Traffic Zoology

http://bikereader.com/BikeReader/con...g/zoology.html

"Sam" wrote in message
m...

http://bikereader.com/BikeReader/con...g/zoology.html

That is absolutely perfect! They have analysed and documented the "cage
train" effect!

--
Guy
===

WARNING: may contain traces of irony. Contents may settle after posting.
http://www.chapmancentral.co.uk

On Mon, 9 Feb 2004, Just zis Guy, you know? wrote:
"Sam" wrote in message
m...

http://bikereader.com/BikeReader/con...g/zoology.html

That is absolutely perfect! They have analysed and documented the "cage
train" effect!

On the topic of crossing traffic with science, I saw something once
comparing traffic behaviour on motorways to that of compressible fluid
dynamics. In particular, the existence of propogating and standing
shock-waves and nozzles (ie, at supersonic speeds you decelerate a
flow with what you'd think was a nozzle, just like motorways - put in
a constriction and the speed drops).

Has anyone else ever come across this?

regards, Ian SMith
--
|\ /| no .sig
|o o|
|/ \|

Ian Smith wrote:
On Mon, 9 Feb 2004, Just zis Guy, you know? wrote:

"Sam" wrote in message
m...


http://bikereader.com/BikeReader/con...g/zoology.html


That is absolutely perfect! They have analysed and documented the "cage
train" effect!


On the topic of crossing traffic with science, I saw something once
comparing traffic behaviour on motorways to that of compressible fluid
dynamics. In particular, the existence of propogating and standing
shock-waves and nozzles (ie, at supersonic speeds you decelerate a
flow with what you'd think was a nozzle, just like motorways - put in
a constriction and the speed drops).

Has anyone else ever come across this?

Wasn't there a Horizon program about this?

Modelling traffic flows, and illustrating the knock-on effects of lapses
of concentration causing heavy braking which builds into shockwaves of
heavier braking until there's a stoppage which propagates backwards.

This is why lower speed limits help crowded roads.

"Ian Smith" wrote in message
...
On Mon, 9 Feb 2004, Just zis Guy, you know?
wrote:
"Sam" wrote in message
m...

On the topic of crossing traffic with science, I saw something once
comparing traffic behaviour on motorways to that of compressible fluid
dynamics. In particular, the existence of propogating and standing
shock-waves and nozzles (ie, at supersonic speeds you decelerate a
flow with what you'd think was a nozzle, just like motorways - put in
a constriction and the speed drops).
Has anyone else ever come across this?


Remember an article in "Scientific American" many years ago, likening traffic
flow to what happens in a travelling wave tube where electrons bunch together
causing amplification or oscillation effects. It was followed later by a
Horizon programme picking up on the same paper.

--
M Stewart
Milton Keynes, UK
www.megalith.freeserve.co.uk/oddimage.htm
http://myweb.tiscali.co.uk/ms1938/

On Mon, 9 Feb 2004 19:44:45 +0000 (UTC), Ian Smith
wrote in message
:

On the topic of crossing traffic with science, I saw something once
comparing traffic behaviour on motorways to that of compressible fluid
dynamics. In particular, the existence of propogating and standing
shock-waves and nozzles (ie, at supersonic speeds you decelerate a
flow with what you'd think was a nozzle, just like motorways - put in
a constriction and the speed drops).

Congested motorways are often given as a good example of turbulent
flow. I don't have asource which discusses it, but I'm sure they use
fluid dynamics to model traffic flow.

Guy
===
May contain traces of irony. Contents liable to settle after posting.
http://chapmancentral.demon.co.uk

Mon, 9 Feb 2004 19:44:45 +0000 (UTC),
, Ian Smith
wrote:

On the topic of crossing traffic with science, I saw something once
comparing traffic behaviour on motorways to that of compressible fluid
dynamics. In particular, the existence of propogating and standing
shock-waves and nozzles (ie, at supersonic speeds you decelerate a
flow with what you'd think was a nozzle, just like motorways - put in
a constriction and the speed drops).

Has anyone else ever come across this?

http://www.theatlantic.com/issues/2000/12/budiansky.htm

This one discusses an article that compares traffic to gas molecules.
--
zk

Has anyone else ever come across this?

You mean all those tail backs that appear for no reason? Yeah - we all have!
grrrr


---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.580 / Virus Database: 367 - Release Date: 07/02/2004

In article , ExGuardianReader
writes
Ian Smith wrote:
On Mon, 9 Feb 2004, Just zis Guy, you know?
wrote:
"Sam" wrote in message
m...


http://bikereader.com/BikeReader/con...g/zoology.html

That is absolutely perfect! They have analysed and documented the "cage
train" effect!

snip

Has anyone else ever come across this?

Wasn't there a Horizon program about this?

Modelling traffic flows, and illustrating the knock-on effects of lapses
of concentration causing heavy braking which builds into shockwaves of
heavier braking until there's a stoppage which propagates backwards.

This is why lower speed limits help crowded roads.

I thought it was driving too close (and over-braking) that caused the
compression wave of traffic but I may be wrong. I remember from Horizon
that the optimum speed for traffic throughput was 18mph, mainly due to
how close you can pack the cars. Always thought that was low, but there
you go...


--
John Openshaw

On Mon, 9 Feb 2004 20:41:27 +0000 (UTC), ExGuardianReader wrote:
Ian Smith wrote:
On Mon, 9 Feb 2004, Just zis Guy, you know? wrote:

"Sam" wrote in message
m...


http://bikereader.com/BikeReader/con...g/zoology.html


That is absolutely perfect! They have analysed and documented the "cage
train" effect!


On the topic of crossing traffic with science, I saw something once
comparing traffic behaviour on motorways to that of compressible fluid
dynamics. In particular, the existence of propogating and standing
shock-waves and nozzles (ie, at supersonic speeds you decelerate a
flow with what you'd think was a nozzle, just like motorways - put in
a constriction and the speed drops).

Has anyone else ever come across this?

Wasn't there a Horizon program about this?


There was a New Scientist article a few years ago.

--
Trevor Barton