
First rule of ant traffic: no overtaking - chaostheory
http://www.technologyreview.com/blog/arxiv/23176/
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zealog
While it is interesting that there is "no overtaking" in the ant world, I
don't think this really has any real bearing on humans and driving congestion
(as suggested by the articles subheading). Having sat in long, single lane
stop and go traffic I can anecdotally suggest it's irrelevant.

More importantly, there is a big difference between personal locomotion and
commanding a vehicle. For example, the difference between my walking pace and
that of an Olympic champion sprinter is not THAT great. However, the
difference between my freeway merge speed and that of my mom is an order of
magnitude. Add in fixed and inflexible travel lanes, the ability to speed up
and slow down consciously and unconsciously, traveling at speeds that will
knowingly cause death in the event of a problem, etc. and you have a lot more
variance with higher stakes to the participants.

I'm not saying it isn't a fascinating bit of trivia, but I think Tom
Vanderbilt's book "Traffic" is apt to lead to more insight than this
particular nugget of knowledge.

~~~
tlb
The real difference is that stopping distance for an ant is a fraction of an
ant length, but for a car it's several car lengths. So for cars, most of the
space is following distance For ants, most of the space is ants. Car density
decreases as the square of speed, while ant density is constant. That's not
because they have better algorithms but because they're in a different realm
of physics.

------
narag
(Warning: improvised English, this has been very hard for me, sorry)

There is a annoying effect that I can see in my city in most of the jams that
I suffer. It's about the highway exits. The circular highway is usually three
lanes wide. It has exits, many of which are slow (entries to the city). The
exits take the form of an additional lane to the right. When the "contact
zone" of the rightmost lane with the additional lane is long and the traffic
is middle or heavy, the jam is a sure thing.

Why? Even if the exit has a reasonable speed, there are drivers that wait
until the last moment to take the additional lane. There are so many that most
of the vehicles that reach the exit are of this kind. If you are kind enough
to take the additional lane as soon as it is possible, you get caught in a
trap for ten to twenty minutes.

It's a moral dilemma. Either I am a good citizen and agree to be victimized
for a quarter of an hour daily or I do the same to others. Please, don't ask
me what I do.

It also creates a jam for the cars that aren't taking the exit, because the
late changes of lane affect them. Not only the right lane, but also the middle
one are filled with "late-exit-takers". And the slow cars have to change lanes
to avoid the stopped cars waiting to exit.

I've observed that there is a disposition of lanes that prevents the problem:
separating two lanes to exit and two lanes to follow on the highway, making
the exit lanes long enough (to have a "buffer" for the slowness of the exit)
and the fork instant, not a long "contact zone". But this disposition is
seldon used and I haven't really made the experiment to be sure :-)

About the article: I don't think the ants are similar to cars at all. Drivers
have freedom to behave differently, some are in a real hurry and we have
different speed of reaction (to use the holes in the exit to wait to the last
moment).

~~~
eru
Where do you live?

~~~
narag
Madrid, Spain.

------
ams6110
Ants are not trying to text their friends, watch their GPS, and change the
radio station while they are in formation.

------
biotech
This article does make a good point. It has been my experience that highway
traffic can move more quickly when people do not change lanes. I have seen
this happen a couple times in very snowy conditions; the traffic density was
such that it should have been stop & go traffic; however, due to the large
amount of snow between each lane, everyone pretty much stayed in their lane.
This made traffic go at a steady 20-25 mph. (Note that the set of
circumstances in which snow can cause traffic to _speed up_ is very rare).

The main problem that this article does not address is bottlenecks. Even with
a perfect system, it is impossible to keep a constant speed if there is a
large influx of traffic at a certain point or the road narrows to fewer lanes.

------
beholden
The article makes several good points but I'd have to disagree with the no
overtaking rule. Taking the human out of the equation, vis a vis 'IRobot'
style, where road travel is managed by computer seems like a more viable
option in the long term. There have been several advances in this technology,
from MIT especially (Google 'Self driving car', do you really expect me to
divert from this tab for you?)

I work in Highway Engineering and Management, the company i work for manages
quite a few of the UK's motorways. I wonder if I could wing this point into a
meeting. Another Gem HN, thanks.

------
ams6110
The more I think about this the more I think the comparison is not relevant.
Ants are all going from point A (the colony) to point B (the food). Additional
ants are not joining the line midway, nor are any splitting off to some other
destination, nor do different streams of ants cross one another's paths.

If you had a one-way one-lane road with no cross streets, merges, or exits,
MAYBE the situation would be comparable; in the real world, I don't see a
whole lot of relevance.

------
carl_
In "Critical Mass" by Philip Ball chapter 7 covers "The inexorable dynamics of
traffic" which is highly worth a read if this subject matter interests you.
There's also some very interesting sections on crowd dynamics and route
finding.

------
10ren
Ants can form platoons (groups moving at constant speed) because they have the
same destination.

~~~
dsil
We have buses, which do help a good deal.

