

Traffic jams are not caused by flaws in road design but by flaws in human nature. - robg
http://www.nytimes.com/2008/08/10/books/review/Roach-t.html?partner=rssuserland&emc=rss&pagewanted=all

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GavinB
"Adding lanes or roads is a short-lived fix. Widen one highway, and drivers
from another will defect."

Thereby making both highways have less traffic. The fact that people come when
capacity is improved shows that you're lessening the load on other roads!

"Traffic jams are not, by and large, caused by flaws in road design but by
flaws in human nature."

Not accounting for human nature is a flaw in road design. Maybe it's just too
expensive to account for it, but traffic design is an exercise in
understanding driving habits.

Most of the facts in this article are right on and I bet the book is
worthwhile, but the writer of the article didn't seem to really think through
what he's saying. It's sad when good concepts get ruined by weenie-thinking.

~~~
rudyfink
I've always wanted highway response crews to come equipped with unfoldable
response screens. Something like a nice 20' screen which would block off the
view of the accident from the opposing lane. I've always thought a
considerable about of time, money, and perhaps life could be saved by such a
policy.

It was nice to finally see an article that explained why I don't see such a
thing.

~~~
antiismist
I thought about this, and I don't think it would work. From the response
crew's perspective, they want a massive traffic jam, because the cars are
moving slower and paying more attention. So the response crews who would have
to put up the screen would have an incentive to oppose it.

~~~
zenspider
I sorta agree, and I sorta disagree...

Here in Seattle I've been held up for over an hour on the 520 bridge because
of an accident THE OTHER DIRECTION. Having screens would prevent rubber
necking on the other side of the highway (with a large cement barrier in
between).

Also, I think you can do a lot to the screen itself to increase driver safety.
Make it 15' high and entirely yellow/black diagonal stripes and it'll catch
driver's attention and get them to slow down. TV and radio educational ads can
help too.

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mixmax
Interestingly the core problem of highway congestion is that drivers
decelerate faster than they accelerate.

An example: Person A slows down a little on the highway for some reason -
maybe she sees something on the side of the road, maybe her cellphone goes
off, it doesn't really matter. Person B behind her slows down a little as well
to keep her clearance, person C does the same and so on. Now person A speeds
back up to her original speed (when she is done talking on her phone, watching
stuff on the side of the road, or whatever) but she doesn't accelerate quite
as fast as she decelerated - this is perfectly normal behaviour - notice it
next time you take a trip in your car. Person B does the same thing when she
sees person A accelerate and so on. Before long you have a whole row of cars
that need to brake because the cars in front of them have decelerated quickly
and accelerated slowly. This is what causes most traffic jams on highways.

This is also why a traffic jam moves backwards on the road as time passes.

~~~
robg
Could it be any other way? Could you design a road to induce acceleration and
slow deceleration without affecting safety?

~~~
mixmax
A simple and effective way of dissolving a traffic jam is to keep going at the
same speed - let me explain:

You see congestion up ahead, and you slow down to, say, 40mph. This creates
some room in front of you in anticipation of the inevitable braking. You then
drive through the traffic jam at a constant speed with no acceleration or
deceleration, and the people behind you will have no choice but to follow (or
change lanes which is the weak point of the solution) What you will see at the
other end (if you could go back and look) is that you have dissolved the jam
because you have prevented people from decellerating quickly and accelerating
slowly.

Several people have tried this successfully and it works.

~~~
boredguy8
It's really fun when 3 or 4 people all know and do the same thing. It solve
the 'weak point' and once or twice I've been part of a 'team' that cleared a
jam that way. It's a weird sort of rush.

~~~
swdesignguy
This reminds me of an old episode of Scientific American Frontiers.

<http://www.pbs.org/saf/transcripts/transcript904.htm#5>

~~~
boredguy8
Thanks for the link. I believe it was this episode that influenced a lot of
how I drive (merging, staying slow but consistent in stop-and-go traffic, &c).
It should be required watching for new drivers.

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mhartl
Traffic jams may have complicated causes for any fixed number of cars on the
road, but it's worth noting that they don't often have traffic jams in rural
Kansas. The fundamental problem of traffic is that there are too many cars on
the road, and that's because road usage is priced too low. The predictable
result is queueing, i.e., traffic. Most of the fancy investigations into the
psychology of drivers, etc., are simply higher-order corrections to this basic
0th-order result.

~~~
mleonhard
Public transportation is the answer to traffic jams. If the government stopped
renting out street-side parking for artificially low prices then the cost of
parking would become a bigger incentive to use public transportation.

~~~
mhartl
Agreed. Pricing parking correctly would be one big step. A potentially even
bigger step would be to repeal the medallion laws that currently give taxis
weird cartel status in most cities. This would allow anyone to offer transport
for money, i.e., you could form jitneys
(<http://en.wikipedia.org/wiki/Jitney>). I secretly want to find a large city
with bad public transport (Los Angeles? San Jose?) and start a jitney company
---which, on its way to making billions, would solve the problem of urban mass
transit. (Talk about "Be good" and "Make something people want"...)

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mdasen
He's touched on some reasons, but definitely not all of them.

A big part of traffic is that communication doesn't happen - because it can't.
I can't tell the driver behind me "I'm going to be slowing down in 10 seconds,
get ready." Likewise, it isn't easy to convey to someone merging onto a
freeway that I'm going to let them in ahead of me so we both end up slowing
down so that we're both still in contention with each other until someone
takes the initiative.

Now, if only we had some way that cars could communicate with each other and
the road so that they could regulate speed and allow operations such as
merging as efficiently as possible. . .

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silentbicycle
People tend to act more selfishly in cars than they do outside of them, much
like many people do with the relative anonymity of the internet. I suspect it
is because drivers are in semi-protected pockets of their own space, and
they're essentially sitting still - there is not much they can do to discharge
physical frustration caused by traffic besides yelling, giving people the
finger, or driving more aggressively.

------
parenthesis
Isn't the real problem that a lot of people drive to, and then back from, work
at the same time?

~~~
dkokelley
The real problem is that a lot of people drive on the same roads at the same
time. What they're doing on the roads is irrelevant (although work is probably
the biggest cause of the demand for road usage. I assume you're attempting to
make a case for staggering work hours so "rush hour" is spread over a longer
time).

Roads are an interesting economic model. There are basically 3 primary
factors: current demand, current supply, and _price_. Price is especially
interesting because price isn't necessarily dollars (or your currency of
choice).

Price = Demand/Supply

So if demand goes up (rush hour, popular events, etc.) or supply goes down
(construction, accidents blocking lanes) then the price goes up. Part of the
price is paid in taxes that goes to build and maintain the road, the other
component of price is time. How much time will you spend driving. If it's rush
hour and there was a collision blocking the left lane and you're on your way
to a baseball game then the demand is pretty high, and the supply is pretty
low, so the price will go up. If this isn't a toll road, then the additional
price you're paying is 100% time. Of course the beauty is that you could in
theory take a toll road and pay in currency instead of time, although there
aren't always toll roads as options.

<sarcasm> I suppose the best solution is A: don't go anywhere, or B: get a
transporter like in Star Trek.</sarcasm>

~~~
demallien
Actually, I wonder if anyone out there has tried making toll-roads where you
pay more the more _time_ you spend on the toll-road, as opposed to the more
distance you travel. That would certainly provide a nice economic signal to
avoid congestion.

Of course, you'd also need to install a large number of speed cameras, to stop
the obvious method of gaming the system...

~~~
ks
I think that would lead to dangerous situations. You would see people
constantly changing lanes to try to maximize their speed. Accidents would
happen more frequently.

