On Thursday 13 August 2009 00:31:23 Lauri Kytömaa wrote: > Lambert Carsten wrote: > >sense. Even though the smaller road ends at the edge of the larger road > >not the middle of the road. > > Inside the crossing area the roads overlap, neither ends there - you're > on both roads. But you're not on the bridge that starts only several > meters away - or inches away if you're already moving towards the > bridge. > > Taking the canal bridges mentioned previously: if you draw the > riverbanks/canal edges, it has been the recommendation (I'd have to dig > the talk list archives for that) also that the bridge=yes starts and > ends at the points where one can get under the bridge - at the water's > edge, meters away from the ways marking the roads running parallel to > the canal. It isn't about inches or even meters. It is about representing reality in such a way that renderers, routeplanners whatever can do interesting things with the data. Starting the bridge at the edge of the water is not a good recommendation because it has to be made clear to whatever program parsing the data that it is ok to have a road going 'through' water because we have a bridge. Just for practical editing reasons the bridge node should not be too close to the water edge. > > One thing about the same layer check occurs sometimes: a motorway link > road joins the motorway right at the point where the bridge starts: most > notably the case where the road markings indicate three lanes on the > bridge and only two (+1 approaching but still separate) up to the exact > point where the bridge starts. We can make the connected node something > other than the point where the lanes come into contact (the acceleration > lane's hundreds of meters long anyway, but that would need some kind of a > note to be consistent - at least once more people start to get to that > level of detail. If I understand this example correctly it is another example that the 'rule' as rule is wrong.
On Thursday 13 August 2009 11:51:36 Jochen Topf wrote: > On Wed, Aug 12, 2009 at 10:58:36PM +0200, Lambert Carsten wrote: > > > That often leads to inconsistencies, but > > > inconsistent is not necessarily bad. > > > > Exactly, no need to 'force' junctions to have connecting roads on the > > same layer. If you really believe in the 'middle of the junction theory' > > let us be inconsistent with that one and help mappers clean up real > > issues rather than adding titsy bits of road between junctions and > > bridges. > > I didn't say anything about "titsy bits". If you only add this to work > around the Keepright message, that doesn't make any sense. It only makes > sense to add a non-bridge part of the way, if it actually is large enough > to make a difference when rendering. Well sadly while I have been discussing this here that is exactly what has been done. (No one's fault, it's the way things go.) Most of the bridges in Amsterdam now have 2-3m connection bits (less than half the width of most roads) between the bridge way(s) and the junction (example: http://www.openstreetmap.org/?lat=52.36607&lon=4.88279&zoom=17). Hopefully this will not cause (too many) other issues in the future. Often the renderers try to insert the name of those bits separately. I dread that next people will start 'cleaning up' that by removing the name there after which Keepright will (correctly) mark it as a street with no name.... :( I hope I am wrong, I really do. > > > > And if we get better software or more > > > detailed data or want to support new uses, we'll change things around. > > > > Can we agree on getting rid of the "Right" and especially "Wrong" texts > > that deal with this issue in the Map Features and give some advice like: > > "Often bridges/tunnels will not connect directly to a junction in which > > case you should/can (?) add a piece of road connecting the two." ? > > The page could definitely have a more thorough description of the problems > with either way of mapping and give some advice, when each makes sense. > Feel free to add this. Your sentence above sounds like a good start to me. Well thanks for that! Consider it done. btw I noticed there are some translations regarding this issue. Is there a way to inform them or is it their job to keep an eye on the English version? > > Jochen Lambert Carsten _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk