Re: [Phys-l] Historical trivium

[brian whatcott <betwys1@sbcglobal.net>]

On 11/21/2010 6:00 PM, Philip Keller wrote:
> But LOCAL density values are not all that matters.  What makes NJ special is that the density values extend over a great area.  If your town has a density of 5000 people per square mile, but everyone lives in town and the surrounding areal has density orders of magnitude lower, no one has to drive that much!  Here in NJ, it seems that everyone lives here and works there...
Yes I see that. So its not the population density that is crucial, but 
the traffic density on the average trip.
It is said that the average car is driven 12000 miles a year.  That 
represents 1000/month or 33 miles/day on average.    The great majority 
of drivers will end up where they started, so the average trip would 
extend at most 17 miles on the average day. If two trips were 
considered, they would each stretch eight or nine miles.  Locations 
where traffic flows in different directions would be natural hazards, no 
doubt.
Traffic lights work pretty well (I think).   4 way stops less well and 
unmarked busy intersections yet less well.  But I am guessing.
Accident statistics for each intersection type at specified traffic flow 
rates would provide more objective evidence than the sort of "My Dad can 
beat your Dad" type of assertions I am seeing here.

Brian W