OLD EMAIL ABOUT 'TRAFFIC WAVES'

Q: What makes you such an expert?!

A: Nothing, I am not an expert. I'm just a guy who is fascinated by the "traffic physics" I see during my commutes. I have no reputation to defend, so I have no inhibitions about posting my observations and reasoning, flawed though it might be. All the material on this website is nothing but speculation and "crazy experiments" performed by a total amateur. For info from actual experts, try some of these links.

From: Beaty, William J
To: vortcor-list
Subject: traffic nonlinear dynamics
Date: Friday, February 14, 1997 5:13PM

ppearson@netcom.com wrote:

> A fascinating idea. Has anybody investigated the collective
> phenomena that can emerge from a string of cars all using the
> same braking algorithm? There could be some very interesting
> engineering work there.

> I remember a guy describing the frustration of driving the last
> tank in an Army convoy. Although the algorithm was simple (maintain
> a certain distance from the tankk in front of you) and the
> boundary conditions benign (the lead tank maintains a near-constant
> speed), he says the driver at the tail of the convoy alternates
> between panic braking and frantic acceleration.

But human drivers DO all use approximately the same braking algorithm. When the car ahead of us jams on its brakes, we have to do the same. And the resulting "emergent phenomena" is very interesting.

I've made spontaneous field-observations of such things. ;)

A couple of years ago I was in a chain-collision on I-5 caused by a sudden downpour and panic braking of several people at once. I think I was the 4th to collide, and there were 3 collisions behind me. I suspect that the decrease of reaction time window is cumulative, until those at the tail of the chain cannot avoid collision. It's as if the moving line of vehicles is an energy-storage medium, and when the chain is given a large wave-pulse which induces nonlinear behavior, a soliton wave is created which travels backwards along the chain for as long as it can find fresh cars to swallow. The moral of this tale: if your view is unexpectedly obliterated by a downpour, panic braking will get you rear-ended.

Something I've been long been wondering about. Bad traffic conditions often seem to be caused by *interactions* between the "behavior algorithms" of the individual drivers. The same roads could handle more traffic if drivers had different behavior. But rather than requiring all drivers to undergo intensive training classes, perhaps there is another route to improvements: lubrication. Insert a certain small percentage of drivers who have radically different behavior than the "bulk medium". This "dopant" might have major effects on the collective behavior of the traffic, just as tiny amounts of dopant have enormous effects on the properties of semiconductor materials.

Even more musings: in nonlinear systems, it's possible to control large scale chaos with tiny "taps." In auto traffic, maybe it would be possible to have a single "dopant" car keep track of the collective behavior, and then exert long range modifications on the traffic by taking appropriate small actions which are determined by ongoing computer simulations, feedback, etc. A single heavily-computerized car would go surfing in the phase-space of traffic, and it would force the smooth-flow behavior among all the surrounding normal humans. Remember, single butterfly flap can *stop* a hurricane too. Maybe it can stop a traffic jam.

(As a hobby I drive through the I-5 stop & go traffic jams at just the average speed, just so that I can look in my rear-view mirror and see the lack of traffic-condensations in the miles of lane behind me, as compared to the periodic clots in adjacent lanes. Fun stuff!)

(((((((((((((((((((( ( ( ( ( (O) ) ) ) ) )))))))))))))))))))))
William J. Beaty DESIGN ENGINEER
beatywj@ch.etn.com INDUSTRIAL PHOTOCONTROLS
EATON/CUTLER-HAMMER Everett, WA 206-353-0900

Subject:      Re: Traffic Waves
From:         bbeaty@microscan.com
Date:         1998/05/23

In article <6k2r7o$5rp$1@jetsam.uits.indiana.edu>,
  glhansen@copper.ucs.indiana.edu (Gregory Loren Hansen) wrote:
>
> In article <35648AC4.ED39B484@ix.netcom.com>,
> Tom Carlson   wrote:
> >I wonder how many rear-enders have been caused by some
> >smug little man thinking he was protecting society from fast drivers?
>
> Probably none, if people followed the "two-second rule" from driver's ed
> and obeyed the speed limits.  No matter how fast you're going and how fast
> the guy in front of you is going, there should *always* be enough room
> between you to avoid a collison.  Of course that means someone might merge
> in front of you, but safety has its price.


A couple of times I was the "smug little man."  See if you think it was 
worth
it:

After driving through many stop/go traffic waves at rush hour on 520 in 
Seattle, I decided to try something.  On a day when I immediately started 
hitting these "waves", I decided to (gasp!) drive slow.  Rather than 
rushing ahead with everyone else, only to come to a halt, I decided to try 
to hit the average speed of the traffic.  I let a huge gap open up ahead 
of me, and timed things so I was arriving at the next "stop-wave" just as 
the last red brakelights were turning off.  I did this for maybe half an 
hour while approaching the city.  Finally I happened to glance at my 
rearview mirror and saw an interesting sight.

It was dusk, the headlights were on, and I was going down a long hill to 
the bridges so I had a view of miles of highway behind me.  In the other 
lane I could see maybe five of the trafficjam stop-waves.  But in the lane 
behind me, for miles, TOTALLY UNIFORM DISTRIBUTION.  I hadn't realized it, 
but by driving at the average speed, I had been "eating" traffic waves.  
My single tiny car had erased miles and miles of stop-and-go traffic.  
Just one "dopant atom" had a profound effect on the particle flow.

This leads me to see that traffic waves are caused by our need to rush 
ahead whenever given the chance, and our need to pack ourselves densely 
when we meet a row of stopped cars.  Because we all behave this way, 
traffic waves form.  If we intentionally behaved differently, then traffic 
waves (and perhaps traffic jams themselves) beome impossible.

((((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))
William Beaty                                 bbeaty@microscan.com
Software Engineer                             http://www.microscan.com
Microscan Inc.                                425-226-5700 x1135
                                              Renton, WA

Subject:      Re: Traffic Waves
From:         Tom Carlson 
Date:         1998/05/23

bbeaty@microscan.com wrote:

> In article <6k2r7o$5rp$1@jetsam.uits.indiana.edu>,
>   glhansen@copper.ucs.indiana.edu (Gregory Loren Hansen) wrote:
> >
> > In article <35648AC4.ED39B484@ix.netcom.com>,
> > Tom Carlson   wrote:
> > >I wonder how many rear-enders have been caused by some
> > >smug little man thinking he was protecting society from fast drivers?
> >
> > Probably none, if people followed the "two-second rule" from driver's ed
> > and obeyed the speed limits.  No matter how fast you're going and how fast
> > the guy in front of you is going, there should *always* be enough room
> > between you to avoid a collison.  Of course that means someone might merge
> > in front of you, but safety has its price.
>
> A couple of times I was the "smug little man."  See if you think it was worth
> it:
>
> After driving through many stop/go traffic waves at rush hour on 520 in
> Seattle, I decided to try something.  On a day when I immediately started
> hitting these "waves", I decided to (gasp!) drive slow.  Rather than rushing

The jam was there when you started.  Going the average speed of the jam
fixed t he problem behind you.  Had there been no jam, going slow in the
left lane would have started one. 

By your argument, you should drive at the average speed of the other cars
in yo ur lane, which means, go faster in the left lane, or get out of the
way, which was my point. 

Obviously when a jam starts, all bets are off, because all lanes move at
the sa me (average) speed, for the most part.  As long as you proceed at
the average spee d of the other cars, you aren't inconveniencing anyone,
and, by your own observations, might even be helping things.  It's when
you go slower then the average speed of the other cars in your lane that
you foul things up. 

> This leads me to see that traffic waves are caused by our need to rush ahead
> whenever given the chance, and our need to pack ourselves densely when we
> meet a row of stopped cars.  Because we all behave this way, traffic waves
> form.  If we intentionally behaved differently, then traffic waves (and
> perhaps traffic jams themselves) become impossible.

I think I've heard of proposed traffic control "cruise control"
strategies, whe re you would put your car in "cruise control" by law in
metropolitan areas.  The speed of the "cruise control" would be determined
by a central computer, and broadcast to all the cars by radio.  I suppose
you would still override with yo ur brake, but never touch the throttle
pedal.  Perhaps an onboard computer in the car would work to maintain your
average speed at setpoint, going faster for a while, taking into account
any braking you did. 

--
      Tom Carlson                 Vancouver - WA - U.S.A.
Washington. Where the men are wet, the sheep are wet, the trees are ...
   _________________________________________________________________




Subject:      Re: Traffic Waves
From:          (William Beaty)
Date:         1998/05/25

Tom Carlson (extol@ix.netcom.com) wrote:
: The jam was there when you started.  Going the average speed of the jam
: fixed the problem behind you.  Had there been no jam, going slow in the
: left lane would have started one.  By your argument, you should drive at
: the average speed of the other cars in you lane, which means, go faster
: in the left lane, or get out of the way, which was my point.

Very true.  In normal highway driving, it's rude to sit in the left lane
going slow.  It also makes people pass on your right, which can be
dangerous.

: I think I've heard of proposed traffic control "cruise control"
: strategies, where you would put your car in "cruise control" by law in
: metropolitan areas.  The speed of the "cruise control" would be
: determined by a central computer, and broadcast to all the cars by
: radio.

That would certainly work.  Here's a sillier, "manual" way of doing it.

When a big traffic jam develops, have a row of state trooper cars form a
moving barrier maybe 10 miles upstream from the jam, then drive at a low
speed.  Soon a huge empty space would open up ahead of the slow cop cars,
and the traffic flow that feeds the jam would dry up.  The speed of the
barrier cars would be adjusted so that the last of the jam was gone just
as they (and their trailing miles of evenly-spaced traffic) arrived.  Just
like "eating" traffic waves, but a single huge empty space cancels out a
major multi-lane traffic jam, and nobody can leak past the slow cars which
creates the empty space.

This of course could be performed by any group!  It would be cool to see
some traffic-helicopter timelapse footage of such a thing.  Probably
illegal, so if you and your fellow barrier-car drivers end up in jail for
illicit traffic-modification experiments, don't blame me!

--
((((((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))))
William J. Beaty                                  SCIENCE HOBBYIST website
                                  amasci.com
EE/programmer/sci-exhibits          science projects, tesla, weird science




   _________________________________________________________________
   
Subject:      Re: Traffic Waves
From:         glhansen@copper.ucs.indiana.edu (Gregory Loren Hansen)
Date:         1998/05/23

In article <6k55tu$ahh$1@nnrp1.dejanews.com>,   
wrote:
>could see maybe five of the trafficjam stop-waves.  But in the lane behind
>me,  for miles, TOTALLY UNIFORM DISTRIBUTION.  I hadn't realized it, but by
>driving at the average speed, I had been "eating" traffic waves.  My single
>tiny car had erased miles and miles of stop-and-go traffic.  Just one "dopant
>atom" had a profound effect on the particle flow.

Woah!  I don't know what the people behind you thought, but just knowing
that this happened made it all worthwhile!  One little car regulating all
of that rushing traffic.  I really never guessed it could happen.





Subject:      Re: Traffic Waves
From:          (William Beaty)
Date:         1998/05/25

Gregory Loren Hansen (glhansen@copper.ucs.indiana.edu) wrote:
: >me,  for miles, TOTALLY UNIFORM DISTRIBUTION.  I hadn't realized it, but by
: >driving at the average speed, I had been "eating" traffic waves.  My single
: >tiny car had erased miles and miles of stop-and-go traffic.  Just one "dopant
: >atom" had a profound effect on the particle flow.

: Woah!  I don't know what the people behind you thought, but just knowing
: that this happened made it all worthwhile!  One little car regulating all
: of that rushing traffic.  I really never guessed it could happen.

It was really amazing.  It only works when traffic is dense enough that
people can't easily change lanes.  In other words, the traffic essentially
changes into a bunch of separate one-lane roads, and passing only happens
rarely.  But then, the traffic waves and traffic jams can only form under
those conditions, otherwise all the cars would just cut around the jam.

The central idea: a single car can have vast effects, but only on the
traffic which follows it.  This sets up an interesting philosophical
system: you can't improve your own situation, but you can give aid to
those behind you.  If most of us act as "normal" competitive assholes, we
wreck traffic for everyone.  But if we take an altruistic stance, then
those ahead of us might improve our situation, while we improve things for
those behind.

Fortunately it doesn't take very many altruists to make serious
alterations in the traffic patterns.  They act like lubricant, and only a
small percentage of "lubricant" molecules is needed.

A single car, if it builds up an empty space ahead of it, can use that
empty space to take a big bite out of the rear end of a traffic jam.  If
just a few cars repeated this procedure, a traffic jam would be eaten (it
would be transformed from a short section of stalled traffic into a long
section of slow traffic.)  Do-it-yourself amateur traffic engineering.

--
((((((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))))
William J. Beaty                                  SCIENCE HOBBYIST website
                                  amasci.com
EE/programmer/sci-exhibits          science projects, tesla, weird science


   _________________________________________________________________
   
Subject:      Re: Traffic Waves
From:         conover@tiac.net (Harry H Conover)
Date:         1998/05/23

bbeaty@microscan.com wrote:
: This leads me to see that traffic waves are caused by our need to rush ahead
: whenever given the chance, and our need to pack ourselves densely when we
: meet a row of stopped cars.  Because we all behave this way, traffic waves
: form.  If we intentionally behaved differently, then traffic waves (and
: perhaps traffic jams themselves) beome impossible.
:

I only wish that you had cross-posted to the entirety of the newsgroups.
You've given a vivid description of what traffic engineers already know,
that the traffic-jam stop-waves are almost entirely the result of drivers
ignoring basic headway-flow principles.

I've tried doing the same thing here in the Boston area, but here it's
a lost cause. To Boston drivers, a car in front of them is a challenge,
and to save five car-lengths they will resort to extremes in driving!
This is the principal cause of Boston's legendary stop and go traffic
patterns.  Drive Route 128 on most days and you'll know what I mean.

My only question is this: Why has driver education been largely
deleted from public education?

                                            Harry C.
   _________________________________________________________________
   _________________________________________________________________
   
Subject:      Re: Traffic Waves
From:         jmccarty@sun1307.spd.dsccc.com (Mike McCarty)
Date:         1998/05/28

In article <6kig3k$s49@sun001.spd.dsccc.com>,
Mike McCarty  wrote:
)In article <6k2r7o$5rp$1@jetsam.uits.indiana.edu>,
)Gregory Loren Hansen  wrote:
))In article <35648AC4.ED39B484@ix.netcom.com>,
))Tom Carlson   wrote:
)
)[snip]
)
))>I wonder how many rear-enders have been caused by some
))>smug little man thinking he was protecting society from fast drivers?
))
))Probably none, if people followed the "two-second rule" from driver's ed
))and obeyed the speed limits.  No matter how fast you're going and how fast
))the guy in front of you is going, there should *always* be enough room
))between you to avoid a collison.  Of course that means someone might merge
))in front of you, but safety has its price.
)

Oh, also I once read an interesting paper which used some reasonable
mathematical models to show that the "two second rule" *causes*
unexplained slowdowns and collisions.

Mike
--
----
char *p="char 
*p=%c%s%c;main(){printf(p,34,p,34);}";main(){printf(p,34,p,34);}
This message made from 100% recycled bits.
I don't speak for DSC.         <- They make me say that.
   _________________________________________________________________
   


Subject:      Re: Traffic Waves
From:         sbenett@NOJUNKgate.net (Stephen Bennett)
Date:         1998/05/22

In article <35648AC4.ED39B484@ix.netcom.com>,
   Tom Carlson  wrote:
>William Beaty wrote:
>
>> I've added a crude little animation to my TRAFFIC WAVES article.  If you
>> haven't seen this before, check it out:
>>
>>    http://trafficwaves.org

>I've always been frustrated with those people that get in the left lane,
>and go slow, no doubt patting themselves smugly on the back that they are
>keeping people from speeding.  Their actions contribute to the traffic
>problem more then they know, as your wave equation shows.
(snip)
>  I wonder how many rear-enders have been caused by some
>smug little man thinking he was protecting society from fast drivers?

Yes, increased rear-enders, and those accidents that will take place as 
frustrated drivers weave around the slow pokes in the fast lane. There is 
certainly a higher risk of a miscalulation by a driver trying to squeeze 
in front of one of these smug or indifferent drivers. Not only do I feel 
they increase the chances for an accident by other drivers, but they 
*markedly* enhance their own probability of being a participant. I can't 
understand that lack of concern for their own selfinterests.

I've often noticed that these slower drivers (apparently on cruise 
control) refuse to either backoff or speed up to pass a large 18 wheeler. 
They seemingly are content riding next to many tons of metal for miles, 
forgetful of how truck drivers are known for dozing on long hauls. One 
slight error by the trucker, and they are dead!

I have watched the wave action your animation depicts in actual traffic. I
spent an hour or so in a restraunt atop a high needle, adjacent to a
clogged expressway at rush hour. I repeatedly observed the backwards drift
of the most congested traffic points, with cars pulling away from the jams
as they resumed speed, and new cars slowing in back as they meet the jam.
The jam itself (several actually), did gradually move opposite to the
motion of the traffic flow, on both sides of the highway.

Stephen Bennett
   _________________________________________________________________



Subject:      Re: Traffic Waves
From:         grohe@galaxy.nsc.com (Paul Grohe)
Date:         1998/05/29


On Sat, 23 May 1998 00:40:30 GMT,
in the newsgroup sci.electronics.design, bbeaty@microscan.com posted:

> This leads me to see that traffic waves are caused by our need to rush
> ahead whenever given the chance, and our need to pack ourselves densely
> when we meet a row of stopped cars.  Because we all behave this way,
> traffic waves form.  If we intentionally behaved differently, then
> traffic waves (and perhaps traffic jams themselves) beome impossible.

Your drivers are more "mellow" than ours `round here (SF Bay
area). 

If we let even as much as a car-and-a-half length in front of us - it 
*will* be filled. Usually abruptly, causing you to hit the brakes.

Another cause of this "backup" is anxious drivers not staying in
their lane.

I refer to this phenomenon as the "zig-zag".

When a driver sees that the lane next to them starts to move,
they then want to merge over into the "other" lane that is
starting to move. However, while positioning for a "spot" in the
other lane, they are now slowing up the lane behind them.

After a few dozen drivers do this, the lane that *was* moving
then becomes plugged with the new cars, and the lane that they
just got out of then starts to move. 

They then see the previous lane is now moving....and the cycle
repeats itself (about every mile).

This is usually most evident in the fast and next-to-fast lane.

*IF* (BIG IF) everyone would stay put and move ahead together,
traffic would flow a little smoother.

Driving a stick in stop-and-go traffic, you catch on to the
"drive slow and steady", or "buffering" method pretty quickly (so
that you don't have to work the clutch any more than you have
to).

Cheers,
Paul Grohe

---------------------------------------------------------------
 Paul Grohe                     National Semiconductor Corp.
 Associate Apps Engineer        Santa Clara, CA. USA
                   http://www.national.com	
      NORTH AMERICA     		     EUROPE  
    1 (800) 272-9959   	             +49 (0) 180-532 78 32
 mailto:support@nsc.com         mailto:europe.support@nsc.com
 Usenet Disclaimer: Any opinions expressed are mine, not NSC's
---------------------------------------------------------------
   _________________________________________________________________


Subject:      Re: Traffic Waves
From:          (William Beaty)
Date:         1998/05/29

Kevin McMurtrie (mcmurtri@wco.com) wrote:
:   There's a better way to cancel this wave then by leaving a large gap. 
: The wave is caused by overcompensation and a delayed response in each
: car.  Using a large gap is like using undercompensation and a very large
: delay to cancel the wave.  A better way is to use a negative delay to
: cancel the wave.

That's true where the traffic is oscillating.  The "Traffic Waves" I refer
to here are different: cars sitting still for awhile (more than ten
seconds), then accelerating to 60mph, only to stop again.  The next "wave" 
is often too far ahead to be visible.  You'd need to maintain a space
which is about the same length as half a traffic-wave cycle (could be
several thousand feet.)  If it was only five cars ahead, it wouldn't be
such a problem.

BTW the animation on my site is vastly simplified in order to show the
phenomena.  Real waves might have 30seconds period or more, not 1 sec.  At
that scale the cars would be 1-pixel wide! 

((((((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))))
William J. Beaty                                  SCIENCE HOBBYIST website
                                  amasci.com
EE/programmer/sci-exhibits          science projects, tesla, weird science
Seattle, WA   206                   freenrg-L taoshum-L vortex-L webhead-L


   _________________________________________________________________


Subject:      Re: Traffic Waves
From:         regnirps@aol.com (Regnirps)
Date:         1998/05/28

Remember when this whole thing was thought up, the freeway was split into
passing lanes (far left) travelling lanes and collector/distributor lanes. 
Overtaking on the right is forbidden in most states. Most of the semi vs
auto accidents in our port areas (Seattle and Tacom) happen when a car
overtakes a slower car in the traveling lanes by passing on the right in
the collector/distributor lane, finds slower traffic (naturally) and is
forcefully "overtaken" by a semi from behind that has just merged. They
don't stop so good. 

I have three rules. 
1) It is safe to be behind a big truck -- you stop much better than 
   they -- as long as you are not between two of them!
2) Try not to overtake on the right. Many people don't expect you to be
   there.
3) Yield to superior tonnage. (My grandfather's rule for maritime travel).

Charlie Springer



   _________________________________________________________________



   
Subject:      Re: Traffic Waves
From:         Paul Hovnanian 
Date:         1998/05/28

Douglas Tooley wrote:
>
> >Do you ever find yourself with an idiot behind you in this situation
> >that is hacked off that you're not right on the bumper of the car in
> >front of you and can't seem to understand that their average speed is
> >*exactly* the same whether you're on the bumper of the car in front or
> >evening out the traffic flow?
>
> I don't understand this completely, but then I don't think anyone does:
>

> I think the average speed is actually higher if you travel slower,
> rather than start & stop.  Gridlock is a rapid decrease in capacity
> from maximum as vehicle usage exceeds safe road capacity.  Gridlock is
> generally triggered by a start-stop type of event, such as at an
> accident or on-ramp (that's why we have the ramp signals).  Starting and
> stopping can be viewed as aerodynamic turbulence and each incremental
> incidence has a measurable slowing influence.

Hmm. The average speed is higher if you travel slower ...? To moify that a
little, I think you mean the carrying capacity of a road is probably
higher for steady, slow traffic than start and stop traffic. Probaby yes. 

The problem most people have with estimating flow vs. speed is that the
capacity of a road is the product of vehicle speed and the _inverse_
of inter-vehicle spacing. That is, for a given speed, the closer cars
are together, the higher the traffic flow.  Unfortunately, from an
individual's perspective, getting there at 60 mph with 500 yards ahead
seems no different than 60 mph at 50 yards (about the correct minimum
following distance). That other 450 yards could hold another 7 or 8
cars, but if I've got my space, what do I need to worry about. ;-)

Unfortunately, as speeds decrease (even if inter-vehicle space decreases
in proportion) road carrying capacity decreases. Ignore for the moment
stop and go traffic which is a symptom of traffic density overcomming
marginal drivers' ability to synchronize with the flow. If one assumes
a linear relationship between a decrease in traffic speed and spacing,
as traffic approaches zero mph, cars would occupy zero feet of roadway.
Not likely. This non-linear relationship makes road carrying capacity
increase with increased speed, because the percentage of road
occupied by vehicles diminishes with respect to the vehicle-to-vehicle
buffer space (approaching zero percent at an infinite speed 8-) ).

Other effects enhance the "efficiency" of high speeds as well. For
instance, at minimum following distances, I have a better view of
the road ahead at 60 mph than at 20 mph whan following a large truck.
This will give me a better chance to judge traffic flow, which helps
me prevent non-linear (stop and go) driving.

--
Paul Hovnanian                | spam to: Chairman Reed Hundt
hovnania@bcstec.ca.boeing.com | rhundt@fcc.gov
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man quit ^C ^c  ?Quit ?q CtrlShftDel "Hey, what does this button d..."
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Subject:      Re: Traffic Waves
From:         Michael Burr 
Date:         1998/05/27

William Beaty wrote:
>
> After driving through many stop/go traffic waves at rush hour on 520 in
> Seattle, I decided to try something.  On a day when I immediately started
> hitting these "waves", I decided to (gasp!) drive slow.  Rather than rushing
> ahead with everyone else, only to come to a halt, I decided to try to hit the
> average speed of the traffic.  I let a huge gap open up ahead of me, and
> timed things so I was arriving at the next "stop-wave" just as the last red
> brakelights were turning off.

Welcome to the club William. I've been using this approach for many
years for the following reasons.

1) Why sit on someone's bumper breathing their exhaust?
2) Leaving some space between vehicles makes traffic more fluid
3) Evening out my speed reduces risk of rear-end collision
4) Saves wear and tear on the clutch and brakes.

Do you ever find yourself with an idiot behind you in this situation
that is hacked off that you're not right on the bumper of the car in
front of you and can't seem to understand that their average speed is
*exactly* the same whether you're on the bumper of the car in front or
evening out the traffic flow?

-----------------------------------------------------------------
                           Michael N. Burr
               Renaissance Man Wanna-Be, Issaquah, WA
   _________________________________________________________________



Subject:      Re: Traffic Waves
From:         glhansen@copper.ucs.indiana.edu (Gregory Loren Hansen)
Date:         1998/05/29

In article <6km9pr$rtt$5@strato.ultra.net>,  
wrote:

>The really dangerous drivers are those who are going to teach
>everybody else a lesson in speed limits.  What they do is drive in
>the left hand lane at the speed limit or a few mph's less.  A lot
>of people hesitate passing on the right (except in this state, of
>course) so there's a backup of traffic until somebody decides to
>break the law and pass the jerk on the right (who then promptly
>blows his horn with religious fervor at the "law-breaker".

I think you meant to say that really dangerous drivers exceed the speed
limit and then pile up when they come to a law-abiding driver.

Yes, the left lane is for passing, you should do your cruising in the
right lane.  But the passing lane is not the speeding lane.  It is the "go
faster than the guy in front of you but do not exceed the speed limit"
lane.

And I, for one, think it's a pretty sorry state of affairs that anyone is
blaming accidents on the people who go the speed limit, and insist we
should all be breaking the law if we want to be safe drivers!

-- 
Stay alert!  Trust no one!  Keep your laser handy!  The Computer is
your Friend!


   _________________________________________________________________



Subject:      Re: Traffic Waves
From:         jac@ibms48.scri.fsu.edu (Jim Carr)
Date:         1998/05/29

 wrote:
}
} The really dangerous drivers are those who are going to teach
} everybody else a lesson in speed limits.  What they do is drive in
} the left hand lane at the speed limit or a few mph's less.  A lot
} of people hesitate passing on the right (except in this state, of
} course) so there's a backup of traffic until somebody decides to
} break the law and pass the jerk on the right (who then promptly
} blows his horn with religious fervor at the "law-breaker".

glhansen@copper.ucs.indiana.edu (Gregory Loren Hansen) writes:
>
>I think you meant to say that really dangerous drivers exceed the speed
>limit and then pile up when they come to a law-abiding driver.

 A driver doing what is described above is not obeying the law. 
 Even that use of the horn is a moving violation. 

>And I, for one, think it's a pretty sorry state of affairs that anyone is
>blaming accidents on the people who go the speed limit, and insist we
>should all be breaking the law if we want to be safe drivers!

 That assumes the posted speed limit is the safe and prudent speed 
 most drivers would use for the given conditions.  It is well documented 
 that drivers in the bottom decile are more dangerous to others than 
 any other group on the road, and in most cases those are people who 
 are well under the already-low posted limits. 
 
-- 
 James A. Carr        | Commercial e-mail is _NOT_ 
    http://www.scri.fsu.edu/~jac/       | desired to this or any address 
 Supercomputer Computations Res. Inst.  | that resolves to my account 
 Florida State, Tallahassee FL 32306    | for any reason at any time.

   _________________________________________________________________




Newsgroups: seattle.general
Subject: Re: Traffic Waves
Date: 30 May 1998 00:12:17 GMT
Organization: Eskimo North (206) For-Ever

Douglas Tooley (dltooley@speakeasy.org) wrote:

: I don't understand this completely, but then I don't think anyone does:

: I think the average speed is actually higher if you travel slower,
: rather than start & stop.  

Exactly.  I think of it like this: with slight waves, perhaps the traffic
goes as low as 50mph and as high as 60mph, averaging 55.  But when waves
really grow, then in parts of the wave the traffic is at 0mph, but in
other parts the drivers DO NOT speed up to 110mph to compensate.  Therefor
the stop-waves drag the average speed downwards.  Perhaps if everyone
drove at 40mph the waves wouldn't form at all, but once they do form, the
average might be 30mph or 20mph or less. 

One place I've seen this: in a floppy "whoopie cusion" noismaker.  If you
blow slowly, lots of air goes through, but if you blow just a little
faster, the thing goes FLBBTBTBTBTBTB! and the air flow drops
considerably.  You have to stop blowing for a moment in order to get rid
of the waves.

: Gridlock is a rapid decrease in capacity from maximum as vehicle usage
: exceeds safe road capacity.  Gridlock is generally triggered by a
: start-stop type of event, such as at an accident or on-ramp (that's why
: we have the ramp signals).  Starting and stopping can be viewed as
: aerodynamic turbulence and each incremental incidence has a measurable
: slowing influence.

Another reason for gridlock: if all the cars ahead of me are stopped, my
usual habit is to drive up to within a car-length of the last car and wait
there.  But when I finally see the traffic far ahead of me start to move,
I can do nothing.  I have to wait for the wave.  HOWEVER, if I had instead
decided to stop 5 car lengths from the last car in the line, then I would
not be locked in place.  If the traffic far ahead starts moving, then I
can immediately move too.  For me the "traffic wave" can travel towards me
at an enormous rate, since I can watch the traffic 20 or 50 or 100 cars
ahead, and immediately respond.  If I only have a couple of feet ahead of
me, then I can do nothing until the car ahead of me finally moves. 

If people would refuse to form "parking lots" on the highways, then they
still might drive more slowly than they'd prefer, but they never would get
into the "stuck-cannot-move" pattern.  Traffic jams and traffic waves
would then be fast-moving ripples which skip over hundreds of cars, rather
than excruciatingly slow waves which can only move through one car at a
time.

We have conscious choice.  One way to ease a traffic jam is to change our
habits and simply refuse to form a traffic jam!  Very simple, but it never
occurs to anyone to try this.  (It didn't occur to me until this year.) 
At first glance you might think that this would simply transform a
tight-packed traffic jam into a sparse-grid jam, but still nobody could
move.  Nope.  If everyone in the jam was keeping a 5-car space between
them, then when the first car in line started to move, ALL THE OTHERS
COULD MOVE TOO!  In other words, the "traffic wave" travels almost
infinitely fast, and the whole traffic jam can end abruptly, rather than
as a slow-crawling wave.

If only one person maintains a large space during a traffic jam, it won't
solve anything, right?  Wrong. Many times while in traffic-jam conditions
I have kept 5 car lengths empty ahead of me, and when I saw the brake
lights turning off in the distance, I started creeping forward.  As a
result, all the cars behind me started creeping forwards prematurely. Even
though this was only a tiny difference, it does mean that I singlehandedly
shortened the "stop wave"  by a good fraction of a minute, and also
"sucked" the leading edge of the start-wave towards me.  If only a very
few people were to do this, then traffic jams would be transformed from
total stops and into slow crawls, and the speed of traffic waves would be
vastly increased.  If a significant percentage of drivers did this, then
traffic jams could never form in the first place, they would be
transformed into moving slowdowns. 

In physics, in a glass rod, the difference between velocities of a sound
wave and a light wave is the different distances of interaction between
neighboring atoms.  For sound waves, one atom must push on its neighbor
through direct contact.  For light waves, the forces of electric repulsion
of one electron can affect all atoms over a large distance.  Light waves
travel fast because the motion of one atom can affect very distant
neighbors.  If a car in a traffic jam maintains a large space ahead of it,
that driver can notice and respond to distant changes in traffic, and
therefor change the velocity of "traffic waves" and make them fly along at
the "speed of light" rather than at the "speed of sound".

-- 
((((((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))))
William J. Beaty                                  SCIENCE HOBBYIST website
                                  amasci.com
EE/programmer/sci-exhibits          science projects, tesla, weird science





Newsgroups: seattle.general,sci.physics,sci.electronics.design
Subject: Re: Traffic Waves
Date: 30 May 1998 00:51:16 GMT

Shea F. Kenny (lunarchy@ncfweb.nut) wrote:

: 	What he's talking about is cars coming up from behind, passing
: everyone and filling up the spaces, eventually forcing people to stop.
: If they'd just stay in their place, traffic wouldn't build up or
: condense so quickly. 

In my experience, only a few drivers do this and in Seattle it is a
minority.

A much larger problem is the drivers who refuse to let anyone merge ahead
of them.  If everyone is trying to "punish" those offenders who try to
worm their way through dense traffic, then merging becomes impossible. 
But this causes traffic jams because some people MUST merge.  This
happened to me several times: 

In rush hour traffic I needed to get to my exit.  I was in the left lane,
so I signaled to merge right, but nobody would let me in.  After a long
time I found a hole and got in, but the guy behind me scowled.  The person
thought I was filling his little space out of spite or something, and he
didn't realize that I HAD TO GET OVER SOON!  OK, so now I still needed to
move over right by one more lane.  Nobody would let me in.  I started
going slower and slower as I approached my exit, and sliding into the
right lane to FORCE them to let me in.  I succeeded, and I got to my exit. 

That was last year.  Today I realize what I did: I brought two lanes of
traffic to a standstill and launched a massive "stop wave" backwards
through the chain.  If I did this, you can bet that thousands of other
drivers are doing the same.  But I thought I had justification, I didn't
have any later exits I could take.  I stopped the whole lane I was in, and
also forced the righthand lane to stop as I inched my way in and blocked
the flow.  No wonder there are traffic waves upstream from exit ramps!  I
caused the problem, but also the problem was caused by the hundreds of
drivers who wrongly assumed that I was a greedy interloper, and who
refused to let me merge.  Or perhaps they were thinking "OK, you can merge
BEHIND me". Riiiiight.  If they all think this way, then they present an
unyeilding wall. 

Today I not only maintain a huge space ahead of me, but I welcome all
comers to jump in ahead.  True, a few are idiots who think they've "won." 
But most are people who have valid reasons to change lanes.  I see that if
I try to stop or punish the idiots, then I myself will become a bigger
traffic problem then they are. 

There are a couple of places on I-5 where traffic comes in from the LEFT,
and some of those drivers need to cross and get to nearby exits at the
right.  I know about these regions because as I bring my big empty space
into them, suddenly everyone is merging right (and no doubt thanking me.) 
Obviously this sort of traffic cross-flow causes "traffic waves" and jams. 
But the cross-flow is designed into the highway, therefor the REAL cause
of the problem is that majority of people who can't stand to allow anyone
to merge ahead of them.  If everyone allowed strangers to merge ahead of
them, then quite a few sources of traffic jams would evaporate.

There's an excellent article about all this at:
   http://www.aloha.net/~dyc/ch11.html 

((((((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))))
William J. Beaty                                  SCIENCE HOBBYIST website
                                  amasci.com
EE/programmer/sci-exhibits          science projects, tesla, weird science






From: "Mark Folsom" 
Newsgroups: seattle.general,sci.physics,sci.electronics.design
Subject: Re: Traffic Waves
Date: Fri, 29 May 1998 20:57:09 -0700

William Beaty wrote in message <6knl64$9js$1@eskinews.eskimo.com>...
>Shea F. Kenny (lunarchy@ncfweb.nut) wrote:
>
>: What he's talking about is cars coming up from behind, passing
>: everyone and filling up the spaces, eventually forcing people to stop.
>: If they'd just stay in their place, traffic wouldn't build up or
>: condense so quickly.
>

I think it has a lot more to do with drivers who force lane changes at the 
last minute because they don't plan ahead or accomodate to traffic 
conditions.  Too many drivers zombie out in the left lane (where they 
don't have to deal with others merging) until they get right on top of 
their exit and then jam themselves into and through the lanes to their 
right as if it's an emergency.  Other drivers don't want to let them in 
but then jam on their brakes and stop when the lane changer forces the 
issue, stopping everyone behind them.

>In my experience, only a few drivers do this and in Seattle it is a minority.
>
>A much larger problem is the drivers who refuse to let anyone merge ahead
>of them.  If everyone is trying to "punish" those offenders who try to
>worm their way through dense traffic, then merging becomes impossible.
>But this causes traffic jams because some people MUST merge.  This
>happened to me several times:
>
>In rush hour traffic I needed to get to my exit.  I was in the left lane,
>so I signaled to merge right, but nobody would let me in.  After a long
>time I found a hole and got in, but the guy behind me scowled.  The 
person

How far ahead of the exit did you know that you had to move over?  Why did 
you put yourself in a position where it was urgent that you get to your 
exit *right away* in bumper-to-bumper traffic?

>thought I was filling his little space out of spite or something, and he
>didn't realize that I HAD TO GET OVER SOON!  OK, so now I still needed to
>move over right by one more lane.  Nobody would let me in.  I started
>going slower and slower as I approached my exit, and sliding into the
>right lane to FORCE them to let me in.  I succeeded, and I got to my exit.

Why not slide over at traffic speed?  Why not slide over sooner?

>
>That was last year.  Today I realize what I did: I brought two lanes of
>traffic to a standstill and launched a massive "stop wave" backwards
>through the chain.  If I did this, you can bet that thousands of other
>drivers are doing the same.  But I thought I had justification, I didn't
>have any later exits I could take.  I stopped the whole lane I was in, 
and

There are always later exits you can take.

>also forced the righthand lane to stop as I inched my way in and blocked
>the flow.  No wonder there are traffic waves upstream from exit ramps!  I

On the contrary, my experience in the San Francisco Bay area is that the 
right lane flows fast approaching exit ramps and then slows approaching 
entrance ramps.  However, the worst places are where the number of lanes 
decreases.  The deleted lane is usually on the right and two modes 
develop: some plan ahead and move into the continuing lanes while a few 
move to take advantage of the nearly empty right lane and move up a few 
spaces.  They race ahead and then force their way into the lane to their 
left at the last minute, causing drivers in that lane to either brake or 
move to their left, slowing all of the lanes behind them as a result.

>caused the problem, but also the problem was caused by the hundreds of
>drivers who wrongly assumed that I was a greedy interloper, and who
>refused to let me merge.  Or perhaps they were thinking "OK, you can merge

Maybe they thought you were a clueless jerk who couldn't think far enough
ahead to make timely lane changes in heavy traffic.

>BEHIND me". Riiiiight.  If they all think this way, then they present an
>unyeilding wall.
>
>Today I not only maintain a huge space ahead of me, but I welcome all
>comers to jump in ahead.  True, a few are idiots who think they've "won."

So now you're screwing all of the people stuck behind you as you go slower 
than the flow of traffic and other drivers fill in ahead of you.  What 
would be wrong with moving along with traffic and just letting people 
change lanes ahead of you when they signal to get in?

>But most are people who have valid reasons to change lanes.  I see that if
>I try to stop or punish the idiots, then I myself will become a bigger
>traffic problem then they are.
>

Sounds like you're still a pretty big problem.

>There are a couple of places on I-5 where traffic comes in from the LEFT,
>and some of those drivers need to cross and get to nearby exits at the
>right.  I know about these regions because as I bring my big empty space
>into them, suddenly everyone is merging right (and no doubt thanking me.)
>Obviously this sort of traffic cross-flow causes "traffic waves" and jams.
>But the cross-flow is designed into the highway, therefor the REAL cause
>of the problem is that majority of people who can't stand to allow anyone
>to merge ahead of them.  If everyone allowed strangers to merge ahead of
>them, then quite a few sources of traffic jams would evaporate.
>

Letting people change lanes is a good practice, but driving like a slug 
just causes exasperation and unnecessary lane changes on the part of the 
poor bastards trying to get around you.

--
Mark Folsom, P.E.
Consulting Mechanical Engineer
http://www.redshift.com/~folsom








Subject:      Re: Traffic Waves
From:         Mark Kolber 
Date:         1998/05/30


I seem to recall a math problem where we calculated that a road has the
highest capacity (most cars pass a given point per minute) at a speed of
about 25 to 35 MPH.  This assumes a 1 car length per 10 MPH gap.

Mark K






From: dltooley@speakeasy.org (Douglas Tooley)
Subject: Re: Traffic Waves
Date: Sat, 30 May 1998 10:29:26 PST
Organization: Speakeasy Cafe (FOO et al)

>One place I've seen this: in a floppy "whoopie cusion" noismaker.  If you
>blow slowly, lots of air goes through, but if you blow just a little
>faster, the thing goes FLBBTBTBTBTBTB! and the air flow drops
>considerably.  You have to stop blowing for a moment in order to get rid
>of the waves.

Love that analogy!

Highway 520 is a great place to watch this sort of thing.  For some reason 
the mid-bridge high span seems to cause slowing traffic waves, just from 
the fact that folks don't add a touch bit more gas to compensate for the 
slight climb.  Also notice how when going Westbound that traffic actually 
speeds up after the HOV lane joins the two main lanes?




From:  (William Beaty)
Newsgroups: seattle.general,sci.physics,sci.electronics.design
Subject: Re: Traffic Waves
Date: 31 May 1998 01:25:05 GMT

Mark Folsom (folsomman@redshift.com) wrote:
: How far ahead of the exit did you know that you had to move over?  

I don't know, maybe five minutes before the exit, maybe more.  Plenty of
time, if drivers in solid-packed adjacent lanes had  allowed merging.


: Why did you put yourself in a position where it was urgent that you get
: to your exit *right away* in bumper-to-bumper traffic?

Please realize that I do know that I was acting like an idiot in forcing
my way through the unyeilding wall of traffic.  I don't do that crap 
anymore.

I'm just trying to point out that this particular traffic jam was caused
by vehicles trying to merge during bumper-to-bumper traffic, and nobody
letting them in.  It's easy to accuse the merging car of not planning
ahead.  But if the "unyeilding wall" was not expected by the merging
driver, then blaming the merging driver is blaming the victim.  Sometimes
the merging vehicle SHOULD have started signalling lots earlier, and is
the cause and not the victim.  But sometimes no amount of planning
would have made a difference, because nobody was going to "lose face"
by allowing someone to merge left in front of them. 

: >thought I was filling his little space out of spite or something, and he
: >didn't realize that I HAD TO GET OVER SOON!  OK, so now I still needed to
: >move over right by one more lane.  Nobody would let me in.  I started
: >going slower and slower as I approached my exit, and sliding into the
: >right lane to FORCE them to let me in.  I succeeded, and I got to my exit.

: Why not slide over at traffic speed?  Why not slide over sooner?

I wasn't clear earlier.  I had been signalling to merge right, but the
traffic in the adjacent lane was bumper to bumper, and the whole group of
drivers in that lane was refusing to make space to let me in.  They were
refusing for a very long time.  Is this normal behavior?  I sat there for
awhile with my signal on, then slowed down a bit to try to slide along,
hoping to find an "altruist" who would allow other drivers to merge during
bumper to bumper traffic.  No luck that time. 

: >That was last year.  Today I realize what I did: I brought two lanes of
: >traffic to a standstill and launched a massive "stop wave" backwards
: >through the chain.  If I did this, you can bet that thousands of other
: >drivers are doing the same.  But I thought I had justification, I didn't
: >have any later exits I could take.  I stopped the whole lane I was in, and

: There are always later exits you can take.

Exactly!

Back then I was thinking in "asshole" mode.  So, nobody would let me in,
no matter how long I kept trying?  Well, then I'd show them!  I would
force my way in.  Does this make them all have to stop?  Well, it serves
them right!

That was then.  Now I realize that I had been stuck in "asshole-think" 
mode, coming up with self-serving justification for acting like an idiot,
while blaming others for "making" me behave that way.  Obviously I was the
ass.  But I wasn't the only one that time.  If one driver is trying to
merge, and twenty other drivers are refusing, then who is at fault?  If
the merging driver forces their way in, who then caused the resulting wave
of stopped cars?  In my opinion, everyone involved is to blame.

  http://www.aloha.net/~dyc/ch11.html  a book on Drivers' Psychology

: On the contrary, my experience in the San Francisco Bay area is that the
: right lane flows fast approaching exit ramps and then slows approaching
: entrance ramps.

Yes, another spot where merging is the issue.

: However, the worst places are where the number of lanes
: decreases.  The deleted lane is usually on the right and two modes develop:
: some plan ahead and move into the continuing lanes while a few move to take
: advantage of the nearly empty right lane and move up a few spaces.  They
: race ahead and then force their way into the lane to their left at the last
: minute, causing drivers in that lane to either brake or move to their left,
: slowing all of the lanes behind them as a result.

True.  The "greedy" drivers cause traffic to halt as they force their way
back in.  However, I think other things are going on here.  If everyone
was to ALLOW the "greedy" drivers to merge at the far end, then traffic
problems would be greatly reduced.  The problem is not just the "greedy" 
drivers who take advantage of the empty lane.  The problem arises when
the "greedy" drivers fight with the lane full of "good but judgemental" 
drivers who attempt to punish them by refusing to allow them to merge.
The "greedy" drivers force their way in, causing a traffic jam.  But if
they had been allowed in despite their transgressions, the jam would not
have formed.  Who is to blame, those who violate the unwritten rules, or
those who punish the violators?  Simple.  Both.

I suspect that sometimes there are no "greedy" drivers involved.  It's
impossible to plan ahead when you are faced with a solid-packed row of
drivers who cannot bring themselves to make a space for merging traffic
(even if the traffic is trying to merge early on, as it should).  When
three lanes change into two, if EVERYONE was to let ANYBODY merge
(specifically allowing any "offenders" to merge too), then that traffic
jam would not form.  If there are no "offenders" involved, then the
traffic jam is not caused by those who try to merge late.  It is caused by
those who wrongly attribute nefarious motives to all the merging drivers,
and would rather punish them than allow them to merge.

: >caused the problem, but also the problem was caused by the hundreds of
: >drivers who wrongly assumed that I was a greedy interloper, and who
: >refused to let me merge.  Or perhaps they were thinking "OK, you can merge

: Maybe they thought you were a clueless jerk who couldn't think far enough
: ahead to make timely lane changes in heavy traffic.

Yes.  They ASSUME that I was a clueless jerk, whether I was so or not. 
And they cannot know for sure.  In fact I actually had been trying
unsuccessfully to merge for many minutes.  I didn't turn into a jerk until
I decided to force my way into the other lane.

: >Today I not only maintain a huge space ahead of me, but I welcome all
: >comers to jump in ahead.  True, a few are idiots who think they've "won."

: So now you're screwing all of the people stuck behind you as you go slower
: than the flow of traffic and other drivers fill in ahead of you.  What would
: be wrong with moving along with traffic and just letting people change lanes
: ahead of you when they signal to get in?


Again I wasn't clear enough.  If there are no "traffic waves", then I am
not driving slow, instead I'm going at the same speed as traffic in the
adjacent lane, and the same speed as traffic forward of my gap.  Only
rarely do "greedy" people jump into the gap, so it is rare that I must
slow down to keep the gap in existence.  I suspect that this may be
different in other regions besides the Northwest.  Seattle drivers rarely
move into the gap in the adjacent lane.  One would expect the opposite,
but it doesn't happen here. 

If maintaining a gap ahead of you tends to eliminate traffic jams, but it
tends to piss off "greedy" drivers behind you who would drive crazy just
to get a few feet ahead, then which way would you yourself drive?  Would
you give into the short-term desires of those behind you?  Or might
you instead drive in a way which has long-term beneficial effects on
traffic for miles behind? 

: >But most are people who have valid reasons to change lanes.  I see that if
: >I try to stop or punish the idiots, then I myself will become a bigger
: >traffic problem then they are.

: Sounds like you're still a pretty big problem.

How so?

I agree that ordinary "greedy" drivers will perceive me in a negative
light.  After all, anyone who allows someone to merge ahead of them is
making the drivers behind them lose a tiny bit of ground.  Merging is
forbidden!   They must be punished!!  :) 

But if I see that "greedy" driving causes traffic jams, while other types
of driving can dissolve them, then why should I drive like an ass?  If I
strive to gain a tiny bit of ground, and conquer my fellow weaker drivers,
then I become the cause of traffic jams.  Driving with normal "greedy" 
behavior might satisfy the drivers behind me, who think they are getting a
bit ahead.  But what if this causes stop and go traffic to form?  What if
it causes traffic jams?  Should I think: "screw the people behind me, I
got mine!"  If I think this way, then I should not complain when the
people far ahead of me think this way too, and create traffic jams which
they might not experience, but which I do. 

Traffic jams are caused by our driving behavior, not by the rare driver
who misbehaves.  We should blame ourselves, and then alter our behavior. 
Finding someone else to blame will perhaps build up our self image, but
it won't fix the problem if the problem comes from you and I.

: Letting people change lanes is a good practice, but driving like a slug just
: causes exasperation and unnecessary lane changes on the part of the poor
: bastards trying to get around you.

If there was a type of driving behavior which "eats" traffic waves and can
dissolve traffic jams, would you want to learn that behavior?  If other
people accused you of driving like a slug, would you abandon the
technique which eases traffic jams?

((((((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))))
William J. Beaty                                  SCIENCE HOBBYIST website
                                  amasci.com
EE/programmer/sci-exhibits          science projects, tesla, weird science




From: Max Masters <789897589589drecon@ibm.net>
Subject: Re: Traffic Waves
Date: Sat, 30 May 1998 19:19:22 -0700

what the hell is wrong with you people? it only
looks like a wave when your in the car. viewed
from an overpass, you can easily see that it's
really discreet packets of mass with velocity.
the wave model breaks down due to measurement
interference and seemingly random changes in
"driver" behavior. sheesh.





From: bitbucket@wolfenet.com (Sonya)
To: bbeaty@microscan.com
Subject: Re: TRAFFIC JAM CURE
Newsgroups: seattle.general


In article <6o36e2$3ll$1@nnrp1.dejanews.com>, bbeaty@microscan.com wrote:

> Actually, all attempts at "amateur traffic engineering" must be based on
> the fact that drivers have very little effect on the traffic ahead of
> them, yet they can exert significant control on the traffic which
> follows behind.  If I were to "rubberneck" and completely halt my car
> for no reason, I could leave  a long-term traffic jam behind me.  On the
> other hand, if I approach a traffic jam at a slow speed, then a large
> gap will open up ahead of me.  The gap allows the traffic jam to trickle
> away but with no new cars piling up behind it, and when I finally
> arrive, part of the jam has been "eaten" and converted into a region of
> slower traffic behind me.  In this way a single driver can take a bite
> out of a traffic stoppage.  If the stoppage was small, then it might be
> erased entirely, and converted into a wide region of slightly slower
> traffic.  Average traffic speed does not stay the same: The stoppage was
> a nonlinear effect, and removing it causes increased overall speed.


This absolutely DOES work. In fact, I think you should buy the domain name
"www.trafficwaves.com" and I will personally volunteer to create and post
signs with the URL on every major freeway in the state.

Since reading one of the earlier posts about traffic waves, I've been
trying it out in traffic, and it's amazing. True, the hardest part is
ignoring the irritation of drivers behind you, but I just tilt up my rear
view mirror and think of something else. They seem to think that the two
feet they gain by being right on your tail will get them there faster. 

Please keep posting this now and then - it should only take a small
percentage of drivers to noticably change the traffic situation in this
state.

Sonya

Please change "bitbucket"
to "elysium" in my address
to reply by e-mail.





From  Sat Aug 15 12:29:00 1998
Date: Sat, 15 Aug 1998 12:28:02 -0700 (PDT)
From: William Beaty <>
To: Mayday0 
Subject: Re: TRAFFIC JAM CURE

On 15 Aug 1998, Mayday0 wrote:

> I visited your web site, read all of the material and I don't buy it!  I
> fully understand how your driving technique allows one driver to
> eliminate or lessen a traffic wave, however I think you missed the point
> most drivers are concerned with:  "Do I spend less time in the traffic?" 

A good point!  I'll have to add this to the FAQ.

Sometimes the time spent in traffic will be unaffected by the removal of
jams or waves.  Then the effects are a matter of personal opinion: would
you rather drive for 20 minutes at high speed, only to be stuck in a 0-mph
traffic jam for 20 minutes?  OR would you rather drive at half the speed
for 40 minutes?  I absolutely HATE sitting still, stuck in traffic.  I
would always choose the half-speed, no-stoppage option. 

As for waves, I've heard that stop-and-go driving is a major cause of
fender bender collisions.  If people LIKE traffic waves, and see no need
to smooth them out, then they should not complain if a sudden-braking
situation gets them rear-ended.  Don't blame the guy who hit you, blame
the traffic-waves for creating a dangerous situation.
 
> Nice orderly traffic means nothing if it takes longer to get where you
> are going!  You may think that it is obvious that it has to reduce the
> time everyone spends in traffic but I don't buy it without some sort of
> mathematical proof.  There must be some point where too many people
> leaving too large of gaps just slows everyone down.  How do you know
> that your technique reduces the time people spend in traffic? 

I do not.  After messing with these techniques, I have the distinct
impression that often they speed up traffic, sometimes they have no
effect, and less often they slow things down.  If I was sure that they
were slowing things down most of the time, I would stop doing them.

If ALL drivers in a traffic jam were to maintain HUGE spaces, then that
might create problems.  But this is no reason to argue against a FEW
drivers doing this.  Or, if one in five drivers were to practice these
driving techniques, then they might only need to maintain 2-3 carlengths
rather than 10 carlenghts or more. 

My main argument is by analogy with water turbulence in a tube.  If we
pump water through a tube, and increase the flow rate, the flow will
suddenly turn from "laminar" to "turbulent".  At the time that this
occurs, the flow rate goes down.  But if greater pressure is then applied,
then the flow rate remains turbulent but it increases.  If there were a
way to maintain the non-turbulent or "laminar" flow under high-flow
conditions, more water could be pumped through the tube per second. 

Adding detergent to water can affect the buildup of turbulence and aid the 
flow rate.  Special coatings on the tube's inner surface will also do 
this. Dolphins have a weird skin texture, and if artificial dolphin skin 
is put on a speedboat, it prevents the creation of the microscopic "waves" 
which lead to massive turbulence, and so allows the boat to go faster 
without installing a larger engine.  If we could somehow design 
"intelligent water" which would see the tiny waves of turbulence and 
somehow quash them, then that water would pour through a pipe faster.  
Smart drivers in heavy traffic are like "intelligent"  molecules of water.

But is fluid turbulence an appropriate analogy?  Obviously it cannot be a
perfect analogy.  Obviously there will be traffic conditions where fluid
turbulence is not an analogy at all.  I suspect that the fluid analogy
applys well enough, and often enough, that "traffic wave" driving
techniques are very worthwhile.  It would take an actual scientific study
before I could PROVE that this was the case.  If you insist that, since
proof is lacking, we should do nothing, then that is your opinion.  My
opinion is that the safety benefits and psychological benefits alone make
these driving techniques worthwhile, even if they did turn out to have
little effect on the time we all spend in traffic jams.


((((((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))))
William J. Beaty                                  SCIENCE HOBBYIST website
                                  amasci.com
EE/programmer/sci-exhibits          science projects, tesla, weird science
Seattle, WA   206-          freenrg-L taoshum-L vortex-L webhead-L







From  Tue Aug 18 12:52:50 1998
Date: Tue, 18 Aug 1998 12:50:40 -0700 (PDT)
From: William Beaty <>
To: "M. Swell" 
Subject: Re: hmmm

On Tue, 18 Aug 1998, M. Swell wrote:

> Why is it going southbound on I-5, right before the 520 exit, that 
> traffic is backed up going uphill, and right after the uphill part, a 
> driver can go 70-75 easily? And not during rush hour, in general as 
> well...

I drive that section too (and get to practice jam-cancelling techniques
there).

I'm convinced that this clot is caused by all the people trying to merge
left to get to 520 exit.  It's a runaway process:  those who need to merge
will start slowing down.  Slow drivers pack themselves together.  This
prevents merging, which makes merging drivers go even slower, which packs
cars even closer, etc.  During rush hour this causes a jam.  At other
times it causes a mysterious slowdown. 

Lots of traffic comes in from the right at 50th and 45th entrance ramps,
which creates "merging lane" jams in the rightmost lane.  Also, many of
those drivers are merging across to the 520 exit.  Also, lots of drivers
who are already on the right half of the highway need to exit at 520.  All
of these cars have to cross all those lanes quickly, before they pass the
520 exit.  THerefor they drive slow and look for holes.  But slow driving
tends to close the holes! Some drivers who are already in the left lane
are there for thru-traffic reasons.  When the crowd of 520 users comes
pouring in, the people already in the left lane try to merge right. 
Competition ensues, which ruins any opportunities for merging.  (Merging
thrives on cooperation.)

There's no easy way to stop people from merging left across many lanes of
traffic.  However, I find that if I bring a 20-car-length space into that
jam, all sorts of happy people instantly merge left into it.  They are the
ones who need desparately to get over to 520, but are blocked by tightly-
packed cars.  It's really fascinating to watch.  Of course I have to start
early at the Northgate or 80th entrance, otherwise I wouldn't have time to
build up a big pulse of "antitraffic".

Conclusion: if people knew to maintain spaces and allow merging, then I
predict that the particular slowdown on south I-5 at the Ship Canal
bridge at would be vastly reduced.

((((((((((((((((((((( ( (  (   (    (O)    )   )  ) ) )))))))))))))))))))))
William J. Beaty                                  SCIENCE HOBBYIST website
                                  amasci.com
EE/programmer/sci-exhibits          science projects, tesla, weird science
Seattle, WA   206-          freenrg-L taoshum-L vortex-L webhead-L