building=bridge should be considered a special case of man_made=bridge. Tagging both high-level tags is a violation of One_feature,_one_OSM_element.--Jojo4u (talk) 12:23, 29 September 2016 (UTC)
- Wondering if building=bridge was such a good idea - the building in the example picture clearly has a different purpose than being a bridge. If we see a school built the same way it would make more sense to use building=school and either man_made=bridge or just only layer=1 and covered=* or something similar for the road bellow it? But if we would use man_made=bridge for building=school it should not be wrong to use it for building=bridge, sometimes it may be two features in one. RicoZ (talk) 14:06, 2 October 2016 (UTC)
- I'm also not happy with this. The example picture does not function as bridge but is built like one. It spans the motorway to save space. I'm strictly against using man_made=* and building=* together, since this is semantically problematic and leads to unpredictable rendering (different style for man_made=bridge+building=*).
- What properties does a building=bridge inherits from man_made=bridge? I guess it's the exception we where talking about in covered=*?: The bridge as a whole is both besides (support structure) and over features which are under it. Nevertheless we use layer=1.
- I see building=bridge most used for connections between two buildings (https://en.wikipedia.org/wiki/Skyway). I guess we should look at how to tag this best and not at some fancy buildings like the example.
- I'd say a skyway is considered building if it's inside is considered indoor. Otherwise it's a man_made=bridge+bridge=covered.
- About layering: If the skyway is part of building (building:part) and a highway=* goes below it we have three possibilities:
- layer=1 for whole building (this does not mean the building is detached from earth)
- layer=1 for building:part
- layer=1 for both
- layer=-1 for highway
- covered=yes for highway
- I's all about the "under/besides" debate as well here :)
- --Jojo4u (talk) 15:04, 2 October 2016 (UTC)
- ... enough possibilities to do it properly. I think a layer=1 is not sufficient to express that it is a bridge (too many objects have that accidentally) so either bridge or covered or tunnel should enter the scene. The exception could be building:part where it is more expected that some levels like 0 may be missing.RicoZ (talk) 21:05, 3 October 2016 (UTC)
- One problem with adding special meanings to building values in particular is that 90% of the values are just niche information about the original use of a building, which is arguably more suited for historical mapping – and then suddenly there is one that needs special treatment in renderers. It's also a relatively rare case, where saving few extra seconds during mapping does not justify special treatment. Let's keep the rules as consistent and simple as possible please. --Tordanik 18:43, 6 October 2016 (UTC)