> > if the way is "layer=0" and the bridge is "layer=1" there is a ramp. > > A bridge crossing any other way should be always tagged with layer=1 (or > higher). In fact, the renderers could easily take "layer=1" as a default > for bridges, as they are usually on top of something. > > > if the way is "layer=0" and the bridge is "layer=0" too > > (the crossing way under is "layer=-1", digged) > > then the bridge has no ramps. > > Something with negative layer has to be a tunnel.
I think you're both overinterpreting the layer tag. As the concerning ways do not cross each other, their relative layers don't matter. And I don't see a reason either why a negative layer should imply a tunnel. > Bridges are useless if > there is a tunnel. Do not tag bridges as "layer=0" just because there > are no ramps. The layer tag is to help a renderer put the ways in the > right visual order - not to indicate whether or not a way is elevated or > not. Do not tag ways as "layer=-1" just because they are below the > general earth surface (such as rivers). This may be a good idea, because it keeps the effects of the layer constrained to the short bridge instead of the long river, thus helping to avoid mistakes. But I would not see it as wrong. Because there are widely varying interpretations of layer, I wrote down how I understand it: http://wiki.openstreetmap.org/wiki/Talk:Key:layer Comments are welcome. Regards, Marc -- NUR NOCH BIS 31.01.! GMX FreeDSL - Telefonanschluss + DSL für nur 16,37 EURO/mtl.!* http://dsl.gmx.de/?ac=OM.AD.PD003K11308T4569a _______________________________________________ talk mailing list [email protected] http://lists.openstreetmap.org/listinfo/talk
