
Google Maps Now Suggests Alternate Routes - vaksel
http://www.techcrunch.com/2009/05/22/google-maps-now-suggests-alternate-routes/
======
RiderOfGiraffes
I've just tried this. Weird choices. Main route was about 200 miles, 3 hours
50. Alternates were significantly longer in both distance and time. By hand
with one point I got a route that was 180 miles and only 3 minutes longer.

I know about the TSP, complexity theory, and the difficulties in doing this
sort of thing, but I admit to being confused as to the choice of alternatives.
I'd be interested to know something of the criteria being used.

~~~
cperciva
I think techcrunch is misunderstanding the purpose of alternate routes -- the
point is to allow people to say "hmm, the radio traffic report says there's an
accident on bridge X... what good routes are there which avoid that bridge?"

As such, it's not useful to provide "the best N routes" -- instead, the point
is to find N good routes which do not overlap more than necessary. In your
case, Google probably decided that the best route was 200 miles and 3h50m, and
then ignored the route you found because it was "too similar" to the route it
had already found.

