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Re: 30 Years-No Speed Improvement



In article <...> jor@iis06.IAS.berkeley.edu (Jason O'Rourke) writes:
 > Michael Adams <msadams@netcom.com> wrote:
 >>Can anyone think of a technical field that has not improved its efficiency
 >>in 30 years?  The only one I can think of is our highway system.  It is
 > 
 > Hard to say if even that is true.  Hell of a lot more cars in California 
 > now.

This is, in fact, an interesting point.  Part of the problem is in what
measure of "efficiency" one is interested in.  I would imagine that the
Michael Adams prefers to measure the transportation efficiency in terms
of the amount of time it takes for one completed trip.  I would imagine
that traffic engineers concentrate more on throughput, ie, the number of
vehicles carried per unit time.  Although these two measures can be
correlated, they are not necessarily so.

For example, if it were possible to double the number of cars carried
past a single point on the freeway by reducing the average travel speed
from 60 to 40mph, then you would be able to increase throughput while
also increasing average trip length.  By one measure this would be a
loss of "efficiency", but by the other it would be a gain.

Disclaimer:  I am not suggesting that such a scenario is reasonable from
a physics or traffic engineering point of view, I am just inventing a
scenario to illustrate that overall system efficiency and individual
efficiency are not necessarily the same.


--
Thomas A. Russ,  USC/Information Sciences Institute          tar@isi.edu    


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