[OSM-talk] open question about boundaries sharing nodes with ways or nodes

[Maarten Deen]

On 2015-10-14 09:49, Badita Florin wrote:

> Nodes 1856092007 [1] and 1856092002 [2] , which limit the following
> way [3] between such nodes. This way is a highway and at the same time
> is part of the relation of a boundary. This seems invalid since it
> merges two types of features on the same way instead of keeping a
> logical separation between two different things. Is this a valid way?

I have seen this more often. Is it a valid way of mapping? Sure, why 
not. Is it prudent? I don't think so, precisely because of your 
concerns:

> What if the highway is modified ? since the highway is not a legal
> boundary and just happens to overlap the real boundary, so if the
> highway  is changed for any reason, it will modify the boundary along
> with it.

That is why it you have to be very cautious in connecting different 
kinds of objects on the same nodes. I've seen this also on multiple 
occasions with landuses and roads. Not only does this make editting a 
bit awkward (more difficult to select the object you want to edit), it 
also is unclear what the meaning of it is.

> So what's the valid thing to do here? Duplicate the way to
> save the highway way and keep a way for the boundary separated?, I've
> found similar questions [4] by other users and they indicate it isn't
> valid but I need a more official argument because the user is upset if
> we remove this kind of ways from relations

I assume you are not doing automated edits? Then I would just remove the 
boundary tags from the road and remove the way from the boundary 
relation and draw/import the boundary new. To have two nodes on exactly 
the same spot is also not very nice. The JOSM validator will give a 
warning about that and then you risk that people are going to merge 
them.

Regards,
Maarten