by mixmastamyk on 5/21/15, 6:44 AM
This reminds me of a piece on traffic I read quite a few years ago and might have been on reddit or even perhaps slashdot. I still follow its advice to this day when having to brave the 101.
It discussed traffic waves and our reactions to them. The repeatable waves this article mentions come from (most of) the individual drivers driving faster than the capacity of the road to carry them all. So they bunch up at some point, catching those in front, everyone slows down for a bit and then the bunch "evaporates" from the front... repeat. Those who get out of the slowdown speed to the next one. It also discussed the effects of merging, which have a high cost as lanes get fuller, also why you'll see lights at on-ramps to mitigate.
The recommendation was to slow down, leave plenty of space ahead for others to merge, and try to get going at as close to a single speed as possible to conserve momentum, gas, wear & tear, nerves, etc. If packed enough you can let the car idle push you along around 5mph/8kph, which is what I aim for in that situation. Feels better than speed-up/break/slow-down over and over.
It also responded to questions such as, "what if everyone around me wants me to go faster?" It happens, but those people tend to drive off in a huff. Once one or two of them do, you'll find a more relaxed driver behind you for the rest of the trip. The impatient driver won't get ahead much anyway so you can wink at them when you catch up at the next slowdown.
by knodi123 on 5/21/15, 2:23 PM
Does anyone else remember the scene in Mission Impossible 3, where tom cruise is hosting a dinner party full of guests who only know his fake cover identity as a statistician working on traffic waves for the department of transportation?
The movie portrays it as conversational kryptonite, where he briefly discusses traffic issues in order to weaponize boredom and get some people to leave him alone.
That part broke my suspension of disbelief, because I was like "Hey, why is everyone wandering away?!? I want to hear what Tom has to say about how to address the problem!"
by dismal2 on 5/21/15, 2:59 PM
If you're in the left lane and going slower than the guy behind you, pull to the right. I wish people in America would be taught this, I'm amazed at how often light traffic I encounter is from a few people meandering in the left most lanes and then everyone behind just matching their speed. Obviously does nothing about major traffic but still annoying. Besides that, people need to stop thinking of driving as a competition and let others change lanes and merge. I'd like to think those 2 things would help the situation a bit.
by sinelaw_ on 5/21/15, 7:08 AM
Nice visualization!
I made something similar a while back (refresh the page if it doesn't start properly):
http://sinelaw.github.io/jammed/src/It includes drivers with different personalities (buses accelerate slower, some drivers are daydreaming, etc.) and lane changing (people change lanes when it's beneficial)
by kokey on 5/21/15, 7:41 AM
I find this happens a lot more in some countries than others, and it's not down to levels of traffic on the road, it's down to driving habits. I think the UK has done well with driver education and variable speed limits to mitigate this, and zipper merging is the norm.
by orik on 5/21/15, 7:41 AM
Whenever the topic of self driving cars comes up in conversation I let people know I think self driving cars are going to solve a lot of our traffic woes.
I'm not sure if a model exists yet for cars 'putting out' traffic waves, but I'm sure once we have self driving cars and they start talking to each other this is going to be of great interest.
I'm hoping we can effectively 'micro' away some degree of congestion.
by tirant on 5/21/15, 8:23 AM
Somehow I always knew this, and I was always driving in a specific manner to combat this effect: I always leave a buffer of space between my car and front car, and whenever I observe oscillations in the car in front, I use my buffer to let my speed oscillate as less as possible.
by jasmcole on 5/21/15, 10:43 AM
Nice. I had a quick look at this effect in an old blog post, it's surprisingly simple to derive the existence of waves in traffic flow (given some simplifying assumptions)
http://jasmcole.com/2014/09/14/only-a-fool/by nradov on 5/21/15, 4:18 PM
Widespread use of adaptive cruise control basically solves this problem. That's the technology where you can set the car to follow a certain distance behind the car in front, and then it accelerates or brakes as necessary. The systems use radar or stereoscopic cameras to measure distance. Once 20%+ of cars on a road segment are using ACC then everything smooths out. Now that the price of ACC has come way down I think the government should offer rebates for purchasing the ACC option on new cars. It would be more cost effective than building new roads or adding lanes.
http://journals.aps.org/pre/abstract/10.1103/PhysRevE.69.066...
by dmvaldman on 5/21/15, 12:23 PM
An interesting point to mention is that the traffic "jam" moves backwards. This is because at the front of the jam, cars are able to accelerate out of it, while at the back o the jam cars are piling up into it. Seen from above the jam is a shock wave moving backwards.
This often upsets people when they get out of a jam only to see there was nothing causing it! In reality what caused it may have been much further up the road.
by blunte on 5/21/15, 8:21 AM
One point that seems often forgotten (or undervalued) is the great different in deceleration vs acceleration. Cars (especially driven by humans) decelerate much more quickly than they accelerate. I didn't get the impression from the simulation that this difference was realistically represented. I think reality is even worse than this simulation illustrates.
by marknow on 5/21/15, 3:14 PM
I wish, for those of us that ride motorcycles in this type of traffic in the US, that all states would adopt a sensible lane-spitting allowance for motorcycles. In country after country, lane-splitting has proven to help reduce congestion, and yet, if I try it here, I'll get a ticket. Ridiculous.
by giltleaf on 5/21/15, 2:38 PM
by larrydag on 5/21/15, 12:57 PM
This is something I love to think about when driving on the highway. I've read so much on it. I've also had some thoughts on recommendations to solve it
1. Divided lanes for 3+ lane highways. Basically a modified HOV lane but no occupancy restriction. The far left lane would have lane dividers with openings every 5 miles (or 3 exits). The middle lane opening every 2-3 miles (or every other exit). The idea is that it would force a certain average speed of traffic and hopefully distance between cars in the respective lanes.
2. Smart roads to adequately distance cars from each other. Either a driver assistance signal or actually controlling the internal cruise control system.
by reuven on 5/21/15, 10:12 AM
A model of this is included in the NetLogo models library, which comes with the NetLogo modeling language:
http://ccl.northwestern.edu/netlogo/models/TrafficBasicIt's fun to see children (and adults!) play with the controls on this model, experimenting with different factors that they think might eventually reduce the congestion.
This model is also a great way to introduce kids to complex systems, in which the large-scale results aren't necessarily as obvious as the individual actions that lead to those results.
by athenot on 5/21/15, 3:11 PM
Atlanta has rolled out variable speed limits on some highways (I285) which attempt to slow down the flow BEFORE people reach the congested area.
I'm not sure how well most users understand how it's supposed to help them go faster by slowing down; a bit more education could be helpful so everyone plays the game.
It is a bit weird seeing the speed limit jump from 45 to 65 then to 35 within the space of a mile…
by shameerc on 5/21/15, 2:51 PM
by Inception on 5/21/15, 3:29 PM
I would never get closer than a car's length away from the driver in front of me if I was driving 60 mph; why should I act any differently when I'm driving 30 mph? Speed is trivial - the gap must be maintained so drivers have the opportunity to react to cars around them without having to make any drastic changes in speed.
by _lce0 on 5/21/15, 1:20 PM
can you see the animations?
my browser refuses to load them because of mixed content .. but html was downloaded over http !?
Blocked loading mixed active content "http://d3js.org/d3.v3.min.js"
ReferenceError: d3 is not defined
by lerouxb on 5/21/15, 11:30 AM
I'm pretty convinced that self driving cars can fix this. Reaction times will be much faster and they can network together to spread out the braking and acceleration. Possibly even merging at high speed.
by egeozcan on 5/21/15, 8:28 AM
by lewis500 on 5/21/15, 4:53 PM
this is one of the first things i ever programmed! cool to see it is seeing the light of day again.