Re: Suggested Route Method

On Oct 14, 1:21 am, Mike Williams <nos...@econym.demon.co.uk> wrote:
> Wasn't it alan tarn who wrote:
>
>
>
> >ohh .thanks for this important information . however . do u have any
> >idea on how to go about doing this "suggested route" thing? Thanks .
>
> Your only legal strategies are:
>
> 1) Throw the request at maps.google.com, and let it do the suggestions,
> i.e. open a new browser window and pass it something likehttp://www.google.com/maps?f=d&source=s_d&saddr=Jurong+West,+Singapor...
> ddr=Ang+Mo+Kio,+Singapore&hl=en
>
> 2) Just display the normal route and the avoid highways route.
>
> 3) Try to guess sensible waypoints to add in the middle of he route that
> might lead to reasonable alternatives. That's not easy unless you have a
> database of highways or highway intersections, and can look for such an
> intersection that's somewhere between your start and end points (for
> some approximate value of "between").
>
> There may be problems using lat/lng coordinates for the waypoints,
> particularly if there's a dual carriageway involved. If the coordinates
> are for a point on the wrong carriageway, GDirections will drive a
> considerable distance out of your way so that you visit the wrong side
> of the road. But even using street names you may well get strange kinks
> near the waypoints, like this:
>
> from: Jurong West, Singapore to: Ayer Rajah Expy singapore to: Ang Mo
> Kio, Singapore

Interesting:
http://www.geocodezip.com/example_geo2.asp?waypts=yes&addr1=Jurong+West,+Singapore&addr2=Ang+Mo+Kio,+Singapore&waypt=Ayer+Rajah+Expy+singapore&geocode=1&geocode=2

-- Larry

>
> Perhaps the only way to really deal with that is to include points on
> both sides of a dual carriageway, and well clear of roads that cross
> underneath or overhead, and then try to filter out the ones that are
> silly.
>
> Consider these examples
>
> from: Jurong West, Singapore to: 1.32558,103.740764 to: Ang Mo Kio,
> Singapore
>
> from: Jurong West, Singapore to: 1.32582,103.740764 to: Ang Mo Kio,
> Singapore
>
> One of those adds 7 minutes to the trip by a complicated excursion to
> visit the wrong side of the road.
>
> Writing code to filter out silly routes isn't easy. As a first
> approximation, you could discard routes that have estimated times that
> are more than, say, 10% longer than the initial route. And you can also
> compare the durations for pairs of points on opposite sides of a dual
> carriageway and always discard the slower one.
>
> Writing code to discard duplicate routes isn't easy either. For example,
> a point on Bukit Timah Expy or Kranji Expy might create a route that's a
> duplicate of Google's Seletar Expy suggestion.
>
> --
> Mike Williamshttp://econym.org.uk/gmap
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