

Jerks actually reduce the risk of traffic jams - timf
http://physicsbuzz.physicscentral.com/2009/07/jerks-actually-reduce-risk-of-traffic.html

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kmcgivney
That conclusion is a weakly implied by the research (at least the way it was
explained), which was based on "a computer model of how a crowd of people move
across a confined space".

They did not clarify how it applied to car-traffic. For instance, people react
very differently to minor collisions while walking versus driving. I'm just
guessing here, but I would think the simulation does not account for
complicated behavioral factors (e.g. some people, when cut off, may overrreact
when hitting their brakes, thus causing more traffic behind them).

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ilitirit
The best way to avoid traffic jams is to adjust your speed according to the
person in front of you by accelerating smoothly and decelerating _without
braking_. Sudden stops cause traffic waves.

<http://trafficwaves.org/>

It's best just to leave a big gap between yourself and the car in front of you
and drive at a slower speed. Your average speed will probably end up being the
same anyway as if you had continually accelerated and braked abruptly, but it
would be less frustrating.

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steamer25
The biggest gap in front is left by stopping altogether. This is also the
safest posture a driver can take but it accomplishes nothing.

Yes, leave room in front but also have some consideration for the person
behind you. If I can't (or am not willing to) pass, I try to leave as much
room behind me while staying a safe distance from the vehicle in front of me
as possible.

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yason
In traffic, making space in front of you usually creates safer distances
between those behind you as well.

You slow down a bit so the one who drives behind you gradually drives closer
until he notices that you slowed down. Then he realizes he must slow down as
well, making space between you and him, and the safe distance propagates
further backwards.

~~~
steamer25
Would that this theory worked so well in real life where different drivers
have differing motives for being on the road. If everyone's priority was to
get off of the road as fast as legally possible, you could assume a uniform
speed just below the limit. The only problem left to solve would be creating
space between the vehicles and the approach you've mentioned would likely work
well.

However, the road is full of people who are more concerned about watching the
scenery pass, carrying on a phone conversation or looking for landmarks in
unfamiliar territory. This is perfectly fine until traffic starts backing up
behind them. As cars are added or lanes reduced away, a jam becomes
increasingly imminent. And jams are just the extreme example. Patient
motorists driving slowly behind distracted ones still have their goals
deferred.

What I'm saying is, haste is relative. Slow down if you want to--it's a free
country. Just have some consideration for the people behind you.

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fleaflicker
nyt had a great feature analyzing the effect of the "jersey merge" last year:

<http://www.nytimes.com/2008/08/03/magazine/03traffic-t.html>

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kmcgivney
That's a really good article.

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dhoe
I like it, too. The "early 1900s Dane" not mentioned by name is Erlang, btw.

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HalcyonMuse
Definitely the most amusing journalism piece I've read lately.

It also didn't smack of that whole "I don't know what I'm talking about" thing
that plagues modern journalism.

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baha_man
"However, there is one rule you shouldn't break... the 'three-second rule' for
following distances; after the car ahead of you passes a point on the road,
count to three."

Three seconds? I've heard of the two-second rule, which has an entry on
Wikipedia:

<http://en.wikipedia.org/wiki/Two-second_rule>

When did the extra second get added?

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kirse
I just check how many dashes on the highway... the distance from the beginning
of one "dash" to the beginning of another is 40 feet... So at 70 mph you need
at least 5 dashes.

The two-second rule is definitely the bare minimum... At 70mph that's 210
ft/s, and depending on whether the car in front of you can stop faster, that
might not be enough distance.

~~~
HalcyonMuse
Very cool - I did not know this measurement, though it seems painfully obvious
now that you've pointed it out. I will start using the lane dashes; thanks.

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steamer25
'Platoons' are potential pile-ups++. My wife used seek these out. She said she
thought of them as being like a group 'hug'. It's much safer to spread out a
bit.

The instantaneous risk incurred by speeding away from the group for a bit is
usually far lower than the sum of sustained risk it averts.

Slowing down only helps until there's someone behind you. The real issue is
traffic density. If it's 2AM and you're the only one on the road, you couldn't
cause a wave if you tried. Traffic density can be reduced by increasing the
speed of traffic and or the number of lanes as well as by reducing the number
of vehicles.

Waves are an interesting phenomena to keep in mind but if everyone were to
slow down, there'd be problems at the on-ramps (in addition to the cost in
time just from being slow). You need the guys at the front to speed up until
they can move right/exit to a less-traveled road.

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DanielStraight
At least until they wreck and hold up traffic for hours.

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malvim
Just to clarify for those who didn't RTFA: 40% of jerks is the best. More than
that is counter-productive.

100% of jerks is worse than 100% of non-jerks.

