2012/10/15 Johan C <osm...@gmail.com> > I think there's some confusion here. Imagic's question was on a motorway > example.
Where did you get this from? Sure, he referred to a picture with the model of a motorway, but he esplicitly said "consider only section 5". We're not talking about that section 5 *on a motorway*. Also, your distinction motorway / non-motorway is meaningless. Motorways are usually mapped with two separate ways because they, uh, are physically separated carriageways. There's a guard-rail, or a new jersey barrier, sometimes even a ditch or a gap between bridges. There used to be (at least in Italy) motorways with a single carriageway, where lanes were separated by a painted line; this was not a physical separation and would be tagged as a single way. > 2. An OSM'er started a discussion on a German page: > http://wiki.openstreetmap.org/wiki/DE_talk:Tag:highway%3Dmotorway_link. > It seems that the current wiki on motorway_junctions requires the start of > the split to be at the beginning of the deceleration lane. "In der Regel > ist das der Punkt, an dem die Ausfädelspur beginnt oder die Auffahrt von > der kreuzenden Straße abzweigt." Thus, the current osm tagging standards > imply that Imagic's option a is wrong (option b too by the way [?]). > As I said above, for short sections of legal separation (white paint) immediately followed by a physical separation (the guard-rail) I am in favour of anticipating the split, just like it has been suggested in the discussion you talk about. What I'm modeling this way is that there is in fact a physical separation, and I'm just being imprecise about where the separation starts. I advocate this imprecision because it has advantages on the topology of the split (Y-shaped rather than T-shaped), and an early indication is better than a late one. > 3. You could have guessed, but i'm in favour of the way OSM is being used > at this moment, so option b. My arguments are about the same as Colin's. > And because I like the current tagging as shown in above examples. > You may be confused about this. The "current tagging" is in fact option A: where the carriageways are physically separated (or at least a single continuous strip of asphalt is divided by a physical barrier), draw two ways; otherwise, a single one. Your motorway examples are examples of option A. The fact the we split ways entering a large roundabout is my bending of option A: the way is split where the white paint begins (instead of where the kerb with grass begins) for better topology. I fail to see where a Main Street with no barrier in the middle is drawn as two ways (don't bring me a couple of examples, name a country or a community that does this). Regards, Simone
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