> those two would meet in point A, from which the branch line sets > off/rejoins the core line. So a hypothetical future route-finding > algorithm would follow different_route to its end, upon meeting core line > it would continue along.
It just doesn't work. Having an unordered relation or even mapping both directions within the same relation leads to ambiguities. Just two examples: http://www.openstreetmap.org/?lat=51.29314&lon=7.21791&zoom=17&layers=B000FTF Bus service 618 southbound comes on the "Gennebrecker Str." from the north, loops into "Agnes-Miegel-Straße" and then proceeds on the "Gennebrecker Str." to the south, always. 618 northbound passes on the "Gennebrecker Str." from south to north only. Oxmoa suggests two relations <rel> <tag k="ref" v="618"/> <tag direction="southbound"/> ... <member ref="northern Gennebrecker Str."/> <member ref="Agnes-Miegel-Straße"/> <member ref="southern Gennebrecker Str."/> ... </rel> <rel> <tag k="ref" v="618"/> <tag direction="northbound"/> ... <member ref="southern Gennebrecker Str."/> <member ref="northern Gennebrecker Str."/> ... </rel> Now I would like to see how you discriminate this case from the case where 618 passes through the loop in both directions (so does line 624) if you don't have an ordered relation. In Oxmoa it is very simple: you map what the bus does. Second example http://www.openstreetmap.org/?lat=51.255881&lon=7.150008&zoom=18&layers=B000FTF Line 643 passes in both directions from "Morianstraße" on the left to "Islandufer" on the right. But in eastbound direction, it passes through platform 5, in westbound direction is passes through platform 4. This is important, because buses in both directions are at the stop at almost the same time. In Oxmoa, it is again simple and intuitive: <rel> <tag k="ref" v="643"/> <tag direction="eastbound"/> ... <member ref="Morianstraße"/> <member ref="platform 5"/> <member ref="Islandufer"/> ... </rel> <rel> <tag k="ref" v="643"/> <tag direction="westbound"/> ... <member ref="Morianstraße"/> <member ref="platform 4"/> <member ref="Islandufer"/> ... </rel> > Also, there is at >present no provision for implementing the "time" of bus lines, so at present >one could be advised to take a night line at daytime. See http://wiki.openstreetmap.org/wiki/Opening_hours (the server is currently down): just add something like "Mo-Fr 5:00-21:00" to indicate when the service is operational. Nonetheless, there are still things that Oxmoa leaves open. For example, there is no specification how to store approximate journey time. But the usage of ordered relations and the separation of directions is one of the strengths of Oxmoa, not a weakness. Concerning Potlatch ... It's just not open. You can easily contribute to JOSM by writing a plug-in or even submitting a patch. Potlatch makes the life for the programmer much more difficult; it has no defined interface for extensions. By the way, it doesn't work in a densely populated area at all. The reason why I have written the plug-in for JOSM is that I wanted an easy way to map bus lines, not a personal preference of JOSM. I'd suggest that we use the discussion page http://wiki.openstreetmap.org/wiki/Public_Transport of the wiki once the server is back again to write a consistent, easy-to-use and easy-to-implement standard. Cheers, Roland _______________________________________________ Talk-transit mailing list Talk-transit@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-transit
