[Tagging] works_as_highway=primary

moltonel 3x Combo moltonel at gmail.com
Tue Jul 28 14:14:22 UTC 2015

On 28/07/2015, Martin Koppenhoefer <dieterdreist at gmail.com> wrote:
>> Am 28.07.2015 um 11:02 schrieb Pavel ZbytovskĂ˝ <zbytovsky at gmail.com>:
>> 1) technically the small secondary roads part works as primary road
>> network. So we would suggest a tag similar to works_as_highway=primary. Do
>> you think its ok? Any suggestions?
> from what you have written it seems to me that these are tagging errors: if
> a road "works as primary" it should get the primary tag in osm.
> Country specific deviations that result from following different criteria
> (like road maintenance class / entity, or physical criteria, etc.) should be
> "repaired" (map those properties differently and not in the highway tag) and
> the highway tag should be used like it is elsewhere.

Sorry but no, too simplistic. A lot of local OSM communities follow
the official national road classification where possible. For example
in Ireland, any ref=Nxx road with xx<51 is highway=trunk, and switches
to highway=primary when xx>50.


This makes sense because it is expected by any Irish driver and map
user. While it does result in some road classification changes without
any physical changes, this just reflects the administrative reality.

> OSM is a global dataset and following everywhere the same criteria to
> determine the highway tag is important for a smooth usage of the data across
> borders.

That ideal doesn't match the practical reality. highway=primary has a
very different definition between Ethiopia and Germany, by necessity.
A global uniform standard for highway=* would be pretty unusable. But
we do use a collection of local standards, so we have local
consistency (hopefully at least at the national level), which is the
most important thing.

That said, there are plenty of tags other than highway that are
usefull and objective: maxspeed, lanes, width, traffic lights, speed
bunps, and even surface (but that one is getting subjective again). Go
map them, in that rough order of priority. They are used by routing
software and solve the OP's question for routing. If you want to use
those tags for rendering, talk to your map style developer (you'd need
to do that anyway to make use of works_as_primary).

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