gjphw@ihuxm.UUCP (06/15/83)
This note is in response to a query by W. Montgomery about the behavior
of traffic during rush hours. The original article was posted on 13 Jun 1983.
A very well written book titled "Linear and Nonlinear Waves" by Whitham
contains, among others, a nice treatment of highway traffic during heavy traffic
periods. Engineers can use these techniques quite successfully to study and
predict traffic behavior when they design new higways. The traffic is simply
considered to be a fluid and most of the laws of fluid motion can be applied.
The areas where the traffic flow seems to slow then speed up again are
density waves that propagate through the traffic fluid. The speed on the
highway is determined by the separation between automobiles (molecules) and
the reaction time of drivers. This density wave may have been established
by some simple disturbance along the highway, or even by the traffic slowing
down while traveling up a hill (increased resistance). The wave then travels
on its own. In very heavy traffic, the wave can propagate backward through
the traffic flow at up to 20 miles per hour. This wave eventually dies out
due to the imperfections in drivers' responses (dispersion).
The book is generally a good introduction to wave phenomena in media.
It also appears that automobile drivers practice only short range interactions,
and that all of those intelligent people become indistinguishable from a
collection of insensate molecules when they are behind a wheel. Perhaps crowd
behavior is incapable of displaying any long range interactions.
Patrick Wyant
*!ihuxm!gjphw
Bell Labs (Naperville, IL)jdj55611@ihuxk.UUCP (06/16/83)
As far as trying to even out the flow of traffic in crowded situations, I have tried to be an elastic molecule and maintain a constant speed. My findings are that I am worse off because of all the insensate molecules in the other lanes that spot the small opening in front of me and cut in causing me to brake more readily than before. Again, the statement that the few molecules that know about fluid flow are overwhelmed by the rest. J. D. Jensen BTL Naperville Il.