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Media post: The end of Phantom Traffic Jams


There are two types of traffic jams. The first is when an actual accident occurs and because the traffic can’t flow smoothly (or at all), vehicles back up behind the accident point. The other is far more common and is referred to as a “Phantom Traffic Jam.” This is when one person slows down, sometimes just to look at something, and the others behind them slow down too. As this ripples down the line, eventually everyone comes to a halt. Phantom traffic jams are frustrating but humans and their physiological response times can’t do much about it. But smart cars can though as we learned from Hiley Mazda of Hurst, a local Mazda dealer in Hurst, TX.

Why Phantom Traffic Jams occur

Phantom traffic jams occur because of the limited reaction time that humans have. As we mentioned, when one car slows down, the car behind it will slow down and the car behind that car slows down and on and on until the traffic just stops. Note that there is nothing actually making the cars stop. It’s just the accumulation of reaction times that builds up until there is no room available to move. Interestingly, if you examine a long chain of cars in a phantom traffic jam, you will see that as it creeps along that a wave-like motion will flow through chain.

Video game simulation

Want to see this wave motion in action? You can with a browser-based video game called Error-Prone. With Error-Prone, you and up to 25 of your friends can control the acceleration of cartoon cars by pressing and releasing a key on a keyboard. Things will end as badly as you might expect, as slight variations in speed cause the chain to stop and then move ahead in “waves.” If you look carefully, you will see that the wave ripples around the circle.


Mathematically, Phantom Traffic Jam waves have been extensively studied. In 2009, a team from the National Science Foundation modeled these waves and even came up with a name for them. They are called “Jamitons.” The team also proposed a technology solution that could eliminate these Jamitons. It was an electronic-assist system that helped drivers to accelerate and decelerate more smoothly so it was less likely that Jamitons would occur. The problem is that this technology required human intervention and training, and this is unlikely to occur in the near future.

Smart cars

Now, we are on the cusp of autonomous self-driving vehicles, we expect that anti-Jamiton technology will be integrated into some vehicles. This will requires a car-to-car communication protocol and likely will be augmented by sensors located on “smart streets.” Advanced algorithms will be created to optimize traffic flow, and cars will give each other the proper space to drive with, anticipating slowdowns and braking.

Smart trucks

As you probably could guess, the trucking industry is quite interested in this technology. Millions of dollars per year are wasted by trucks carrying freight when they get stuck in traffic jams. Combined with autonomous driving systems, the trucking industry is watching the development of anti-Jamiton technology quite closely.

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