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

[Radomir Cernoch]

Cartinus píše v Čt 21. 05. 2009 v 01:01 +0200:
> It is completely possible for a village ringroad on a bridge (highway=primary 
> or secondary) to have a maxspeed of 80 km/h due to being outside the build-up 
> zone, not because there is a sign on it that says 80 km/h. It is also 
> possible at the same time for the road under that bridge to have a maxspeed 
> of 50 km/h due to being inside the build-up zone. The point of the bridge has 
> one lat/lon, but the roads are vertically separated. This will never fit in 
> any 2D model.

I do not think I am missing the point. Your situation would be handled
like this:

1) There is 1 polygon with a tag "zone-50".
2) The road under the bridge has only 1 tag "highway=residental".
3) The ringroad over the "zone-50" has 2 tags:
   "highway=primary" and "maxspeed=80".

[There is _no_ polygon with "zone-80"!]

If you ask for the limit on residental road, the answer is:
"50", because it lies within the "zone-50" region.

If you ask for the limit on the ringroad, the answer is:
"80", because it has the tag "maxspeed=80", which has greater importance
than the "zone-50".

If you ask for the limit of the lat/lon, where the roads have
intersection on the map, the answer is:
"Ambiguous. You must specify the road, you are asking for!"

Did I explain it clearly this time?

Yours,
Radek Černoch