2013/1/31 Martin Vonwald <imagic....@gmail.com>: > Hi! > > I'm looking for some alternatives to map tunnels and bridges that > contain several ways. I'm not really happy with the proposed relation > [1]. Is there any other approach for this? I'm asking myself why don't > we simply map the outline of the bridge/tunnel (the latter may be more > difficult to obtain), tag it with something like structure=bridge (or > similar, maybe even building=bridge), bridge=<type> (if necessary) and > layer=x. Connect the ways running over the bridge to this structure, > use the same layer tag and you're set. It is after all a physical > object, so why don't we map it as such? I simply don't see any reason > for a relation here.
+1, drawing the outline seems a good approach as it permits to group visually (and topologically) different carriageways running over the same bridge (as opposed to two parallel bridges). Actually a "classic" bridge will often have several outlines when the abutments are mapped separately, and then you would use layer-tags and maybe would want to also add the abutments to the bridge-object (in this case a relation might be needed). For tunnels I am not sure if there are situations with several carriageways in the same tube (in this case a common outline made sense IMHO, while 2 parallel tubes should be (IMHO) considered 2 tunnels. Tunnels also have the practical problem that you can't see their inside on aerial imagery and GPS doesn't work inside, but this is a different issue aside from tagging. Whether "building" is a nice key might be disputable (a bridge technically isn't a building, but a technical structure, on the other hand I have always argued that "building" in OSM is a generic tag for all kind structures and not only those intended for humans to live inside), but personally I'd approve it. If we decide to use building=* for bridges the * should be always the same value (e.g. "bridge") and not building=draw_bridge etc. (these details like bridge typology would go into subtags, allowing easy filtering of the bridges if you don't want to render them as buildings). These bridge-objects would also allow us to tag in an easy and standard way stuff like ref-numbers and bridge names (i.e. with "ref" and "name" and not requiring stuff like "bridge_name"...), have a common object to link WP-articles, etc. Cheers, Martin _______________________________________________ Tagging mailing list Tagging@openstreetmap.org http://lists.openstreetmap.org/listinfo/tagging
