okay, it seems that there is a need for a
machine readable tag that gives this information?

okay, I think dirt or not is not the criteria.
See highway=*

okay, macht sonst keiner, daher meine Frage.

hmm, the ref I638 appears on many roads
and they build a rather random pattern.
I used tertiary because the other roads
with ref I638 also have that, but as a local
you know better.

please review:
this changeset produced invalid tags like
highway=unclassified;service;tertiary
on way/199669988.
I've changed these tags to highway=tertiary,
but I think the names and refs look wrong

please review:
way/375806637 has now invalid tags
after a merge, e.g.
highway=unclassified;track
surface=paved;dirt
way/375806637

please review:
way/48405128 has the unusual tag
highway=unused_path
The note seems to say that this way is hard to use? Did you consider to use e.g.
smoothness=* ?

:-)

thanks, in the meanwhile I found this with google translator and changed the
way to highway=dismantled.
Hope that is okay?

please check:
what is the meaning of highway=verdge
for way/374995670 ?
Another changeset contained
highway=verge on node/3705504493.
Both are only used once in OSM

please review:
I've changed highway=proposal to the well documented highway=proposed
Bing is out-aged here, maybe highway=construction is better now?

please review:
I've changed highway=proposal
to the well documented highway=proposed.
Also proposal=* to proposed=*
See also
http://gis.19327.n5.nabble.com/how-to-tag-a-quot-highway-quot-that-doesn-t-exist-tt5857111.html

please review:
way/231880235
The tag highway=closed:residential
is rarely used. Consider highway=construction or just highway=residential with access=no and foot=yes if that matches better

Please review:
The tag highway=closed_path is rarely used and might be misunderstood as a path that forms a loop. What do you think about the well documented highway=abandoned ?

please review:
The tag highway=collapsed_footbridge is is rarely used. Consider highway=construction or highway=dismantled or highway=abandoned

please review:
way/43475450
The tag highway=collapsed is rarely used.
Please check highway=*
to find a documented value.
See also http://gis.19327.n5.nabble.com/how-to-tag-a-quot-highway-quot-that-doesn-t-exist-tt5857111.html

please review:
way/339268729
The tag highway=collasped
is obviously a typo, but even
highway=collapsed is rarely used.
Consider highway=construction or
highway=dismantled or highway=abandoned

please review:
the tag highway=concept
is rarely used, what do you think about
using the well documented highway=proposed, maybe in combination
with a note that gives more info about the planning stage?
See also http://gis.19327.n5.nabble.com/how-to-tag-a-quot-highway-quot-that-doesn-t-exist-tt5857111.html

please review:
Bing shows nice roads here now.
Some ways have
highway=residential and
construction=residential
The construction=* tag should be removed when the work is done.

please review:
way/254490127 has the tag
highway=construction;trunk_link
It is not clear what this should say.