10 ms·

Can a single car break a traffic jam?

110 points by chiachun 10y ago

gerbilly 10y ago
I wonder if we'd have as much stop and go traffic if every car on the road was standard. I drive like this just to avoid using the clutch. I'll basically crawl at the average speed in 2nd gear, until traffic speeds up. I suspect truckers may be doing it for the same reason, and their gear ratios mean they would have even more gears to cycle through. Stop and go would be a huge pain for them if they have to come to a full stop.
ianferrel 10y ago
The game Error Prone is cute, but it mostly shows that it's very difficult to keep going a constant speed when your only controls are a binary "Full Throttle" and "Idle".
- Johnny555 10y ago
  Which is exactly how some people drive - an ex- used to make me car sick with the way she drove - rather than maintaing a constant speed, she'd speed up 'till she got too close to the car in front of her (dangerously close), then let off on the gas (or even tap the brakes) to slow down. Annoying and led to no end of arguments "Why are you always criticizing my driving!?".
  - wnissen 10y ago
    With that style of driving, the minimum speed is also far more likely to drop to 0. And when one person is stopped, everyone behind them is stopped. Even for people who don't normally drive that way, add in a cell phone and that's exactly what starts to happen because they don't have enough remaining attention to avoid being "surprised" by a stopped car.
revscat 10y ago
This is almost a perfect metaphor for the failings of capitalism, or at they very least the notion that the singular pursuit of selfish greed can lead to ideal outcomes. The selfish need for individual drivers to go as fast as they can leads to a collective failure, here in the form of a traffic jam.
- bpodgursky 10y ago
  Or, if you insist on bringing politics into unrelated topics, it's a failing of a commodity that hasn't been properly marketized. You have to externalize the cost of bad behavior by making it a proper market.
  - galdosdi 10y ago
    It is fun to imagine how you could set up a price structure that incentivizes the right things to prevent traffic jams. For example: * A small per-second fee that is inversely related to the distance between your vehicle and the vehicle in front or behind you, whichever is closer. Maybe the distance scale would be dynamic based on speed, maybe measured in "estimated stopping time", such as (just as one wild example) a certain fee for being at 100% of safe estimated minimum stopping distance, a smaller one for 200%, a higher one for 50%, negligible or no fee for more than 1000%, * A penalty fee for changing lanes. In dense or stop and go traffic, changing lanes imposes a pretty large cost on nearby traffic, as both lanes are stopped for a bit. Grass-is-greener temptation causes many drivers to change lanes, which quickly eliminates any sought advantage, but makes traffic worse as drivers essentially take up double space. * etc? Then dynamically tune the fees to get the desired result. Watch as frugal drivers economize by * avoiding tailgating and unnecessary lane changing * (because of the "minimum of distances" rule) learn to, in denser traffic, balance their available space between front and rear neighbors. * are loathe to go too slow without making it easier for faster traffic to pass (if you want to enforce speed limits, maybe the distance-to-rear-neighbor cost should only be enforced when travelling below the speed limit?) * Per-second instead of per-mile fees encourage drivers to avoid already jammed areas As for hardware -- I guess the kind of hardware needed for adaptive cruise control / lane maintenance/merge assist now found on fancier vehicles is sufficient to measure and operate this (as long as few people successfully hack their toll measurement system, which I honestly think is realistic).
jetengine 10y ago
This game is easy to beat. Wreck most cars except a few, get a single car in the inner circle by slightly bumping it and press and hold the corresponding key. 62.8 kilometers covered.
sickbeard 10y ago
Vehicles talking to each other will not break a practical traffic jam. The one caused because one car had to stop for some reason or other, now everyone has to stop or slow down in the same vicinity until there are less cars flowing through the area.
- creeble 10y ago
  I'm not so sure. I think the big difference it would make to have cars talking to each other is that they can all know where the other (within a local range) is heading, make interchanges more optimal. A lot of traffic congestion happens because we have nothing but (too-infrequently-used) turn signals to indicate our intentions. If all the cars knew where they were going at an interchange, you could at least optimize the flow. Of course, there is _no_ solution when there are just too many cars trying to fit on a road that can't handle it. And that's probably 80-90% of the problem anyway :(
xbryanx 10y ago
William J Beaty's video on Traffic Waves (linked in the article) is an enjoyable summary of some of these ideas: https://www.youtube.com/watch?v=iGFqfTCL2fs https://www.youtube.com/watch?v=iGFqfTCL2fs
noonshine 10y ago
I have adaptive cruise control in my Subaru Legacy and I have often wondered what will happen when more people have ACC. Or even if I were following another car exactly like mine - would the lag time grow exponentially with more intense stop/go or would it even out? Or does it depend on how well the car implements it?
- blakeyrat 10y ago
  The adaptive cruise control in my Ford turns itself off if the speed is low enough-- which on Seattle-area freeways happens pretty often. So I stopped trying to use it.
  - ahlatimer 10y ago
    The Subaru one stays on until you come to a complete stop. Even then, it's still "on" in a way, since it'll hold the brakes, but you have to flick up on the cruise control switch to get the car to start moving again. It'll also notify you if the car in front has started moving again and you haven't done anything (with or without ACC on). It's on my girlfriend's car, so I don't use it every day, but it has been nice the times I've driven it in traffic.
- daveguy 10y ago
  I used ACC on my mom's hybrid Accord recently and it was an aweful experience. It was like regular cruise control, but broken. Lagging start, unnecessary distances, slow responses. That and the out of lane beep whenever I passed a car (staying in the same lane but getting to the edge of the lane for increased margin of error) was really annoying. If this is the future of assisted driving, just give me fully automated driving.
- arprocter 10y ago
  There was an Acura ad recently which said the car would change your route if it knew there was a jam ahead. I thought 'what happens if the ad is so successful everyone buys that Acura?'
  - 10y ago
cortesoft 10y ago
This sort of traffic jam dissipation is only applicable to phantom traffic jams. Here in Los Angeles, traffic jams are caused by too many cars being on the road. At some point, every available square foot of roadway is filled with a car. AI can help limit the amount of extra space taken up by air, but that will only moderately increase the number of cars that it will take before traffic hits. That number of cars will be reached, easily.
- cft 10y ago
  AI will eliminate truck night stops, allowing them to be driven 24/7. Hopefully more trucks will be moving at night. That should reduce the jams.
  - cortesoft 10y ago
    Not sure how much you have driven in Los Angeles....we also have traffic jams at night.
  - SwellJoe 10y ago
    Not only that, AI will eliminate huge amounts of wasted road even during peak times and with traffic that can't be scheduled for off hours (like people going to work/school). A networked self-driving car can know where the traffic is and route around it. It can provide tools to everyone (from city planners to individuals) to maximize the availability of resources and minimize the time wasted on waiting. Red lights can cycle at the most efficient rate at all hours of the day, reversible lanes (like many large cities have on their primary highways) can be closed and opened on a dynamic schedule rather than on the preset schedule. When all cars are AI-driven and aware of all other cars, they can drive at exactly the right speed, allowing faster merges and exits, etc. Humans are wildly variable in their response time and unpredictable in their behavior in so many situations on the road, that replacing them seems likely to increase the capacity of roads by a dramatic amount. Maybe doubling? Maybe tripling? I don't know, but it will be a huge difference.
    - j_s 10y ago
      Yes, all (but one?) lane going in the "to/from work" direction based on traffic needs will make a huge difference!
logn 10y ago
I often try the technique of leaving lots of space and going at a slower, steady pace. One problem is that everyone re-routes around you, and you induce road rage and traffic weaving. The other problem is that unless it's a straight stretch of road, you have no idea what speed is slow enough.
- GigabyteCoin 10y ago
  Truckers (professional drivers) do this all the time. If ever there is a traffic jam on the highway, you will see the big rigs consistently leaving hundreds of feet of space in front of them. They also seem to concentrate in the center lanes of the highway for reasons I haven't figured out yet.
  - mhurron 10y ago
    > They also seem to concentrate in the center lanes of the highway for reasons I haven't figured out yet. Most likely because if a lane is closed it will be an edge lane. Also, if you're on a 3 lane road and two lanes are closed, you only have to make one lane change to keep going.
  - seizethecheese 10y ago
    Semi-trucks are generally not allowed in the left lane on the freeway, and the right must be a nightmare of merging for semi-trucks in traffic.
    - colejohnson66 10y ago
      Not to mention that if the right lane is an "exit only" lane, merging a truck over a lane is pretty hard. No one wants to leave enough room. Or when you do leave enough room, some idiot sees that giant opening and moves into it.
  - cpeterso 10y ago
    In a traffic jam, wouldn't the alternative to leaving plenty of space be constantly starting and stopping? That seems pretty like a lot of work for the driver in a big rig.
Coincoin 10y ago
Over here, I noticed it is much more pleasant to be stuck in rush hour traffic than off peak. At peak hour, people know the game and know they won't get anywhere faster by cutting and trying to fight for every inch. They tend to stay in their lane, merge smoothly and all lanes go the same speed. But as soon as the traffic lightens a bit, idiots just come back to break the peace. I include myself in those.
stevebmark 10y ago
Traffic jams exist because humans drive cars, and humans are not designed to process data at 120 kilometers per hour. This is a major repost but still misses the main problem. When you look at a car in front of you, you perceive it as a stationary wall, not a moving wall. When you slow down, you're trying to avoid hitting where the car in front of you is when you press on the brake pedal. You're not smart enough to realize that you should be slowing down to avoid hitting where the car will be when that car stops. You do this, and you should not be driving cars. Leaving space in front of you is an inefficient solution to this problem, now you're overcompensating even more for the problem. You can try watching one car ahead of the one in front of you to predict when the car in front of you will slow down and need to stop. Your passengers will freak out, constantly thinking you're going to hit the car directly in front of you, because they perceive the car in front of you as a stationary wall. In reality, you're driving more efficiently. The day when us unevolved meat sacks stop controlling two ton metal bullets can't come soon enough.
- to3m 10y ago
  But my car weighs only 1600kg, and for years my passengers have been telling me I'm going to hit the car directly in front of me. Looks like that day has already come ;)
DonaldFisk 10y ago
Traffic jams are often causes in the way the article suggests, and if you drive at the average speed, instead of the maximum legal or safe speed whenever you can, there's a good change the jam will have dissipated just before you reach it, and you'll get where you want to go just as fast. This means that the cars behind you (provided it stays behind you) also don't have to stop. Their drivers should thank you for saving their fuel rather than curse you for driving too slow. To minimize fuel consumption, it's best to drive in the highest gear, at the lowest speed for that gear. Failing that, to drive at a constant speed in the highest gear for that speed. If you do have to slow down, ease off the accelerator and change down gears, rather than use the brake. This means thinking ahead. You can do this when approaching a red traffic light, so that it will be green by the time you reach it. There are a few other tricks to save fuel, such as driving at the minimum safe distance behind a big rig, and using gravity on hills to slow down or speed up. This is sometimes called hypermiling: https://en.wikipedia.org/wiki/Energy-efficient_driving https://en.wikipedia.org/wiki/Energy-efficient_driving
StillBored 10y ago
This theory has been running around for a a few decades now. But a couple years ago I read a paper where they were studying traffic jams, and the conclusion is that elastic traffic is the problem, and this technique does nothing really to solve the problem. Instead simply maintaining the exact same spacing in front/back of your vehicle does a much better job of avoiding and clearing traffic jams.
elchief 10y ago
The trick is to leave enough room in front of you so you don't have to jam the brakes, but not enough room that some fucker will pull in front of you. I also try to jump into the left lane at an intersection stop, if there's no left turner, to let people turn right
- serge2k 10y ago
  > not enough room that some fucker will pull in front of you. why does it matter, most of the time?
  - arprocter 10y ago
    Because then you have to slow down to open a new gap. And then once you do some other genius pulls into the space. Repeat for entirety of journey.
talldan 10y ago
When driving I've also noticed another phenomenon. When reaching the crest of a hill there's an optical illusion that cars are bunched together. From this viewpoint the driver can see more of the road and vehicles ahead. My theory is that this causes a momentary shock or panic, and it often causes drivers to slam on the brakes, causing ripples of braking behind them.
arprocter 10y ago
I wonder how much of this is mitigated by good lane discipline? My SO actually got pulled over the other day (or at least that's what the cop used as an excuse) for driving in a passing lane when not passing anything. I said I was glad because it's a terrible habit - every lane ending up going the same speed as the slowest driver
- gerbilly 10y ago
  >every lane ending up going the same speed as the slowest driver And if two drivers drive abreast, then it's like having two roads going to the same place, where no one can pass anyone.
- danenania 10y ago
  Lane discipline makes a huge difference. It's what makes driving 110mph on the Autobahn safer than driving 70 on a busy US highway.
cortesoft 10y ago
Every time people try to say we can eliminate traffic if we just leave space in between cars, I think of this great article: http://jliszka.github.io/2013/10/01/how-traffic-actually-works.html http://jliszka.github.io/2013/10/01/how-traffic-actually-wor... TL;DR there is an effective maximum number of cars that can pass through a given point of roadway (about 1 car per 2 seconds per lane). No amount of space-leaving is going to chance that.
- tetraodonpuffer 10y ago
  I think you need to read the update #2 in the page you linked, of course you can't create capacity out of nowhere, but if you are in a "phantom jam" situation it does help to "smooth things out" as the page clarifies (which I think is what this article is about)
  - cortesoft 10y ago
    I guess I am just not used to that sort of traffic jam where I am. Here, it is always just 'way too many fucking cars on the road'
    - janekm 10y ago
      In that traffic jam, is 1 car passing that point every 2s? No? Then I guess your road is not operating at peak capacity.
      - cortesoft 10y ago
        That is the maximum number of cars that can pass a given point in 2 seconds; it does not mean that a road operating at peak capacity can reach that number. You also have to take into account cars merging onto the road you are on. Imagine a road acting at peak efficiency, with a car passing every 2 seconds. Now merge in more cars. They are going to push back every car behind by that same 2 seconds. You can read the section on 'merging' in the link above to read more details.
mjevans 10y ago
No, at least not for I-405 / I-5 near Seattle. These roads, due to a complete lack of effective urban planning and development, are several times over capacity. I like to think that this heuristic would be effective for such cases. * Aim for a hard speed limit (maybe the actual speed limit). * Actually obey the law of this state: Keep Right Except to Pass. * ALWAYS allow merges (from either side) with higher priority. Edit: After reading the github link from one of the other posts I want to expand why I disagree and suggest always allowing merges. It is to allow traffic to leave the freeway (merge right to exit) as well as to enter the freeway (merge left, mostly to enter at all, but also in case they're going a long distance or need to get to special use lanes on the left).
- PantaloonFlames 10y ago
  > Aim for a hard speed limit (maybe the actual speed limit). That's not gonna work. Depends on the day, the time, the weather, rain, fog etc. Some days, traffic flows at 70 on 405 during rush hour. If you go the legal speed limit you will be the dangerous blockage that makes everyone else down, and makes a few people unnecessarily grumpy. Other days it's misty because the water on the road gets stirred up by all the trucks. It's impossible to go the speed limit on these days, the flow is going 45. There is no hard rule, except: go with the flow. SEE the traffic. BE the traffic. Do not FIGHT the traffic.
  - ThrustVectoring 10y ago
    Enforcing a speed limit on freeways is completely possible. They've got it done in England. What you need to do is capture license plates on entrance and exit, and calculate the average speed for each car's trip. If the speed limit is 50 MPH for traffic-flow reasons, and you do your 15 mile commute in 15 minutes, you're getting a "60 in a 50 MPH zone" ticket in the mail, every single time. People will learn in a hurry that speeding is pretty much pointless and self-harming.
    - noarchy 10y ago
      They've really got the surveillance state thing down to a science there, if they're doing things like that. In North America, where there are cameras, they tend to only look at your speed at a specific moment.
mjevans 10y ago
I want to propose a second more radical suggestion. I think pacer cars might work very well for phantom traffic jams, but I very much disagree about /how/ they should be used. Instead of encouraging an over-capacity jam, I believe that the pacer cars should expressly communicate to other traffic something along the lines of. "Temporary" / "Speed Limit" / "Follow at XX" On a rear message board. The pacer car would then draw out the stuck traffic in to the space /ahead/ of the jam and encourage the compression wave to expand to the front instead.
mannykannot 10y ago
While, in the right environment, a single driver may be able to break a jam, a single driver can create one just about anywhere.
afterburner 10y ago
I would avoid blaming any traffic on "non-optimal" driving by other drivers (not leaving enough space so they maintain constant speed, stuff like that), since it's just another recipe for road rage.
mathogre 10y ago
I just had fun crashing cars. 25 crashed with 1.8km travelled. I know it's not the point, but I don't care (nod to Icona Pop). I love it. I needed the laugh.
piracyde25 10y ago
Somewhat related to this traffic hobbyist, written on 1998-- http://trafficwaves.org/ http://trafficwaves.org/
- Lorin 10y ago
  Somewhat related? It's linked in the second part of the article :/
feelix 10y ago
I've always wanted to see what would happen if the government employed workers (maybe traffic cops) to take up each lane on the motorway, and form a line that you can't get passed, and drive at a speed just right to unclog traffic jams during peak hours. I wonder how much more throughput and time saved we could get just by having lines of breakers every 50km or so on a highway during peak times.
Houshalter 10y ago
A long long time ago, I stumbled onto the personal website of a guy who was really into this. He had little simulations of different types of traffic patterns, and how a single car could break it and return it to normal. It was really interesting, but I don't have the slightest idea on how to find that website again if it even still exists. EDIT: Found in the comments, this may have been it. Honestly don't remember: http://trafficwaves.org/ http://trafficwaves.org/
- furyofantares 10y ago
  This was one of the first sites I remember finding, in the late 90s. Back then it was hosted on the personal website provided by the author's dialup ISP, eskimo.com, as I recall. Edit: I just noticed it still is hosted by eskimo.com, it just has its own domain now.
mdotk 10y ago
Without AI, the answer today is to drive as fast as possible all the time.

110 points by chiachun 10y ago

I wonder if we'd have as much stop and go traffic if every car on the road was standard. I drive like this just to avoid using the clutch. I'll basically crawl at the average speed in 2nd gear, until traffic speeds up. I suspect truckers may be doing it for the same reason, and their gear ratios mean they would have even more gears to cycle through. Stop and go would be a huge pain for them if they have to come to a full stop.

ianferrel 10y ago

The game Error Prone is cute, but it mostly shows that it's very difficult to keep going a constant speed when your only controls are a binary "Full Throttle" and "Idle".

Johnny555 10y ago
Which is exactly how some people drive - an ex- used to make me car sick with the way she drove - rather than maintaing a constant speed, she'd speed up 'till she got too close to the car in front of her (dangerously close), then let off on the gas (or even tap the brakes) to slow down. Annoying and led to no end of arguments "Why are you always criticizing my driving!?".
- wnissen 10y ago
  With that style of driving, the minimum speed is also far more likely to drop to 0. And when one person is stopped, everyone behind them is stopped. Even for people who don't normally drive that way, add in a cell phone and that's exactly what starts to happen because they don't have enough remaining attention to avoid being "surprised" by a stopped car.

revscat 10y ago

This is almost a perfect metaphor for the failings of capitalism, or at they very least the notion that the singular pursuit of selfish greed can lead to ideal outcomes. The selfish need for individual drivers to go as fast as they can leads to a collective failure, here in the form of a traffic jam.

bpodgursky 10y ago
Or, if you insist on bringing politics into unrelated topics, it's a failing of a commodity that hasn't been properly marketized. You have to externalize the cost of bad behavior by making it a proper market.
- galdosdi 10y ago
  It is fun to imagine how you could set up a price structure that incentivizes the right things to prevent traffic jams. For example: * A small per-second fee that is inversely related to the distance between your vehicle and the vehicle in front or behind you, whichever is closer. Maybe the distance scale would be dynamic based on speed, maybe measured in "estimated stopping time", such as (just as one wild example) a certain fee for being at 100% of safe estimated minimum stopping distance, a smaller one for 200%, a higher one for 50%, negligible or no fee for more than 1000%, * A penalty fee for changing lanes. In dense or stop and go traffic, changing lanes imposes a pretty large cost on nearby traffic, as both lanes are stopped for a bit. Grass-is-greener temptation causes many drivers to change lanes, which quickly eliminates any sought advantage, but makes traffic worse as drivers essentially take up double space. * etc? Then dynamically tune the fees to get the desired result. Watch as frugal drivers economize by * avoiding tailgating and unnecessary lane changing * (because of the "minimum of distances" rule) learn to, in denser traffic, balance their available space between front and rear neighbors. * are loathe to go too slow without making it easier for faster traffic to pass (if you want to enforce speed limits, maybe the distance-to-rear-neighbor cost should only be enforced when travelling below the speed limit?) * Per-second instead of per-mile fees encourage drivers to avoid already jammed areas As for hardware -- I guess the kind of hardware needed for adaptive cruise control / lane maintenance/merge assist now found on fancier vehicles is sufficient to measure and operate this (as long as few people successfully hack their toll measurement system, which I honestly think is realistic).

jetengine 10y ago

This game is easy to beat. Wreck most cars except a few, get a single car in the inner circle by slightly bumping it and press and hold the corresponding key. 62.8 kilometers covered.

sickbeard 10y ago

Vehicles talking to each other will not break a practical traffic jam. The one caused because one car had to stop for some reason or other, now everyone has to stop or slow down in the same vicinity until there are less cars flowing through the area.

creeble 10y ago
I'm not so sure. I think the big difference it would make to have cars talking to each other is that they can all know where the other (within a local range) is heading, make interchanges more optimal. A lot of traffic congestion happens because we have nothing but (too-infrequently-used) turn signals to indicate our intentions. If all the cars knew where they were going at an interchange, you could at least optimize the flow. Of course, there is _no_ solution when there are just too many cars trying to fit on a road that can't handle it. And that's probably 80-90% of the problem anyway :(

xbryanx 10y ago

William J Beaty's video on Traffic Waves (linked in the article) is an enjoyable summary of some of these ideas: https://www.youtube.com/watch?v=iGFqfTCL2fs https://www.youtube.com/watch?v=iGFqfTCL2fs

noonshine 10y ago

I have adaptive cruise control in my Subaru Legacy and I have often wondered what will happen when more people have ACC. Or even if I were following another car exactly like mine - would the lag time grow exponentially with more intense stop/go or would it even out? Or does it depend on how well the car implements it?

blakeyrat 10y ago
The adaptive cruise control in my Ford turns itself off if the speed is low enough-- which on Seattle-area freeways happens pretty often. So I stopped trying to use it.
- ahlatimer 10y ago
  The Subaru one stays on until you come to a complete stop. Even then, it's still "on" in a way, since it'll hold the brakes, but you have to flick up on the cruise control switch to get the car to start moving again. It'll also notify you if the car in front has started moving again and you haven't done anything (with or without ACC on). It's on my girlfriend's car, so I don't use it every day, but it has been nice the times I've driven it in traffic.
daveguy 10y ago
I used ACC on my mom's hybrid Accord recently and it was an aweful experience. It was like regular cruise control, but broken. Lagging start, unnecessary distances, slow responses. That and the out of lane beep whenever I passed a car (staying in the same lane but getting to the edge of the lane for increased margin of error) was really annoying. If this is the future of assisted driving, just give me fully automated driving.
arprocter 10y ago
There was an Acura ad recently which said the car would change your route if it knew there was a jam ahead. I thought 'what happens if the ad is so successful everyone buys that Acura?'
- 10y ago

cortesoft 10y ago

This sort of traffic jam dissipation is only applicable to phantom traffic jams. Here in Los Angeles, traffic jams are caused by too many cars being on the road. At some point, every available square foot of roadway is filled with a car. AI can help limit the amount of extra space taken up by air, but that will only moderately increase the number of cars that it will take before traffic hits. That number of cars will be reached, easily.

cft 10y ago
AI will eliminate truck night stops, allowing them to be driven 24/7. Hopefully more trucks will be moving at night. That should reduce the jams.
- cortesoft 10y ago
  Not sure how much you have driven in Los Angeles....we also have traffic jams at night.
- SwellJoe 10y ago
  Not only that, AI will eliminate huge amounts of wasted road even during peak times and with traffic that can't be scheduled for off hours (like people going to work/school). A networked self-driving car can know where the traffic is and route around it. It can provide tools to everyone (from city planners to individuals) to maximize the availability of resources and minimize the time wasted on waiting. Red lights can cycle at the most efficient rate at all hours of the day, reversible lanes (like many large cities have on their primary highways) can be closed and opened on a dynamic schedule rather than on the preset schedule. When all cars are AI-driven and aware of all other cars, they can drive at exactly the right speed, allowing faster merges and exits, etc. Humans are wildly variable in their response time and unpredictable in their behavior in so many situations on the road, that replacing them seems likely to increase the capacity of roads by a dramatic amount. Maybe doubling? Maybe tripling? I don't know, but it will be a huge difference.
  - j_s 10y ago
    Yes, all (but one?) lane going in the "to/from work" direction based on traffic needs will make a huge difference!

logn 10y ago

I often try the technique of leaving lots of space and going at a slower, steady pace. One problem is that everyone re-routes around you, and you induce road rage and traffic weaving. The other problem is that unless it's a straight stretch of road, you have no idea what speed is slow enough.

GigabyteCoin 10y ago
Truckers (professional drivers) do this all the time. If ever there is a traffic jam on the highway, you will see the big rigs consistently leaving hundreds of feet of space in front of them. They also seem to concentrate in the center lanes of the highway for reasons I haven't figured out yet.
- mhurron 10y ago
  > They also seem to concentrate in the center lanes of the highway for reasons I haven't figured out yet. Most likely because if a lane is closed it will be an edge lane. Also, if you're on a 3 lane road and two lanes are closed, you only have to make one lane change to keep going.
- seizethecheese 10y ago
  Semi-trucks are generally not allowed in the left lane on the freeway, and the right must be a nightmare of merging for semi-trucks in traffic.
  - colejohnson66 10y ago
    Not to mention that if the right lane is an "exit only" lane, merging a truck over a lane is pretty hard. No one wants to leave enough room. Or when you do leave enough room, some idiot sees that giant opening and moves into it.
- cpeterso 10y ago
  In a traffic jam, wouldn't the alternative to leaving plenty of space be constantly starting and stopping? That seems pretty like a lot of work for the driver in a big rig.

Coincoin 10y ago

Over here, I noticed it is much more pleasant to be stuck in rush hour traffic than off peak. At peak hour, people know the game and know they won't get anywhere faster by cutting and trying to fight for every inch. They tend to stay in their lane, merge smoothly and all lanes go the same speed. But as soon as the traffic lightens a bit, idiots just come back to break the peace. I include myself in those.

stevebmark 10y ago

Traffic jams exist because humans drive cars, and humans are not designed to process data at 120 kilometers per hour. This is a major repost but still misses the main problem. When you look at a car in front of you, you perceive it as a stationary wall, not a moving wall. When you slow down, you're trying to avoid hitting where the car in front of you is when you press on the brake pedal. You're not smart enough to realize that you should be slowing down to avoid hitting where the car will be when that car stops. You do this, and you should not be driving cars. Leaving space in front of you is an inefficient solution to this problem, now you're overcompensating even more for the problem. You can try watching one car ahead of the one in front of you to predict when the car in front of you will slow down and need to stop. Your passengers will freak out, constantly thinking you're going to hit the car directly in front of you, because they perceive the car in front of you as a stationary wall. In reality, you're driving more efficiently. The day when us unevolved meat sacks stop controlling two ton metal bullets can't come soon enough.

to3m 10y ago
But my car weighs only 1600kg, and for years my passengers have been telling me I'm going to hit the car directly in front of me. Looks like that day has already come ;)

DonaldFisk 10y ago

Traffic jams are often causes in the way the article suggests, and if you drive at the average speed, instead of the maximum legal or safe speed whenever you can, there's a good change the jam will have dissipated just before you reach it, and you'll get where you want to go just as fast. This means that the cars behind you (provided it stays behind you) also don't have to stop. Their drivers should thank you for saving their fuel rather than curse you for driving too slow. To minimize fuel consumption, it's best to drive in the highest gear, at the lowest speed for that gear. Failing that, to drive at a constant speed in the highest gear for that speed. If you do have to slow down, ease off the accelerator and change down gears, rather than use the brake. This means thinking ahead. You can do this when approaching a red traffic light, so that it will be green by the time you reach it. There are a few other tricks to save fuel, such as driving at the minimum safe distance behind a big rig, and using gravity on hills to slow down or speed up. This is sometimes called hypermiling: https://en.wikipedia.org/wiki/Energy-efficient_driving https://en.wikipedia.org/wiki/Energy-efficient_driving

StillBored 10y ago

This theory has been running around for a a few decades now. But a couple years ago I read a paper where they were studying traffic jams, and the conclusion is that elastic traffic is the problem, and this technique does nothing really to solve the problem. Instead simply maintaining the exact same spacing in front/back of your vehicle does a much better job of avoiding and clearing traffic jams.

elchief 10y ago

The trick is to leave enough room in front of you so you don't have to jam the brakes, but not enough room that some fucker will pull in front of you. I also try to jump into the left lane at an intersection stop, if there's no left turner, to let people turn right

serge2k 10y ago
> not enough room that some fucker will pull in front of you. why does it matter, most of the time?
- arprocter 10y ago
  Because then you have to slow down to open a new gap. And then once you do some other genius pulls into the space. Repeat for entirety of journey.

talldan 10y ago

When driving I've also noticed another phenomenon. When reaching the crest of a hill there's an optical illusion that cars are bunched together. From this viewpoint the driver can see more of the road and vehicles ahead. My theory is that this causes a momentary shock or panic, and it often causes drivers to slam on the brakes, causing ripples of braking behind them.

arprocter 10y ago

I wonder how much of this is mitigated by good lane discipline? My SO actually got pulled over the other day (or at least that's what the cop used as an excuse) for driving in a passing lane when not passing anything. I said I was glad because it's a terrible habit - every lane ending up going the same speed as the slowest driver

gerbilly 10y ago
>every lane ending up going the same speed as the slowest driver And if two drivers drive abreast, then it's like having two roads going to the same place, where no one can pass anyone.
danenania 10y ago
Lane discipline makes a huge difference. It's what makes driving 110mph on the Autobahn safer than driving 70 on a busy US highway.

cortesoft 10y ago

Every time people try to say we can eliminate traffic if we just leave space in between cars, I think of this great article: http://jliszka.github.io/2013/10/01/how-traffic-actually-works.html http://jliszka.github.io/2013/10/01/how-traffic-actually-wor... TL;DR there is an effective maximum number of cars that can pass through a given point of roadway (about 1 car per 2 seconds per lane). No amount of space-leaving is going to chance that.

tetraodonpuffer 10y ago
I think you need to read the update #2 in the page you linked, of course you can't create capacity out of nowhere, but if you are in a "phantom jam" situation it does help to "smooth things out" as the page clarifies (which I think is what this article is about)
- cortesoft 10y ago
  I guess I am just not used to that sort of traffic jam where I am. Here, it is always just 'way too many fucking cars on the road'
  - janekm 10y ago
    In that traffic jam, is 1 car passing that point every 2s? No? Then I guess your road is not operating at peak capacity.
    - cortesoft 10y ago
      That is the maximum number of cars that can pass a given point in 2 seconds; it does not mean that a road operating at peak capacity can reach that number. You also have to take into account cars merging onto the road you are on. Imagine a road acting at peak efficiency, with a car passing every 2 seconds. Now merge in more cars. They are going to push back every car behind by that same 2 seconds. You can read the section on 'merging' in the link above to read more details.

mjevans 10y ago

No, at least not for I-405 / I-5 near Seattle. These roads, due to a complete lack of effective urban planning and development, are several times over capacity. I like to think that this heuristic would be effective for such cases. * Aim for a hard speed limit (maybe the actual speed limit). * Actually obey the law of this state: Keep Right Except to Pass. * ALWAYS allow merges (from either side) with higher priority. Edit: After reading the github link from one of the other posts I want to expand why I disagree and suggest always allowing merges. It is to allow traffic to leave the freeway (merge right to exit) as well as to enter the freeway (merge left, mostly to enter at all, but also in case they're going a long distance or need to get to special use lanes on the left).

PantaloonFlames 10y ago
> Aim for a hard speed limit (maybe the actual speed limit). That's not gonna work. Depends on the day, the time, the weather, rain, fog etc. Some days, traffic flows at 70 on 405 during rush hour. If you go the legal speed limit you will be the dangerous blockage that makes everyone else down, and makes a few people unnecessarily grumpy. Other days it's misty because the water on the road gets stirred up by all the trucks. It's impossible to go the speed limit on these days, the flow is going 45. There is no hard rule, except: go with the flow. SEE the traffic. BE the traffic. Do not FIGHT the traffic.
- ThrustVectoring 10y ago
  Enforcing a speed limit on freeways is completely possible. They've got it done in England. What you need to do is capture license plates on entrance and exit, and calculate the average speed for each car's trip. If the speed limit is 50 MPH for traffic-flow reasons, and you do your 15 mile commute in 15 minutes, you're getting a "60 in a 50 MPH zone" ticket in the mail, every single time. People will learn in a hurry that speeding is pretty much pointless and self-harming.
  - noarchy 10y ago
    They've really got the surveillance state thing down to a science there, if they're doing things like that. In North America, where there are cameras, they tend to only look at your speed at a specific moment.

mjevans 10y ago

I want to propose a second more radical suggestion. I think pacer cars might work very well for phantom traffic jams, but I very much disagree about /how/ they should be used. Instead of encouraging an over-capacity jam, I believe that the pacer cars should expressly communicate to other traffic something along the lines of. "Temporary" / "Speed Limit" / "Follow at XX" On a rear message board. The pacer car would then draw out the stuck traffic in to the space /ahead/ of the jam and encourage the compression wave to expand to the front instead.

mannykannot 10y ago

While, in the right environment, a single driver may be able to break a jam, a single driver can create one just about anywhere.

afterburner 10y ago

I would avoid blaming any traffic on "non-optimal" driving by other drivers (not leaving enough space so they maintain constant speed, stuff like that), since it's just another recipe for road rage.

mathogre 10y ago

I just had fun crashing cars. 25 crashed with 1.8km travelled. I know it's not the point, but I don't care (nod to Icona Pop). I love it. I needed the laugh.

piracyde25 10y ago

Somewhat related to this traffic hobbyist, written on 1998-- http://trafficwaves.org/ http://trafficwaves.org/

Lorin 10y ago
Somewhat related? It's linked in the second part of the article :/

feelix 10y ago

I've always wanted to see what would happen if the government employed workers (maybe traffic cops) to take up each lane on the motorway, and form a line that you can't get passed, and drive at a speed just right to unclog traffic jams during peak hours. I wonder how much more throughput and time saved we could get just by having lines of breakers every 50km or so on a highway during peak times.

Houshalter 10y ago

A long long time ago, I stumbled onto the personal website of a guy who was really into this. He had little simulations of different types of traffic patterns, and how a single car could break it and return it to normal. It was really interesting, but I don't have the slightest idea on how to find that website again if it even still exists. EDIT: Found in the comments, this may have been it. Honestly don't remember: http://trafficwaves.org/ http://trafficwaves.org/

furyofantares 10y ago
This was one of the first sites I remember finding, in the late 90s. Back then it was hosted on the personal website provided by the author's dialup ISP, eskimo.com, as I recall. Edit: I just noticed it still is hosted by eskimo.com, it just has its own domain now.

mdotk 10y ago

Without AI, the answer today is to drive as fast as possible all the time.