As you may know in the major part of Lake Constance there are no national boundaries and it is governed by all three countries bordering the lake (Austria, Germany and Switzerland).
Note that there is no conflict about the current state of affairs and Wikipedia is wrong to imply that there is one. There are differing ideas about how to the draw the borders if there were negotiations and subsequently an agreement, but currently everybody is perfectly happy with the status quo.
It should be further noted that the current common administration does not imply that any one countries borders expand to cover the whole lake, there are simply no borders there.
This poses a problem as we currently need to somehow close the boundaries, not just for rendering but for all kind of analysis purposes. Which leads to the current solution in which we have clearly incorrect borders in the middle of the lake. This works for the technical side of things, but results in a aesthetically very unsatisfactory rendering on most maps of borders that don’t exist.
I could start a poll now on some of the potential ways this could be fixed, for example swisstopo labels the segments in question as a “technical” boundary and doesn’t render them, but lets hear if somebody has a better idea.
One idea could be to have overlapping borders showing the entire lake as part of all three states if all states have some jurisdiction over it?
Then another idea would be to draw borders following the shoreline, or some set distance away from the shoreline like 1 km, and have the middle of the lake not be inside any national border?
Not too long ago, a wise old man said that since we can’t model the actual situation in OSM, the current solution is just as good/bad as any other and has the advantage of being simple and producing complete boundary polygons.
The same gentleman also said that this was by no means the first time this issue had been raised.
If there are no borders in reality but we want some in OSM there is no way to avoid showing borders where there are none.
The present solution is as good as any other one imo. The only alternative I could imagine is to understand the lake as some kind of international water body and draw the borders along the shorelines.
I find asking for a “better idea” without providing that thread as context and then dismissing suggestions outright a little rude, but maybe that’s a cultural thing…
I’d suggest adding the tag disputed=yes to the current border segments (it’s not really actively disputed but there is no agreement on the currently mapped border either). This allows data consumers to avoid rendering the unclear section of the border.
Median line is a good default assumption if no-one is claiming otherwise (this is also the default for EEZs in maritime context), so I wouldn’t change that.
That doesn’t and didn’t imply that we couldn’t improve OSMs modelling toolchest to include a solution for this situation, just that none of the currently available ones improve the modelling.
So then https://www.openstreetmap.org/relation/51701 would follow some boundary=administrative and some boundary=condominium? I guess if we are desperately unhappy with the current state of affairs, that could work, as long as we give all users of national boundaries from OSM plenty of notice
