On 28/07/2015, Marc Gemis <marc.ge...@gmail.com> wrote: > On Tue, Jul 28, 2015 at 4:14 PM, moltonel 3x Combo <molto...@gmail.com> > wrote: > >> That ideal doesn't match the practical reality. highway=primary has a >> very different definition between Ethiopia and Germany, by necessity. > > While they can be very different, a router should still be able to prefer a > primary road to navigate you from city A to B and avoid secondary or > tertiary roads. Of course in Germany it might be a smooth asphalted road > and in another country a sand road, but that doesn't matter. > > Are the current router properly routing over the Irish roads ? Can they > properly deal with the classification changes ? Or are those changes > ignored because the speed limits are properly tagged.
I was arguing against a worldwide unified classification. What you're worried about is only local classification : A router won't care about classification differences between far away places like Germany to Ethiopia. They just care about taking the best road in the area, and as long as OSM is locally consistent, this works. Even if a trunk turns into a primary for no physical reason and without additional helpfull tags like maxspeed, a router likely won't be thrown off and avoid the primary, because there's nothing better than the primary_which_used_to_be_trunk around. One routing error that came up recently is a trunk with a lower than typical maxspeed, and a trunk_link without a maxspeed tag. The router used its default idea of maxspeed for that link, and tried to use it as a shortcut. The router could have been smarter, but the data should have been more complete too, adding a naxspeed tag. _______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
