2017-08-31 13:49 GMT+02:00 André Pirard <a.pirard.pa...@gmail.com>: > > - The Belgian Flemish community wants to tag *maxspeed*=* > <https://wiki.openstreetmap.org/wiki/Key:maxspeed> on every road > instead of using a default. Is this a new specification and where is it > written? Must that now be done in every country? > >
We are doing this in Italy for many years now, and it is quite robust and reliable. We are adding the source:maxspeed tags additionally to explain whether the maxspeed is explicit (sign / road marking etc.) or implicit (usually derived from a zone like "inside a settlement", "on a motorway", "outside of a settlement", etc.). In all countries I am aware of you can't reliably detect default limits without knowing if the road is inside or outside of a settlement, which is typically not dependent on the actual settlement but on street signs that tell you when you enter or leave a (traffic code related) settlement. It has also proven useful for maintenance and verification to map actual speed limit signs (traffic_sign=maxspeed, maxspeed=n ) at the side of the road (to have the direction stored). > Either the defaults are in the OSM database and it takes just a routinely > map fetch to get them all updated timely, > or each other router (GPS) writer implements them each their own way from > various random other files. It's not well clear how contributors ca update > all those files instead of OSM and it typically needs a full software > update for each little default change, depending on writer's availability. > it really depends on the kind of "default" you are after. What about a maxspeed=50 sign in Germany inside a settlement (i.e. it is a sign which states the default). If the law for the default changes, this 50ies sign will not have to change (unless they are going to modify the sign). If the road is simply tagged with "highway=tertiary" you can't know whether this is incomplete data, or the mapper had a lot of defaults in mind like lit=yes, lanes=2, surface=asphalt, maxspeed=50, sidewalk=both, oneway=no, smoothness=good, etc. (assuming a smaller road in a city). You can't even know whether the road is (legally) inside a city. I guess you would have to define really complex defaults / processing to cater just for the more used properties. A tag like source:maxspeed allows to change all speed limit defaults in a country at once because they are explicitly marked as defaults. Cheers, Martin
_______________________________________________ Tagging mailing list Tagging@openstreetmap.org https://lists.openstreetmap.org/listinfo/tagging
