[Tagging] winter tyres

[Kevin Kenny]

>>> http://wiki.openstreetmap.org/wiki/Good_practice#Don.27t_map_your_local_legislation.2C_if_not_bound_to_objects_in_reality
>> if there’s a sign “winter equipment required” it is bound to an object in reality.
> I'm not disputing that. I was commenting on Kevin Kenny's pointing out the
> "don't map your local legislation" rule in response to your question whether
> "we want to tag "winter equipment required" and this means
> different things in different jurisdictions, or if we set up a series of
> more atomic tags that spell out the implications of "winter equipment"."
>
> Bearing this rule in mind, it seems logical to only use
> "winter_equipment_required=yes" or "winter_equipment_required=<time_range>"
> (if the traffic signs specifies a time range), rather than tags for all the
> implications of winter equipment.

Exactly what I was trying to say. The sign reads, 'winter equipment required'
(or whatever). The local legislation defines what that is, and could be changed
by the legislature without needing to replace the sign. The sign exists
on the ground. It says what it says.

I can understand the argument that a navigation system might
conceivably want the definition in machine-readable form, but
eventually, we get to where we want a navigation system simply
to ask the driver, "the database says the road is restricted, do you
want to go there?" (as osmand does for private ways now). The old
paper road maps that used to be ubiquitous at gas stations usually
had some sort of symbol that represented "limited purpose or
seasonal road - inquire locally for conditions." We eventually
reach a point where "warn the driver and ask for confirmation"
would be the right answer even in OSM based systems.
It just isn't possible to encode all the conditions that the
human imagination keeps inventing.

Off topic: (feel free to stop reading here)

For that reason, there are a fair number of miles of wilderness trails
that I've entered, where I haven't troubled to try to invent tagging for
the local legislation, "snowshoes or skis required when snow depth
in treadway exceeds eight inches," even though that rule generally
appears in the long list of the rules at the trailhead.  It just felt too much
like "mapping the legislation" rather than "mapping the thing on the
ground."

Even further off topic: (this next bit I know is contentious)

That's why I've still not abandoned, "access=permit".
There are a lot of signs in my area that read, "access by permit
only", (where other signs from the same agencies say "entry
forbidden", or "public access allowed for the following purposes").
It's a thing that's visible on the sign. The details of the conditions
under which a permit is granted generally are NOT visible in
the field, although generally the signs have contact information.
I've been silent on that subject for a while just because I haven't
had time to Wikify a formal proposal. Too many other projects.