[Tagging] Road classification

[Mateusz Konieczny]

On Wed, 2 Sep 2015 16:32:07 +0900
Andrew Errington <erringtona at gmail.com> wrote:

> > From this it sounds like this tagging in OSM is relying too much on
> > official classification rather than on real road importance.
> >
> >
> I have always maintained that this is the right way to do it.
> 
> Official classification is objective and easy to verify.
> 
> "real road importance" is purely subjective, open to argument, and
> inconsistent.
> 
> I think that for any particular country, the official classification
> hierarchy should be mapped on to the OSM hierarchy.  If this is not
> sufficient for accurate routing then mappers should add more
> information, such as lanes=*, maxspeed=*, width=*, traffic lights and
> so on.  Routers can 'prefer' highways that are higher up in the
> hierarchy, and then penalise sections of the routes that have narrow
> roads, fewer lanes, or lower maxspeeds.

So footway that is National Road (happens in Japan, already mentioned
in this thread) should be tagged as highway=trunk?

Generally following official classification is a good idea (otherwise
it will be inconsistent) but some exceptions should be expected.

Also, there are many ways to map official classification on to OSM
hierarchy. At least sometimes the simplest form of mapping will not be
the best one.