How to tag a fence on top of a retaining wall?

I often see fences on top of retaining walls but I’m not sure how to tag them: I made a way with the retaining wall and another one on top of it (layer=1) with the same position, but JOSM warns me that there are two ways with the same position. Should one use something like barrier=retaining_wall;fence?


I think, maybe ‘barrier=fence’ + ‘fence_type=concrete;bars’?

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That’s how I do it and thoroughly ignore JOSM validator on this special case and any cases where 2 different features are in the same position. For instance a horse riding ring and railing around it.


Yes, but we lose the information about the retaining wall: here the wall is much higher on the other side because the ground is significantly lower.

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Warnings do not automatically mean something is wrong/incorrect. They should probably make you double check what you’re trying to do, but if you’re sure it’s correct it’s fine to treat them as false positives.


If not, I think you can draw the fence by floating it very slightly inside the retaining wall.
Screenshot 2023-06-28 at 15-49-18 오픈스트리트맵

this is a different configuration though

As a follow on for this, if there is something that is always right and we are pointing it out, please open a ticket with (a) a location with the false positive, (b) an explanation for why it is a false positive, and (c) links to supporting documentation indicating that it is, in fact, correct.

I’d really like to reduce the false positive and false negative rates.