[Talk-ko] Highway classification and tagging

[Gabor Tanz]

Hello,

While editing roads and finding some odd classifications i found the
following guide in the wiki
https://wiki.openstreetmap.org/wiki/Korea_Road_Classification. However as
indicated by the header this seems to be a draft. Though it largely matches
what is written on the korean map features page (
https://wiki.openstreetmap.org/wiki/Ko:Map_Features), but this might not be
up to date.
I want therefore discuss what can be improved here to make it consistent
and have the documentation up to date so other mappers won't tag the roads
"wrong".

The following classification are in my opinion fine and don't need change:
- National Expressways (blue and red shield with number) ->
highway=motorway
- Local Routes (yellow rectangle with number) -> highway=secondary
- Other roads with painted centerline but no number -> highway=tertiary

The following are unclear:
- National Routes (blue oval with number), in the english wiki it is
suggested to tag with highway=trunk, in the korean with either trunk or
primary.
If we use trunk as an importance classification then all National routes
would be trunk since they are of national importance (as opposed to local
like Metro Expressways/Routes). The classification in this case doesn't say
anything about the performance, but this can be expressed with other tags.
For example:
- lanes=* for the width/throughput
- motorroad=yes if it is motorway-like, meaning physially divided/dual
carriageway, grade-separated intersections. I've also seen expressway=yes
in other countries, though it isn't used in Korea (0 vs 3202 uses according
to https://taginfo.osm.kr)
- maxspeed=* for the speed limit
- separate ways if it divided/dual carriageway
However I've also read the argument that a road with many intersections or
stoplights shouldn't be a trunk road. In my opinion that would be mixing
importance and performance for the meaning of trunk. If I was driving
through the country and not using expressways, then the most
straightforward route will probably be using National Routes. Should the
tag really downgrade when it is passing through a city without any grade
separation? This would make it equivalent with other primary=* roads in the
city, although it is still part of the National route and a major link
in/out of the city. Should it be downgraded in the countryside when it is
just a 2lane road? Even though it is smaller it is probably still the most
significant road in the area outside of expressways.

- Metro Expressways and Metro Routes, if the National Routes will be tagged
with primary then it isn't easy to distinguish them.
In case of it not being part of a relation it isn't clear if it is a
National Route or Metro Route/Expressway in regards to the ref=* value.

Best Regards
Gabor Tanz
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/talk-ko/attachments/20220128/17d9bdaa/attachment.htm>