An interesting problem: distance estimating

[John Chambers]

| > On Thu, Jan 03, 2008 at 10:16:09AM -0500, markw at mohawksoft.com wrote:
| >
| > So adjust to suit your intuition:
| >
| > - for x > 250 miles, return x
| > - for 100 < x < 250 miles, return 1.05 * x
| > - for 10 < x < 100 miles, return 1.1 * x
| > - for x < 10 miles, return 1.3 * x
|
| That just seems too arbitrary, there should be some curve I could use :-)

Unfortunately, travel times aren't even a continuous function of  the
route and distance.  I found a good example of this a couple of years
ago, when I had to travel once or twice a week from home  in  Waltham
to an event in Taunton.  After a few trips, I noticed that my arrival
time was either before 5:30 or after 7 (pm). I couldn't arrive at any
time  between  those.  If I left too late, slightly after 4:30, I was
driving into the growing rush-hour(s) traffic, and the  arrival  time
jumped from 5:30 to 7 no matter what time I left.

Travel routes that pass near metro areas tend to have discontinuities
like  this,  due to the wildly changing speed limits (enforced by the
traffic rather than the police) over most roads during certain  parts
of the day.

OTOH, if you can avoid metro areas (including most small  ones),  you
might be able to find a rough heuristic.


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