[Tagging] Mountain passes

Ulf Lamping ulf.lamping at googlemail.com
Sun Feb 13 21:28:26 GMT 2011


Am 13.02.2011 20:57, schrieb john at jfeldredge.com:
> I guess this partly comes down to the questions of how you define a way, and how you define a pass.  If a particular pass becomes little-used, because a tunnel or a lower pass provides an easier way to get past the mountains, does that make it stop being a pass?  What if the pass is a boundary between two nations, and the border crossing is closed because one or both nations don't maintain a customs station there?  Does that make the pass stop being a pass, in the geographic, rather than political, sense?
>
> -------Original Email-------
> Subject :Re: [Tagging] Mountain passes
>> From  :mailto:dieterdreist at gmail.com
> Date  :Sun Feb 13 13:36:08 America/Chicago 2011
>
>
> 2011/2/13 Nathan Edgars II<neroute2 at gmail.com>:
>> According to http://wiki.openstreetmap.org/wiki/Key:mountain_pass "passes
>> only make sense on ways". But it's possible to have a pass with no way
>> crossing it (not even an informal footpath) or with multiple ways crossing
>> (a dual carriageway, or parallel highway and railway). How should these
>> cases be handled?
>
>
> no, it is IMHO not possible that a pass has no way that crosses it,
> otherwise it wouldn't be a pass.

In the narrower sense you are correct, but:

http://en.wikipedia.org/wiki/Col_de_Bretolet

A pass (french: Col) that has no way to either side, but a way over a 
ridge from the Col de Cou ;-)

> If there is more then 1 one way I
> guess you would have to tag all of them.

Especially in the U.S., I've seen some dual carriageways with two pass 
nodes, e.g.:
http://osm.org/go/T2U0CV8Ye-?layers=O

> Maybe natural=pass (or mountain_pass) on a node might be more logical
> for the feature if you bear in mind that the wiki suggests to tag ele
> with it.

The underlying problem "what makes a pass a pass" is *very* difficult to 
answer, e.g. there's a lengthy Wikipedia discussion about it. If a pass 
is closed due to political differences but there's a way over it, this 
is an easy one (mountain_pass=yes and access=no).

The difficult question: What is generally a way in this regard? If you 
can travel the pass by car, 4*4, horse, MTB, hiking, via ferrata or 
extreme sports?

If you read the wiki page, it started in 2007 with highway=pass, so you 
can see that I (and others) basically had roads in mind when I've wrote 
it (and no one at that time seemed to even mention passes with no way).

In practice today, a lot of nodes with mountain_pass=yes are tagged, 
where you don't see any way nearby (maybe from imports?), and a lot of 
nodes on hiking trails, roads, etc.

So today in OSM a mountain_pass=yes denotes the geographical feature in 
the wider sense (german: Scharte, Sattel, Joch, ...), not the "narrow 
definition" of being a passage on a way.

Regards, ULFL

P.S: What bugs me more is the (not so un)common practice to put the node 
near the way (where the sign is?) and not exactly on the road. This 
makes it difficult for renderers to detect the kind of way a pass 
"provides" ...



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