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From: dje@5941ux.UUCP
Newsgroups: net.physics,net.auto
Subject: Re: physical laws of freeway traffic?
Message-ID: <284@5941ux.UUCP>
Date: Mon, 13-Jun-83 12:29:40 EDT
Article-I.D.: 5941ux.284
Posted: Mon Jun 13 12:29:40 1983
Date-Received: Wed, 15-Jun-83 03:14:38 EDT
Lines: 17

Having to commute up and down NJ Route 287 every day during rush hour, I too
wonder about the reasons for stop-and-go traffic.  One possible reason is that
a car will not always match the speed of the one in front of it.  If one 
vehicle is traveling at 40 mph and the one behind it slows to 30 mph, then all 
cars following in that lane have to slow to 30 mph (or else pack that much 
tighter, which also slows things down).  If traffic is sufficiently heavy, this
kind of chain reaction may continue until one driver approaching the car in 
front has to stop before hitting it.  It is similar with cars changing lanes:  
when a car enters a lane, the car behind it has to crowd in closer or slow down
to make room. 

If mathematical solutions are hard to come by, a simulation model might also
be helpful in providing insight into the process.

Dave Ellis / Bell Labs, Piscataway NJ
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