtube.com/watch?v=iGFqfTCL2fs https://www.youtube.com/watch?v=iGFqfTCL2fs OP is a cut-down version of this site, which has been up for a decade or two. I'm curious if it's a legitimate copy.

dirkgently 13y ago

A related Japanese experiment on the Human factor of traffic jam - https://www.youtube.com/watch?v=Suugn-p5C1M https://www.youtube.com/watch?v=Suugn-p5C1M

rallison 13y ago

If you enjoy this sort of stuff, the book Traffic: Why We Drive the Way We Do (and What It Says About Us) by Tom Vanderbilt[1] is an enjoyable read. He covers traffic waves and a lot more. [1] http://www.amazon.com/Traffic-Drive-What-Says-About/dp/0307277194 http://www.amazon.com/Traffic-Drive-What-Says-About/dp/03072...

EGreg 13y ago

I am reminded of this: http://www.technologyreview.com/view/425435/in-car-algorithm-could-rapidly-dissolve-traffic-jams/ http://www.technologyreview.com/view/425435/in-car-algorithm...

teuobk 13y ago

Contrary to one of the recommendations in the article, the Minnesota Department of Transportation recommends against merging early, and instead has made a large public-education effort (including signs at merge points) to encourage zipper merging: http://www.dot.state.mn.us/zippermerge/ http://www.dot.state.mn.us/zippermerge/ More discussion: http://www.drmomentum.com/aces/archives/003800.html http://www.drmomentum.com/aces/archives/003800.html

saosebastiao 13y ago
Their research is fundamentally flawed...and it is rooted in an fruitless desire to optimize something that is physically unoptimizable. There is no sand-arranging possibility that can cause the falling-rate of sand in an hourglass to change significantly.
- seanmcdirmid 13y ago
  Merging later encourages better utilization of road capacity and eliminates bottlenecks further away from the overloaded resource. It's quite simple really, in this case the polite behavior is wrong, and if everyone would just be greedy, the behavior would no longer be impolite and would be more optimal (source, I live in china, this really works better than the alternative, we have plenty of overloaded resources).
  - saosebastiao 13y ago
    Every advocate always has their pet theory as to why their method works better than others. They also have "evidence" which is either completely anecdotal or does not control for even the most obvious of factors (such as rate of queue arrival or average speed in the constrained resource). Simply put, they are all wrong. A bottleneck is a bottleneck and there is no fairy dust magic queueing technique that works better than another. At best, some techniques might have a behavioral advantage...but I stress again, they are all inconsequential. We are talking tens of seconds of time savings at best.
    - 13y ago

chrismealy 13y ago

I saw William Beaty's zen traffic warrior video years ago, and I don't know if it works, but it sure makes me more relaxed when I'm driving.

deleted 13y ago

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clarky07 13y ago

reminds me of an experiment by some college kids in atlanta - http://www.youtube.com/watch?v=OoETMCosULQ http://www.youtube.com/watch?v=OoETMCosULQ

tempestn 13y ago

Can't do this for traffic waves, but it would appear the ideal solution to merge slowdowns is to have different speed limits before and after the merge. Regardless of anything else, the flow rate before and after a merge must be the same. Ideally you want the flow rate after the merge to be approximately one car every 2.5 seconds, with those cars traveling at the speed limit. (As opposed to the usual situation where post-merge traffic accelerates from a near stop, causing large, unnecessary spaces to form.) One way to achieve this is to have pre-merge traffic leave twice the space, but it's unlikely there are enough traffic-flow vigilantes out there to achieve that, if such a thing would even be desirable. Much easier is to keep the same time spacing between cars, but to have pre-merge traffic travel at half the speed. Traffic approaches the merge in two lanes, traveling at 50 km/h. The speed limit increases to 100 km/h, then immediately afterward the traffic merges. Speeding up from 50 to 100 naturally opens spaces, and traffic merges painlessly. There is no reason for a slowdown to occur, so no self-perpetuating gridlock. Of course, the slower speed limit is only useful when the road is filled to capacity; otherwise it would be inefficient. So for most roads you would want this limit to vary based on time of day (or even dynamically based on traffic volume, but obviously that would only be useful/necessary in extreme cases).

mappum 13y ago

I found the idea that one person can make a huge difference really interesting, I will have to start experimenting with this myself. All the roads OP wrote about are where I drive, but the Lynnwood ramp he talked about recently got expanded. This also makes me want to make some sort of simple traffic simulator to do experiments like this, does anyone know if any already exist?

notmarkus 13y ago

The problem with leaving a gap is that, as soon as it's a few car-lengths long, people in the adjacent lane(s) notice that there's a gap and quickly cut into your lane to fill it, because it moves them a car-length or two forward. In order to do this, they have to cut in front of you, speed up quickly, and brake quickly. And you're left in the same position that you were in before you made the gap -- plus one extra car. I try to do this all the time and it's frustrating because it's completely impossible. As soon as a vacuum exists, drivers rush to fill it.

ChuckMcM 13y ago
So its interesting to watch the traffic around when this happens. It actually smooths out the flow "behind" you because the folks who cut in front eased up pressure behind them. The tail gater issue is real though so if you're going to do this it is best to do it in the right lane rather than one of the inner lanes.
- timthorn 13y ago
  My experience has been that the "slow lane" is usually significantly faster through a jam, probably because of the number of lorries practicing smooth driving.
- timthorn 13y ago
  My experience has been that the "slow lane" is usually significantly faster through a jam, probably because of the number of lorries practicing smooth driving.

freework 13y ago

The solution to traffic jams is to have a dynamically calculated speed limit based on the density of the traffic flowing through it. A car going 60mph down the highway needs 50 feet in front and 50 feet in back between it and the other cars (for braking distance). When that same car is going 20 mph, you only need 10 feet in front and back. Therefore, to support more cars, speed needs to slow down. You could have a device that counts the amount of cars entering the highway, and then an algorithm could assign a speed limit for a section of the highway. In the middle of the nigh, theres no one else on the road, so the speed limit will be very high. During rush hour the speed limit could be as low as 15mph. This would make merging easier since you're going slower. You wouldn't think that lowering speed limits would easy traffic congestion, but it would. Its a counter-intuitive, so it will never be implemented anywhere.

pmenage 13y ago
It's already implemented on the M25, the orbital motorway around London. It gets used quite frequently to slow commuter traffic down from a limit of 70mph to as low as 40. There's a particular incentive there because being a loop a bad traffic jam could (theoretically - I'm not sure it's ever happened) stretch so far that its head and tail collide. Plus, of course, the fact that the M25 was demonically planned in the shape of the mystic sigil Odegra, from the alphabet of the Black Priesthood of Ancient Mu.
- lostlogin 13y ago
  It's done in central Auckland too.
ygra 13y ago
Many German motorways use that system and have dynamic speed limits based on the current traffic situation. The downside is that most people think »Why the hell should I drive 100 now when I can still drive 120?«, so depending on the mindset of the drivers this may or may not work. I rarely see those speed limits followed or enforced.
ronaldx 13y ago
Variable speed limits are well implemented on UK motorways. One thing I find interesting is that, as a traveller, it's completely impossible to fathom what's going on. Because the signs are on in apparently free-flowing traffic, it's really not clear whether the signs are providing any use or are just still turned on from a earlier occasion.

afterburner 13y ago

A shame "rubberneckers" were mentioned (even if in passing); it always bothers me when "rubberneckers" are blamed for a slowdown, despite that it may simply be the long-term wave slow-down after the incident (as also discussed in the article). The reason it bothers me, especially when it's mentioned in a traffic report, is it gives everyone a little easy road rage "blame the bad driver" excuse when everyone just needs to chill out and realize this will only cause a few minutes delay at worst. It's also futile to try to "train" everyone to overcome these little wave effects. All you're going to do is give some people an excuse to rage at others about their "inefficient" driving. Just keep your distance, follow the rules of the road, and put on some good music/audiobook/podcast/etc. You will get there eventually, and one day better self-driving cars or mass transit will make this frustration moot. (Note that even if self-driving cars aren't specifically programmed to solve the wave effect, it won't matter because you'll be too busy watching TV or reading to give a damn. I'm all for efficiency, but having commuted by car for years, it's not about these little things anyways, it's the sheer time spent that is the worst thing (and damaging on a personal level), and traffic accidents truly do block traffic anyways.)

jakejake 13y ago
I think it's easy to call everybody rubber-neckers, but in reality when you pass a big mess of police lights or anybody stopped on the side of the road, I consider it a bit of a courtesy and safety to slow it down a little and, if possible, merge into a lane so you don't do a "fly by" at full speed with somebody standing at the side of the road.
vacri 13y ago
It's entirely too human to have spent 20 minutes in a jam to finally get to the bottleneck, then spend all of 5 seconds seeing what all the fuss was. It'd be nice if folks didn't do this, but they're not going to stop en masse.

mortehu 13y ago

My heuristic when trying to help get rid of a traffic jam is this: > Maintain a higher minimum speed (and the same or higher average speed) than the car in front of you. The only reason why traffic jams ever disappear is that people are doing this. Most of the time I guess the true root cause is that incoming traffic is dissipating, though.

platz 13y ago

I remember some sort of experiment in Colorado in which state police formed a line of cars at intervals forcing everyone to drive the same speed, and thus was able to eliminate the daily blockages in that experiment.

adacosta 13y ago

I usually try to avoid hitting the brake as much as possible in order to maintain the most uniform speed I can. This is due to a selfish, lazy motivation, because I don't want to rapidly alternate between gas and brake. I think there is also a psychological component to seeing bright red brake lights. I want to say it creates a reactive, and often overly reactive response. I imagine lifting a foot off the gas pedal often creates sufficient deceleration without the alarm caused by hitting the brake pedal but many people don't drive this way. Maybe we should have two shades, or colors, or a full gradient to indicate level of braking? What if a brake light could indicate current speed?

networked 13y ago

The article shows what looks like a time-continuous microscopic traffic flow model ("microscopic" means that the model accounts for individual cars as opposed to fluid-like "traffic streams"). There also exist cellular automaton-based models like the two-dimensional Biham–Middleton–Levine model [1] or the one-dimensional rule 184 [2] that can also show fascinating behavior but are much easier to program a computer simulation of and to alter (say, introduce different kinds of vehicles to). Check out the videos on the Wikipedia page to which I've linked, especially [3], to see what I mean. In those videos the blue dots are trying to get from the top to the bottom while the red ones are trying to go from the left edge to the right edge of an "intersection". [1] https://en.wikipedia.org/wiki/Biham%E2%80%93Middleton%E2%80%93Levine_traffic_model https://en.wikipedia.org/wiki/Biham%E2%80%93Middleton%E2%80%... [2] https://www.wolframalpha.com/input/?i=rule+184 https://www.wolframalpha.com/input/?i=rule+184 [3] https://upload.wikimedia.org/wikipedia/commons/1/18/Biham-Middleton-Levine_traffic_model_self-organized_to_a_periodic_intermediate_phase.ogv https://upload.wikimedia.org/wikipedia/commons/1/18/Biham-Mi...

brownbat 13y ago

Jams spontaneously occur after a certain road density is reached. The sadistic side of me wishes they'd just close entrances to the highway whenever it's dangerously full.

makeramen 13y ago

This is really interesting. I wonder if the existing California Highway Patrol practice of swerving around the highway[1] to slow down traffic can be used to create these "anti-traffic" gaps during rush hour? [1] http://articles.latimes.com/1996-08-12/local/me-33464_1_traffic-enforcement http://articles.latimes.com/1996-08-12/local/me-33464_1_traf...

lewispb 13y ago
Near where I live in England we have managed motorways which employ electronic displays and enforce the speed limit with speed cameras. http://en.m.wikipedia.org/wiki/Managed_motorways_in_the_United_Kingdom http://en.m.wikipedia.org/wiki/Managed_motorways_in_the_Unit...

rheide 13y ago

This is the prisoner's dilemma. If you slow down and drive smoothly, and everyone else does too, then everyone benefits greatly. But if you cut in front of one of the smooth drivers, which you can since he's leaving lots of space, you benefit personally by gaining a car length while inconveniencing everyone else in that particular lane. Well, at least until the guy behind you has smoothed out the difference. Human nature makes smoothing out traffic an improbable solution.

Too 13y ago

It's the same as when approaching a red light or any other intersection. If you drive all the way up and make a full stop you will have to accelerate from 0 once you get green. If you slow down when you see the red you can be able to roll into the intersection with speed just as the light switches to green effectively giving you a 30km/h headstart or more. You leave the intersection faster and you save gas by not accelerating. I don't understand why more people don't do this very simple move. The tricky part is timing the switch perfectly which is almost impossible, instead you should just slow down more and more and more and try to never ever fully stop the car fully.

dsego 13y ago
I honestly try this every time and slow down before nearing the intersection. But often there are assholes who overtake and come in front and fill up the road ahead, making me brake and come to a stop as well.
3minus1 13y ago
> just as the light switches to green effectively giving you a 30km/h headstart or more Please be careful with this. If you immediately occupy an intersection after a light turns green there's a chance you'll get blindsided when another car decides to run a red.

sly010 13y ago

Does this mean it's actually possible to improve traffic by introducing extra tempo setter cars whose only job is to smooth traffic?

mooze 13y ago

There's a whole chapter on traffic jams in the book Critical Mass. From what I remember, innocuous things like a single driver slowing down can cause massive jams due to the natural 'physics' of traffic.

frogpelt 13y ago

The merging solution is oversimplified. Leaving enough space for another car in front of you sounds easy. But in reality, if 1,000 cars each add 2 car lengths in front of them you've added 40,000 feet to the length of the slow down. Yep, 7.5 miles. If it was feasible, we could also stop at red lights with 3 or 4 car lengths between each car and when the light turned green everyone could go at the same time. There isn't space on the road for this type of behavior.

jdleesmiller 13y ago

There's a nice simulation of these physics here: http://www.traffic-simulation.de http://www.traffic-simulation.de The jams seem pretty robust, unless you turn down the input flow -- a bit like real life!

jasallen 13y ago

"ON THE RIGHT >>>>> DRIVERS WITH UNUSUAL BEHAVIOR: THEY ENCOURAGE OTHERS TO MERGE AHEAD OF THEM, AND THEY TEND TO MAINTAIN LARGE SPACES AHEAD, EVEN IF TRAFFIC SLOWS TO A CRAWL. MERGING IS EASY. SEE HOW MUCH FASTER THEY GO?" This is misleading 1)The actual throughput of cars through the constriction even in the animation is only slightly faster despite 'apparent' better speeds. 2)The animation does not account for drivers re-assuming their previous following distance. Regardless of whether your 'comfort' distance is half car-length or 5 car lengths, you will eventually resume it. Leading to a slowdown. The advice, and animation seems to assume both that we've merged (onto the highway in the first place) at a rate that can absorb those driving distances without additional slow-down and that we won't resume our previous driving distance (after merging past the constriction). In short, its moved the problem and then shown a window into the part that was improved. *edit: added parenthetics to improve clarity

seanp2k2 13y ago

>"It was dusk, the headlights were on, and I was going down a long hill to the bridges. I had a view of miles of highway behind me. In the other lane I could see maybe five of the traffic stop-waves. But in the lane behind me, for miles, TOTALLY UNIFORM DISTRIBUTION. I hadn't realized it, but by driving at the average speed, my car had been "eating" traffic waves. Everyone ahead of me was caught in the stop/go cycle, while everyone behind me was forced to go at a nice smooth 35MPH or so. My single tiny car had erased miles and miles of stop-and-go traffic. Just one single "lubricant atom" had a profound effect on the turbulent particle flow within the "tube."" When I try this, most other people have no idea what I'm doing and/or are stupidly greedy and go "OMG A GAP" and rush into it. I'll also typically have people behind me honking / flashing their headlights at me, as they're equally clueless. I've had one dude and his wife, in a Harley Davidson edition F150 actually roll down their window and scream at me for "not knowing how to drive". I drive a 6spd stick too, so the stop/go is even more painful. I try to be that "lubricating atom" both for my sanity and to ease the jam, but the collective inability of other drivers to think beyond "OMG MAKE AS MUCH PROGRESS AS SOON AS I CAN" greatly inhibits my efforts. TL;DR traffic jams are caused because people are greedy and short-sighted in their greed. It's not really different from all of the other big problems with humanity.

deleted 13y ago
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jaredmcateer 13y ago
I experienced this as well but you know what, my driving experience is much less stressful on the whole and it's kind of amusing seeing people try to fill that gap by speeding past you only to slam on the brakes as second later.
icambron 13y ago
I have a different theory on why people jump into gaps: they're bored. Traffic jams are really dull, and the illusion of progress is much more entertaining. So not really greed. And it's more ignorance/self-centeredness than short-sightedness; they haven't thought of the jam as a systemic problem to which they're contributing.
13y ago

seanp2k2 13y ago

Even better solution to traffic: develop real high-speed rail in the US, live closer to where you work / need to be (stop suburbs / sprawl), ride bikes or even just motorcycles / mopeds in California where filtering is legal, or walk. This has a lot of other nice first-order benefits like real communities, decreased pollution, less time wasted commuting, and tons of second-order benefits.

pbnjay 13y ago

Someone at Waze should get on this. Send a small notification to Waze users that there's a jam ahead, and to slow down by 10mph to help alleviate it! It's a simple solution and might even work since Waze users are already a "community" of drivers in the sense that they're looking out for each other and not necessarily just themselves.

sigil 13y ago

If you're interested in the physics of it, there's a PDE that explains these backwards propagating density shockwaves (aka traffic jams). http://en.wikipedia.org/wiki/Burgers'_equation http://en.wikipedia.org/wiki/Burgers'_equation

mwexler 13y ago

This appears to be a prettier version of William Beaty's work at http://trafficwaves.org/ http://trafficwaves.org/ which is well worth the read. I send this link out multiple times a year to friends, because it advocates (and shows some proof for) some simple driving changes that can substantially reduce traffic: Leave space ahead of you, and let folks cut in if they want. Given the chaotic pattern of traffic and drivers, these simple habits appear to reduce (but never eliminate) traffic jams.

manojlds 13y ago
Just to be clear, both are by the same person.
- mwexler 13y ago
  Indeed, the article is credited to him, thanks for pointing that out (missed that!). But the original posted site ("smartmotorist") didn't seem to have any credits, so unclear if it's a rip-and-post or if Mr. Beaty was part of "smartmotorist". Regardless, I think Trafficwaves.org gives more info, so wanted to share.
CompelTechnic 13y ago
I love Beaty's stuff. I've tracked his amasci.com for a couple years now- although his updates are few and far between, they are often gems. He's a damn good modern day mad scientist.

WalterBright 13y ago

> My single tiny car had erased miles and miles of stop-and-go traffic. Just one single "lubricant atom" had a profound effect on the turbulent particle flow within the "tube". I did this in the 1970's. It gets rediscovered constantly.