[Tagging] Roads with no speed limits
colin.smale at xs4all.nl
Sat Sep 3 15:30:06 UTC 2016
On 2016-09-03 16:39, Martin Koppenhoefer wrote:
> 2016-09-03 15:57 GMT+02:00 Colin Smale <colin.smale at xs4all.nl>:
>> That will only work if the road types are mapped correctly to their official legal status, and not to how they appear.
> There not the one "legal status", at least not in Germany. There's the maintainer of the road, e.g. "Bund", "Land", "Kommune" (national, federal, comunal), and this is how road numbering works. This is the most visible legal status, but it doesn't allow to deduct specific speed limits. Then there is the road class according to technical specifications, consisting of 3 functional classes (connective, distribution, residential), 5 "category groups" (A, B, C, D, E) that have to do with the aforementioned functions and the context (inside and outside built-up areas, lined with buildings and not) and there are 6 levels of connectivity (or importance of connection). These are defined in the 1988 RAS-N (Richtlinien für die Anlage von Straßen - Netzgestaltung), , which is now obsolete, but according to which many of the current roads have been planned and built. They have been superseeded by the RIN (Richtlinien für die integrierte Netzgestaltung)  which are somehow similar in
content, at least for this discussion here.
> These technical rules are the actual important classes / legal status, that would have to be known, but not even their existence is commonly known, they're stuff for civil engineers.
> Laws and rules are typically limited to national borders, if we were to structure OSM according to them, we would not have the nice global dataset we all love, we would have a collection of fragmented national solutions, incompatible between them.
Ergo: map all the speed limits explicitly, and don't rely on the road
type to infer them. Then only one person has to jump through all the
As for the fragmented national solutions, I think that is exactly what
we have and exactly what we want. Modelling all the traffic laws in the
world into a single data model will result in such a complex set of tags
- you don't want that, really you don't. Think of the definition of
something simple like a bicycle - is a tricycle or a unicycle included?
What about trailers? Electrically assisted? Different rules for
competition riders? Does a maxspeed apply? All this is going to differ
OSM has always valued local knowledge and local solutions, as long as
they are not too far from the generic model i.e. as long as they don't
Sometimes we seem to be permanently scared of documenting anything for
fear of upsetting some future mapper. The subject of national defaults
has been discussed before and I seem to recall there was a certain level
of support; yet there is no real progress towards its implementation.
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