[OSM-talk] Highways tagging vs Polygon

Radomír Černoch radomir.cernoch at gmail.com
Sat May 23 14:24:57 BST 2009


Hi,

the whole idea of polygons is over anyway... So my only answer to your
points is "yes". :-)

Radek

2009/5/23 Lauri Kytömaa <lkytomaa at cc.hut.fi>:
> Radomir Cernoch wrote:
>>> http://openstreetmap.org/?lat=60.18933&lon=24.9642&zoom=18
>>I do not
>>think that streets like Sturenkatu or Teollisuuskatu, nor any of
>>connected primary/secondary/tertiary form a "zone". I would suggest to
>>define a "zone" as an "area with predominantly uniform traffic
>>regulations".
>
> Not that it matters in Finland, but urban roads are more often signposted
> as "zone 30" or "zone 40" and not "maxspeed 30/40", at least in Helsinki.
> Such zones can't be made up at will, but can only be surveyed by entering
> an area from all directions. To me the maxspeed is just a property of the
> road, even if the authorities have signed them as a maxspeed zone.
>
> Likewise the urban area (as defining the applying traffic rules, mainly
> maxspeed=50/80) can't be accurately deduced from landuse areas,
> residential roads nor from any administrative boundaries yet entered. The
> only relevant legislative differences are the maxspeed and whether honking
> is allowed to signal starting an overtake, but no one does that anyway.
>
> Examples:
> in http://openstreetmap.org/?lat=60.221&lon=25.035&zoom=16
> everything is urban, but
> in http://openstreetmap.org/?lat=60.193&lon=25.03&zoom=16
> only the trunk road is not urban (as are all trunk roads inside Helsinki)
>
>>* 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).
>
> Actually, if there was a polygon with zone:traffic, it'd likely be wrong.
> Those roads most likely have a maxspeed of 30 or 40 and without a proper
> survey(*1) they would still be inside a zone:traffic=urban, which would
> imply a maxspeed 50 in Finland. Guessing a zone from the other minor
> roads, roads that aren't connected to those without a maxspeed
> (Allotriankuja and Rialtonkuja in the example), would indicate a maxspeed
> zone of 30 or 40 - a 50 percent probability of being wrong. Without a
> given maxspeed it's known to contain incomplete information.
>
> *1 Someone unkown drew most of the roads in Helsinki in 2007 from the
> Yahoo aerials and there's still much to add details to. A chance to get
> the house numbers, too. It's a work in progress, even if it looks quite
> detailed in places.
>
> With about 600 mappers (ever having edited anything) in Finland and 300
> 000 km of roads it's going to take a whole lot of time, esp. outside the
> significant cities.
>
> --
> Alv
>
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-- 
Radomir Cernoch
+44 750 708 8293 / +420 607 282 031
Email, Jabber: radomir.cernoch at gmail.com




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