[OSM-talk] zones for motorway/in town/outof town?

Guenther Meyer d.s.e at sordidmusic.com
Thu May 21 16:39:00 BST 2009


Am Thursday 21 May 2009 schrieb Radomir Cernoch:
> Ok, then why should we have the polygons?
>
we are talking here about the mentioned tags for the traffic, not 
administrative or other boundaries, right?
ok,. let's see:

> * It models the law more accurately.
false. the traffic laws apply to streets only, not to buildings, areas, other 
polygons, footways, ... which are also inside the given polygon.

> * Therefore you can infer more information.
> * You can refine the details of the map gradually over time. At the same
>   it allows a truthful interpretation of the OSM data all the time.
> * If someone forgets to add the "maxspeed" or "zone:traffic" tag to a
>   road, this model is closer to reality. (Please note that this may
>   happen in a very well made map, see my previous "Helsinki" mail).
how about roads crossing the polygon but that aren't part of the zone?
if there are things not tagged, then the result is NOT closer to reality.

> * Therefore it's friendlier to newbies.
>
I don't think so. not for traffic specific tagging.

> The most serious flaw so far:
>
> * The question of querying "node" within a polygon or "line" withing a
>   polygon. So far it seems that such query is doable using PostGis.
>   Nevertheless this needs to be confirmed.
>
postgis or other similar software.
a lot of overhead that could be avoided. not good for developing software 
running on small devices with limited resources.
a very complex for developers who can't rely on gis systems.


> > instead of using a complicated polygon-struction (which is btw not as
> > correct as just giving the road a tag) you simple can give any oficial
> > roads (e.g. no tracks oder private service-ways) of the town a
> > trafficzone=in_city and giving the zone-30-roads a maxspeed=30. Finished
> > ;)
> >
I woud go the same...

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