

Traffic Hacks: How One Driver Can Vastly Improve Traffic - Mintz
http://trafficwaves.org/

======
RyanMcGreal
I changed my driving patterns after first reading this remarkable essay some
years ago. Now I follow what I affectionately call the "zen of driving", to
wit: leave a huge gap in front of me, drive at a constant speed where possible
[1], avoid using the brakes except in case of emergency, and so on.

On long driving trips through mixed traffic, I have made several observations,
some obvious and some surprising:

* Driving in congestion is no longer stressful. It just isn't. (Hence the "zen".)

* Dramatically improved fuel economy.

* It's possible to drive through even wildly erratic traffic (swinging from 100 km/h to 20 km/h) without ever touching the brakes. It becomes a kind of game. Manual transmission helps.

* Some other drivers seem to figure out what I'm doing, and they fall into place behind me at a reasonable distance. I've had people follow me for hundreds of kilometres this way.

* Even though you'd assume leaving a huge gap in front is an invitation for other motorists to cut ahead, they rarely do - especially in congestion. If they do, I just let them race up to the front of the gap and then fall back by a single car length to restore the same gap.

I absolutely swear by this driving method. It's easier on the car, easier on
the heart, and even serves to create a bubble of calm around you in an
otherwise turbulent flow of traffic.

\------

[1] Edit to qualify "drive at a constant speed". As I noted later, my speed
ranges dramatically based on the congestion level - what remains more or less
constant is the safe opening in front of me. Sorry for any confusion with my
original choice of words.

~~~
apotheon
That's not "zen" -- it's artificial regularity. Zen would be driving at what
feels like a natural speed, only adjusting that when circumstances dictate,
and "letting go" of your attachment to forward progress when something stands
in your way. Instead, you're driving at an artificially limited speed to try
to regularize your driving experience. You're tricking yourself into feeling
less frustrated by consciously eliminating frustration triggers from the
driving experience; a zen approach would involve simply choosing to feel less
frustrated by "realizing" that the frustration triggers really don't matter.

> Even though you'd assume leaving a huge gap in front is an invitation for
> other motorists to cut ahead, they rarely do - especially in congestion.

That's heavily dependent on time and place. I've lived in many different
regions, and done a lot of driving in those areas. I've noticed that the
tendency to fill in gaps is heavily dependent on local driving culture and the
specific demographics on the road at a particular time of day.

> I absolutely swear by this driving method. It's easier on the car, easier on
> the heart, and even serves to create a bubble of calm around you in an
> otherwise turbulent flow of traffic.

That may, to some extent, be an illusion. Some people are infuriated by other
drivers they perceive as holding them up -- which often includes people who
are "wasting" lane space by letting a gap of thirty car lengths lie unused in
front of them. Personally, I only get annoyed with such people when they try
to keep other people from filling that gap, because as far as I'm concerned a
steady gap (given a steady general traffic speed) creates irregularities in
grouping through which ambient traffic can accelerate itself, but people who
maintain a huge gap then rush to block out people who want to move into it are
increasing the danger of driving and doing nothing to help improve the flow of
traffic.

~~~
RyanMcGreal
>That's not "zen" -- it's artificial regularity.

Please see my edit in my original post to clarify what I meant to write. In
fact my speed ranges up and down based on the level of congestion, whereas the
safe buffer I maintain in front of me remains constant - and by safe I mean
long enough that I don't have to use my brakes when traffic slows.

As for my use of "zen", don't read too much into it. It was just a tongue-in-
cheek reference to the fact that I stopped trying to fight the flow of traffic
and instead simply pass through it as peacefully as possible.

>That's heavily dependent on time and place.

My observations are limited to highways in Ontario, Quebec, New York State,
Pennsylvania, and Massachusetts.

>I only get annoyed with such people when they try to keep other people from
filling that gap

Hey, man, you're welcome to it. Blocking another driver from filling the gap
would mean accelerating to close it, which kind of defeats the purpose of
maintaining it.

~~~
itistoday
I'm a Zen Master, I have the degree to prove it. Your use of the term has been
approved by the ZCUZ (Zen Committee On The Use Of "Zen").

~~~
itistoday
Children these days have no respect for Zen Masters.

~~~
apotheon
Is that self-referential?

~~~
itistoday
No, at least I certainly did not mean it to be. ;-)

The original comment, for those that don't get it yet, was a stab at
apotheon's comment. It was an attempt to avoid the argument of "what is Zen"
before it gets out of hand, as it's been known to do on other sites.

If you're curious, an example: <http://zenhabits.net/2007/01/why-zen-
habits/#comments>

------
mrshoe
This man is a saint. For years I've wished more people understood these
principles. Instead, I get drivers who are angry at me for leaving a big space
in front of my car. If only I pulled up right behind the car in front of me,
they'd be 60 feet closer to their destination!!

I wish more people would check this site out. Traffic is a _real problem_ that
wastes billions of taxpayer dollars and hours on the road every year.

Another idea to make the roads better: lane-specific _minimum_ speeds. Think
about it. It would actually solve a ton of common traffic problems.

~~~
antdaddy
Another problem is drivers who insist on driving in the left lane at all times
and refuse to move over. IIRC, the left lane used to be referred to as the
'passing' lane...

~~~
axod
In the UK it still is, and passing on the left is illegal. I like that system
more that all lanes equal.

~~~
rdtsc
So if there is a slow car there, what do you do? Does everyone wait behind
them until they turn/exit or decide to switch lanes?

~~~
axod
If there's a slow car in the outside lane, and they're not making any attempt
to overtake anything, you generally flash them until they move over. They are,
after all, breaking the law.

~~~
dgallagher
What if a car is in the passing lane doing the speed limit? Asking them to
move out of the lane so another driver could pass by speeding, breaking the
law, doesn't make much sense either.

~~~
axod
It's a grey area, although usually accepted that 90% of drivers drive faster
than the speed limit anyway.

If it's a 70 limit, and someone is in the passing lane doing 70, you'd still
flash them.

------
zck
Some Japanese scientists did a study to show how traffic jams can appear of of
nowhere. They told 22 drivers to drive in a circular path at 30 km/h. A
traffic jam appeared, and moved backward. The video is here:
<http://www.youtube.com/watch?v=Suugn-p5C1M>

~~~
kyro
It's not 'out of nowhere.' It's because we're humans. We're paranoid and
reactionary. You wouldn't see that with robots.

~~~
randomwalker
Cynical much? How about it's because we have bounded cognitive abilities,
limited perceptive accuracy and slow reaction times?

~~~
dkarl
You're forgetting the natural caution and fearfulness that protect us from
depending too much on our limited abilities when safety is at stake.

------
barrkel
Ever since I can remember, I've always thought this was obvious, a product of
random slowdown being amplified by reaction time delay. Motorway pileups are
well known to be exacerbated by close driving, because each subsequent driver
has to brake harder and harder to stop. Jams are just a less dramatic form of
the same thing.

------
jimbokun
"WHY must a bottleneck develop at a merge zone? Well, obviously because
there's too many cars on one road. And because everyone must take turns slowly
merging together. WRONG! Wrong wrong wrong. Even during extremely low-traffic
conditions, everyone still takes turns, yet everyone merges as a high speed
flow,like a zipper. A bottleneck never appears."

New York city drivers are really excellent at the zipper merge thing. While
living there, I got really used to not having to slow down much at merge
points. Everyone just drove at a decent speed using all available lanes then
smoothly merged at the point where the lane was closed.

Moving back to Pennsylvania, people start queuing up in one lane a mile before
the merge point, and traffic grinds to a stand still. This is insane. Usually,
though, if you do the sane thing and use the other lane up to the merge point,
you can get in without trouble.

Maybe I was one of the early mergers before I lived in New York, and have just
blocked it out of my memory. Now, though, seeing it happen really grates on my
nerves. One of many reasons I'm glad I hardly ever drive anymore. :)

------
devin
I've been driving like this ever since I heard a show on Wisconsin Public
Radio where they interviewed a traffic researcher. One thing that is _not_
true, however, is that "cheaters" are always wrong.

For instance, there is significant research that suggests in a 2 lane
situation where both lanes must merge into one single lane (road work ahead,
for example), it makes more sense for both lanes to proceed uniformly toward
the point where they must merge. Most people would assume this would cause a
deadlock at the point where the merge occurs, but it doesn't. When both lanes
are allowed to proceed without switching lanes towards the point where they
both must merge, they will achieve far better results than if they were to
organize into a single lane prior to that point.

This makes people /really/ angry. Once, when there was approximately 2 miles
notice for road work, I stuck with the right lane and did not merge into the
left lane like everyone else. I actually had a large pickup truck attempt to
cut me off from proceeding in an EMPTY lane.

Of course, this only holds when there is an inevitable traffic jam. When it
comes to /avoiding/ traffic jams, you are better off maintaining distance to
allow other drivers to merge.

------
krschultz
It saves a lot of gas too. I've always tried to get through stop and go
traffic smoothly without using the brake, but I always did it for my own gas
consumption. I never had this macro look at it.

~~~
seanc
Especially if you drive a standard transmission. Staying off the brake makes a
huge difference, and makes for less clutching as well. For bonus points, you
can put the car in neutral while coasting, although some don't think that's
safe.

~~~
eru
On modern cars with manual transmission, the motor is powered with some gas
when it is not engaged. However when you leave it engaged an just don't push
the pedal, no gas is needed. (Although the motor brakes somewhat. I don't know
which effect is stronger.)

------
tptacek
Doesn't this imply that cities could alleviate traffic pathologies by hiring
people to drive carefully down the highway?

~~~
designtofly
This was the focus of a short video a group of college students made a few
years ago, "A Meditation On the Speed Limit."

<http://video.google.com/videoplay?docid=-5366552067462745475>

~~~
kingnothing
Is that the video in Atlanta where they drive side by side around I-285 at the
speed limit of 55 mph? It's an interesting social experiment, but I'm
surprised none of them were driven off the road. Traffic on the left on 285
generally moves at 70 - 80 mph here.

------
noodle
i think its interesting that i used to drive like this site describes for the
exact reasons it talks about. and now i don't/can't. the difference? i moved
to atlanta.

rush hour drivers here operate under a greedy algorithm. they see an opening
that will allow them to speed up or gain extra distance immediately, and
they'll take it, for no other reason than to be going faster right now, to be
farther down the road right now.

and that includes eating up my buffer zone, forcing me to break/stop, killing
my flow optimization.

~~~
zngtk4
That (in addition to the fact that everyone lives in the suburbs) perhaps
provides some of the explanation for why Atlanta rush hour traffic seems to be
some of the worst in the country, despite having more lanes and a smaller
population than cities that have better traffic.

~~~
apotheon
I have had to commute on two of the top ten worst rush hour stretches of
highway in the country (and they're within a few miles of each other in
southern California, on the 91 and I-10). Noodle is exactly correct that such
driving "cultures" do exist, and they make this consciously regularizing
driving style worse than useless.

------
kyro
I'm a fast driver, and one thing I will never understand are those who will do
anything and everything to box in a fast driver, or to prevent them from
cutting into a lane and taking off. I see fast drivers as excited molecules,
looking to escape. What often happens when a fast driver is being blocked is
they'll switch lanes back and forth, looking for their escape, creating this
wave of hesitation, causing this big low speed anchor to form.

Someone driving fast won't suddenly stop the speeding after being blocked.
Just let them go!

~~~
ynniv
I am a fast driver, but in traffic I switch to wave abatement. It seems only
logical to help the system when there is no way to personally benefit. (Except
that moving to the right-most non-merging lane will help you avoid waves and
move faster.) My prioritized rules of the road are:

    
    
      1) go whatever speed you like
      2) empty lane to your right? move right
      3) no car in front of you and a car behind you? move right as soon as possible
      4) slower car in front? move left if you can
    

These simple rules cover most situations in a way that benefits everyone
involved. They do not cover some minority cases: aggressive tailgaters and
high relative lane speeds (I leave a buffer lane if > 10 mph and no cars
behind me).

------
imgabe
I read this a while ago and I try to do it whenever I find myself in traffic.
If nothing else, it is immensely less frustrating to drive a constant 15mph
than to drive 30mph half the time and be at a complete stop half the time.

------
masomenos
While I have not conducted any format experiments in the efficacy of the
advocated driving method, I can report that it's far more relaxing than
tailgating. Give it a try!

------
tjic
When I accidentally end up on Rt 128 at rush hour, I do this.

(I note that I was on a mailing list with a bunch of relatively smart people
once, and I mentioned what I did - and even among the smart folks there was a
lot of outrage because I was driving "wrong" or "stupidly".

That reaction contributed to me leaving the list shortly thereafter. )

~~~
cema
How happy I am to live (and work) at the portion of Rt 128 which is separate
from I-95!

But every time I go down to Boston, or far away to other urban areas, I can
never keep the distance that I want because someone would certainly cut in. So
I increase the distance again, to avoid tailgating, then another guy gets in
between us, etc, etc. And so we have a peloton of cars moving at 65+ mph a few
meters away from each other. Not too pretty.

~~~
apotheon
Nice use of "peloton".

------
zngtk4
Interesting, my instinct has always been to try to "punish" the cheaters by
preventing them from merging in, thinking that this would discourage this
behavior. But I can't really stop this, and the article provides a good
explanation for why you might as well just let people merge in front of you.

~~~
swolchok
The problem is that allowing merges incentivizes zooming ahead in the merge
lane, which should result in there still being drivers who can't merge,
creating the jam. I don't have a good solution for this.

~~~
zngtk4
To an extent I think you're right and some people will do it regardless. On
the other hand, smoothly flowing traffic creates an incentive to not zoom
ahead in the merge lane. There's less of a feeling of a need to cut ahead and
people don't seem to do it as much when there isn't already a jam. (That is,
the jam provides an incentive to cut in front of everyone)

And if people were to implement this strategy, the provided space gives an
incentive for those zooming ahead to merge a little sooner rather than risk
waiting half a minute for someone to let them in right at the exit. It's been
my experience that most of the "cheaters" will merge a little sooner if
there's space rather than zoom up right to the end. They'll still be passing
you, which is IMO aggravating, but at least things will move a little sooner.

------
chr15
For anyone else fascinated by traffic patterns and driver behavior, I
recommend reading Traffic: Why We Drive The Way we Do and What It Says about
Us

The author goes into fascinating detail about driver psychology and discusses
similar ideas like those mentioned in the essay.

Link to book: [http://www.amazon.com/Traffic-Drive-What-Says-
About/dp/03072...](http://www.amazon.com/Traffic-Drive-What-Says-
About/dp/0307277194/ref=sr_1_1?ie=UTF8&s=books&qid=1251250678&sr=8-1)

------
Mintz
I've actually done this on my way to/from work, and it makes a legitimate
improvement in my commute.

------
tezza
_How One Driver Can Vastly Improve Traffic_

Yes, but that one driver is _never_ the guy in front of you.

------
iigs
I respect this guy's patience, but the primary reason that one car can make
such a big difference in this case is because 520 (one of the most important
commuter roads in the Seattle area) is just two lanes in each direction. One
car on a three lane road will just be passed.

The counter-point to this, in my opinion, is that at some point psychology
comes in to play and you have people starting to get aggressive and angry
because of a few people forming a "rolling-road-block". It's not rational but
it definitely happens.

I would support 3PM-7PM dynamic speed limits on 520W toward the bridge. If the
speed was brought from 60 (just past 405) to 30 as you approach the bridge it
could probably keep things moving smoothly through the traffic burst.

------
huherto
I read this site a few years back and I've done a bit experimenting. I'm
convinced that leaving space in front and avoiding sudden changes on speed are
really helpful. Some times I have even seen traffic jams disapear if I leave a
lot of space in front.

------
nalbyuites
This essay should appear as a Public Service Broadcast through all media
outlets.

------
apotheon
My biggest complaint about this is that it's going to give many people who
don't _actually_ help traffic, and just drive slowly, feel self-righteous
about their driving habits. Yes, in some circumstances this driving style can
help traffic; no, it doesn't mean that driving 15MPH slower than ambient
traffic is justified "for the greater good", especially if you're the type who
jealously guards the thirty car lengths in front of you, accelerating to keep
people from changing lanes in front of you.

------
steamer25
Nice, patient guy but there's a better way yet if you can afford to gamble
with your time a bit (don't try this if you can't afford to lose a little
time).

When confronted with a single backed up lane, use the uncontended lanes to zip
to the front of the wave and merge in _at speed_. Maintaining speed is
important. If you don't find an opening, you'll have to abort and find another
route to your destination.

The up-side is that this almost always pays off and you waste little time
slowed by traffic or slowing others. The reason is because many people who
queue up resign to the monotony and pull out their phone or their air drums,
etc. They pay enough attention to brake consistently but not enough to
accelerate as soon as is possible.

The vast majority of the time, you can slip in front of one of these
'sleepers' before they notice the opening or have fully accelerated. Because
of inertia, they will go through an acceleration period where you pull away
from them leaving them a very sufficient gap.

Another way to look at this is using the available real-estate to ascertain a
proper zipper-merge. If done right, you wait less and no one gets stuck behind
you. This is especially useful if you commute five days a week--the payoffs
over time are well worth the occasional crap out.

~~~
devin
I take issue with your theories. The "payoffs" you allude to do not exist.
Your "zipper-merge" costs you gas money, and if you took the time to watch the
video, you'd realize that you are considered a "cheater". Cheaters feel better
about having gotten in front, but what they don't realize is that the
"sleeper" is providing a way for cars to merge, thus alleviating the jam in
the first place. All you're doing is typical busy-body traffic maneuvers that
soothe your rattled frame, but do nothing to actually get you to your final
destination any faster. The difference between maintaining adequate distance
and doing your patented "zipper-merge" have been proven to shave at the _most_
, a minute and a half off of your commute. Even if you do this five days a
week, you're saving roughly 8 minutes. If you think that's worth it, then you
should also be aware that the vast majority of accidents occur while changing
lanes.

~~~
Dove
Actually, this study
(<http://ops.fhwa.dot.gov/wz/workshops/accessible/McCoy.htm>) lends credence
to the claim. Late merges have better throughput than early merges when
encouraged by traffic signs and uniformly adopted.

The study does not directly address the effect of "cheating" late merges which
can create waves, but did note that traffic signs which strongly encouraged
early merging by everyone increased overall transit time through construction.
That suggests that the default case is better.

That makes a little sense to me: a single lane can bear less traffic, so
extending the amount of distance everyone has to spend in a single lane might
result in higher latency overall, if not necessarily lower throughput.

------
boredguy8
"Constant velocity" applies to lane changes, as well. I hate when people are
going 70mph and slow down to the 55mph of the car in front of them, THEN
change lanes. No, change lanes as you're coming up on them so that you
maintain a constant velocity.

Related to this is the need to "stay right". Especially in CA, some of my
fastest travel happens in the far right lanes because people think of lanes as
a "speed" rather than a "function", and so the right lanes are empty while the
left lanes are crowded and slow.

The number one lane is not the "fast" lane, it's a "passing" lane. Guess what?
The number two lane is a passing lane, too. If you're not passing anyone, you
should be on the far right side of the road.

------
TravisLS
This is a representation of classic game theory. If all participants cooperate
to drive as described, the traffic clears. If nobody else helps to open up
space, however, you will personally arrive at your destination slower by
driving passively, even though many others behind you will benefit. And since
this type of driving requires some degree of altruism, you can pretty much
rule it out as a realistic outcome without introducing another constraint (eg.
as mentioned in the article, state troopers merging into traffic and forming a
rolling barricade).

~~~
jcl
However, if _everyone_ carried 10-15 extra car-lengths ahead of them, the
total capacity of the road would be greatly diminished; you would just be
moving the jam to the on-ramp.

The peak performance of the system is actually a mix of altruism and
selfishness.

~~~
masomenos
That's a fallacy, addressed by the site -- in short, the benefit gained by
minimizing jams more than offsets the increased space between vehicles.

~~~
jcl
I think you may have misunderstood my point, which is that peak performance is
attained when a few drivers drive altruistically (as the author does) and the
rest drive "normally". If all drivers choose the same behavior (all altruistic
or all normal), then the system doesn't work as well. This is interesting from
a game-theoretic standpoint.

The author says much the same thing on his FAQ page:

 _If EVERY driver was to constantly maintain a HUGE space regardless of speed,
then it would probably cause problems. The merge-zones might stop jamming, but
the capacity of major highways would be reduced. On-ramps would become choked
as traffic backed up into them, and there would be slowdowns extending far out
into the countryside._

It is, of course, a purely theoretical problem, since there is no shortage of
non-altruistic drivers.

------
bvanevery
I completely agree with the moving wave! I have pondered this very same
pattern myself. I'm excited to see it documented and shared on the web.

Taking this "zen" driving a step further and imagining an ideal world of cars
that never break down on the highway and where the process of merging onto and
exiting from a highway could be scientifically mastered such that the speed of
the nearby cars is at most nominally affected, it is not inconceivable that
cars could travel at speeds far beyond what is considered safe today.

------
poltergeist
My friend and I have designed, in our 6th semesters, a 8085 microprocessor
based, congestion-aware traffic control for crossroads.

The system uses switches on the roads ( replaced using RFID or other sensors
placed on the ground or at the sides of the roads ), that detect the load on
each path and route traffic accordingly.

Not much, but it worked like a charm !!

------
mattmcknight
Makes me think of Drum-Buffer- Rope from Theory of Constraints. Maybe we need
a pull system for roads. There are a few onramps on criminally undersized (due
to nimby nutsos) highways in my area where a traffic light limits flow onto
the road at busy times- smart. Then the same people put in stoplights at the
ends of the offramps, backing traffic up onto the highway.

------
simplegeek
BTW, sorry if this sounds off-topic, do you know any good books/articles on
Traffic? I'm very much fascinated by this too. Thanks.

~~~
tptacek
Not even close to off-topic. Traffic problems (and queuing theory) have a long
history in CS, and the related problems have applications all over the place.

~~~
simplegeek
Can you recommend any good books related to Traffic issues for a beginner and
intermediate? Thanks.

------
VBprogrammer
While I find letting the 'cheaters' in grates too hard on my soul I alway try
to practice driving at the average speed and avoiding using the brake. If for
no other reason than to avoid wear on the car (in the UK most cars are still
manual and so each start is a tiny bit more wear on the clutch as well as the
brakes).

------
aoeu
Kinda related and interesting/amusing - "This Guy Can Get 59 MPG in a Plain
Old Accord. Beat That, Punk.":

[http://www.motherjones.com/politics/2007/01/guy-can-
get-59-m...](http://www.motherjones.com/politics/2007/01/guy-can-get-59-mpg-
plain-old-accord-beat-punk)

------
ThomPete
One has to wonder whether same principle can be applied to economics.

I.e. that continous and moderate spending instead of savings somehow keeps the
wheels moving in the economy.

------
mildweed
This works, but the trouble comes when some guy in a big truck starts heavily
tailgating you and flipping you off.

~~~
ynniv
That would be unfortunate, since a heavy truck has the most to gain by not
changing speed.

------
erlanger
If you want to help traffic, stop hitting your damn brakes so much. Brakes are
for strong deceleration, and most deceleration in traffic can be handled by
letting off the gas. Once you get good at this, follow as closely as possible
in a traffic jam without applying your brakes.* There's nothing better a
skilled driver can do to alleviate a traffic jam. The jam is physically
shorter and people behind you are less likely to apply their own brakes as a
result of these measures.

* This has the added benefit of making for a smoother ride, which also encourages those behind you to ease off the brakes.

~~~
BRadmin
Driving in Los Angeles, this is exactly what I do... I'm convinced that most
traffic jams are caused by people needlessly applying their brakes and slow
cars clogging the fast (far left) lane.

