
A Single Autonomous Car Has a Huge Impact on Alleviating Traffic - sprucely
https://www.technologyreview.com/s/607841/a-single-autonomous-car-has-a-huge-impact-on-alleviating-traffic/
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eridius
Watching the video, it looks to me like the key result here is "leaving a big
gap in front of you helps smooth out phantom traffic jams", because that's
basically all the autonomous car did when the traffic jams appeared.

It's also not clear from this video if this actually helps with "real" traffic
jams. The simulated jam here has a very important difference from real ones,
which is everybody's going in a circle, so once a car hits a phantom jam,
they'll keep hitting the same jam repeatedly as it goes around the circle
until the jam is cleared up. But in real traffic, once you hit a phantom jam,
you'll never hit the same jam because it proceeds behind you and doesn't wrap
around.

Which is to say, an autonomous car might be able to smooth out _future_
phantom jams once it hits the first one, if there are a sequence of jam
"waves" instead of just one big one, but in that first one it doesn't have the
buffer in front of it yet. It might still be able to help a little by building
a buffer as it proceeds through the jam in order to reduce the need for cars
behind to keep accelerating and braking, but it won't be able to kill the jam.

And actually, come to think of it, there's another key difference here with a
real traffic jam, which is traffic jams generally occur on high-occupancy
roads, which generally means multi-lane roads. So if an autonomous car builds
a big buffer in the middle of a jam, cars from other lands are just going to
merge in front of it, eliminating the buffer and preventing the autonomous car
from actually doing anything useful.

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TFortunato
Yeah, not sure what the big news is here... "traffic waves" actually have been
talked about for a long time... I remember reading "the science hobbyist"
pages almost 20 years ago (!), about this. I think besides the fact that the
car is autonomous, and maybe more consistent than a human driver would be in
this situation, there is nothing really new here.

[http://trafficwaves.org/](http://trafficwaves.org/)

