2008/10/8 Philip Homburg <[EMAIL PROTECTED]>: > I don't think this is about local interpretations. It is about having > safe defaults.
Agreed 100% > Of course, adding oneway=no to all trunk ways that do not have a oneway tag > can be done by a script. Clearly it could be - but it certainly _shouldn't_ be, unless that script can be confined to an area where it is certain that all trunks really are dual in accordance with local tagging norms. But I prefer this... > Another approach, that may also work for trunk roads is to write a consistency > checker that tries to detect this situation. > > A first pass tries to find roads with the same names, or unnamed roads that > are roughly parallel. Then report any road in that set that doesn't have an > explicit oneway tag. This is a lot safer IMHO, since (arguably) if we have mapped only one carriageway of a dualled road, it's more useful for routing software to be allowed to route both ways over it. With incomplete mapping, insisting on correct setting of oneway isn't all that useful. > I don't think that a relation should be used to imply oneway=yes. It's just > too risky. A dual-carriageway relation should. In a world where not even roundabouts are guaranteed to be one-way, we can at least trust a dual-carriageway to be so. > In a country where just all trunk roads are dual-carriage ways, defaulting > to oneway=no is just too risky. > > But you seem to care more about the burden of retagging some existing trunk > roads than about having safe defaults. Not at all. I don't care about the burden of retagging trunk roads. But I don't want the tail to wag the dog. The trunk tag was conceived for roads that are not inherently dual-carriageway. Established practice is to explicitly tag the special (and recognisable) case of dual-carriageways with oneway=yes. What I'm saying is that dualled section of trunk highways that are not yet explicitly tagged oneway should now be so tagged. Alternatively, we can introduce highway=gelbe_autobahn that implies oneway and bulk retag the German trunks. > On the other hand, given that localization is likely to happen eventually > anyhow, it may at some point become just a local decision. If we could reliably determine the nationality of a section of road I'd be a lot more relaxed about this matter (and others, like maxspeed). And once that day arrives, as it surely will, we can happily zap tags deemed on a regional level to be implicit. But we're not there yet. Dermot -- -------------------------------------- Iren sind menschlich _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk