On Sun, Oct 3, 2010 at 11:16 AM, Ralf Kleineisel <r...@kleineisel.de> wrote: > On 10/03/2010 05:04 PM, Anthony wrote: > >> Maybe it's just because of where I live, but I don't see how it would be. > > Well, where I live (Germany) we have a legal limit of 100 kph on roads > outside of cities, motorways excluded. This legally applies even to > small roads if there is no sign indicating a lower limit. On many roads > you can achieve this speed, too. But on the other hand we have lots of > narrow, twisty country roads where a normal driver does not go faster > than 60 kph. In the Alps it is even more drastic. For estimating the > time someone will probably need to drive along a road this information > would be very helpful.
That seems like a reasonable argument to me. I'd question whether or not we'd want to call it "average speed" though. If we limit the use of it to roads which are structurally of a nature which doesn't allow safe driving at the speed limit, I don't think we'll get into those problems I mentioned above. What I'm most hesitant about is if you factor in traffic. Traffic is too transient (and contains too much time-specific data) to be put in OSM, unless the whole structure of OSM is redesigned. > Even if we introduce this tag, nobody is forced to ever use it. That's one of the big potential problems, actually. If you have average speed information on some ways, and no average speed information on other ways, there's going to be a systematic bias in the routing algorithms either to use or to not use ways with average speed information. (Unless the routing algorithm can perfectly predict the average speed of ways without average speed information, in which case the average speed information is useless anyway.) Unless the tag is used consistently, at least consistently across any particular geographic area, it's going to be more trouble than it's worth. _______________________________________________ Tagging mailing list Tagging@openstreetmap.org http://lists.openstreetmap.org/listinfo/tagging
