Florian Lohoff píše v St 20. 05. 2009 v 21:39 +0200: > On Wed, May 20, 2009 at 11:59:05AM +0100, Radomir Cernoch wrote: > > 1) Every road is by default 'rural' road (speed limit 90 km/h). > > 2) Every highway has speed limit 130 km/h by default. > > 3) If a road is inside a polygon tagging the city limits, > > then its speed limit is set to 50 km/h. Such polygon might be tagged > > by 'place', but the actual name of the tag is not important here. > > 4) If a road has different speed limit from rules 1) - 3), it is tagged > > with 'maxspeed=...'.
Hi, I'm not sure whether I completely understand you. Please correct me, if I misinterpret you... > The problem with implicit speed limits is that one day someone will rely on > your output and probably just someone only forgot to map at that end of the > road. The best thing to do is to make maxspeed/zone explicit only. The idea is not to create a node "here starts city" and a node "here ends the city". The idea is to create a polygon which defines the border of 50 km/h speed limit. The problem of forgotten "end node", which causes cities to leak all over the planet, does not apply. > The advantage of a traffic "zone" to maxspeed is that one can derive the > source of the speed limit (and possibly other limits)... By "traffic zone" you mean a tag "zone=XXX" on each individual road in the city? I'm afraid that such system is very prone to forgotten tags. If you use a polygon around a city, you can also derive the source of the speed limit. Rules 1) - 3) mean that being "on highway"/"in city"/"outside city" is the main limitation. Applying rule 4) means there is a physical sign that causes the regulation. > ...In Germany we have a very > widespread "zone 30" culture where not all streets have individual speed > limits > but rather the sign limits the speed until you pass the end sign - probably on > a very different road. Much like city limit signs. Yes, in the "polygon" system you would encircle the whole area and every road inside of it has automatically 30 km/h limit. > The problem now is that you cant actually work with polygons as for > example a motorway could pass over a zone-30. Sorry, I maybe didn't make myself clear. "Polygon" rules do not apply for motorways. Is there any country, where a highway inside a city has different speed limit from the highway outside of the city? Even if yes, this can be specified in the set of country-specific rules... I can imagine a situation, where a normal 50 km/h road goes through the middle of a zone-30. Then there are two options: 1) You split the zone-30 polygon into 2 polygons. 2) You tag the 50 km/h road with "maxspeed=50". Yours, Radek _______________________________________________ talk mailing list talk@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk
