[Tagging] Zones and defaults [fork from: access in the wiki]

Martin Koppenhoefer dieterdreist at gmail.com
Fri Dec 5 10:54:25 UTC 2014

2014-12-04 17:57 GMT+01:00 althio forum <althio.forum at gmail.com>:

> Martin Koppenhoefer <dieterdreist at gmail.com> wrote:
> > there is actually a proposal for this kind of zone, to be mapped as a
> > polygon, useful e.g. for rendering (with name, ref, etc.), but probably
> not
> > very transparent to inherit access-tags to ways from this.
> >
> http://wiki.openstreetmap.org/wiki/Proposed_features/boundary%3Dlimited_traffic_zone
> This is not what I am proposing. My tags are for streets highway=*;
> not for a polygon. With direct tags and no need for inheritance from
> polygon to ways.

Neither am I proposing inheritance (too complex, not very transparent). I
meant to say that this tag is intended to map the actual zone (its name,
its ref, its area and boundary, its operator, etc.). No need to have this
on the individual highways, it is sufficient to have the actual (typically
time-dependent) restrictions on the highways.

> Go beyond my summary and see explanations in my post instead:
> >> So possible tag for a ZTL in Italy could be:
> >> highway=IT:limited_traffic_zone (scheme similar to
> highway=living_street)
> >> OR
> >> highway=residential/pedestrian + zone:traffic=IT:limited_traffic_zone
> >> (scheme similar to zone:maxspeed=FR:30 or zone:traffic=DE:urban)
> As you mentioned these schemes zone:*=[country]:* follow practical
> tagging on each street not "zones".

no, these zones are nothing country-specific, they are city-specific.
This is really another thing than a 30-zone in Germany for instance.

> It is not the primary tag, just an additional tag "+ zone:*=*"  and
> merely indicates that a particular way belongs to a real-world zone.

There is no use (IMHO) in adding these duplicates to individual ways, you
can see from the boundary that there is this specific limited traffic zone.

> Several road classes (from motorway to residential and special road
> types like pedestrian, living_street...) could benefit from sensible
> defaults. AFAIK some road classes do already imply defaults.

"defaults" are something for that data consumers need when actual data is
missing. ;-)

> Furthermore these defaults can be country-specific. Access
> restrictions could similarly be included as defaults in a road class.

there are wikipages that try to define these defaults, and there are common
assumptions for specific road classes (e.g. motorway, pedestrian), also
country specific ones. IMHO this should not be used to remove tags that are
defined as "default". In a system like OSM you always have the problem that
the absence of a tag can mean 2 things: incomplete data/mapping or default
data. Until you add the tag you won't know. Please search the archive, this
was discussed several times in depth.

> / RANT /
> Geez... Martin, it would be better if you reply to the full-extent
> discussions and not to the short statements from a summary.

I'm trying to keep this readable and to discuss the essence or details that
I'm interested in. If the individual contribution gets too long on a ML,
people will not read it at all...

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