[Routing] Bad routing: U turns for highway links?

[Apollinaris Schoell]

On Fri, Jul 16, 2010 at 2:21 PM, Alan Millar <am12 at bolis.com> wrote:

> Hi-  I'm a user, not developer, trying to clean up the data in my area to
> make it more usable for routing and directions.
>
> Several times now I have come across a situation that seems wrong, and has
> not improved by itself in the last year or two as far as I can tell.  That
> is where routers want you to make a U-turn on a highway link.
>
> My most recent example is here:
>
>
> http://maps.cloudmade.com/?lat=45.418666&lng=-122.321563&zoom=16&directions=45.41881686582581,-122.32349395751953,45.4324308667588,-122.36778259277344&travel=car&styleId=1
>
>
to make it absolutely correct you will need a no-left turn restriction but
this looks like a wrong cost function for the router. It's not exactly a
U-turn just a very bad angle to turn onto the trunk in this direction.
 Garmin has a very high cost for such turns because they require to slow
down dramatically and default algorithm is fastest. Here it's a clear sign
for a bad router algorithm or cloudmade has an incomplete data. I still get
wrong tiles in some zoom levels. So maybe the correct ramp is not yet seen
for routing.




>
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