[Tagging] sidewalks and tagging for the renderer

[Martin Koppenhoefer]

I am coming back to a topic we had some time ago: sidewalks.

According to this page
http://wiki.openstreetmap.org/wiki/Tag:footway%3Dsidewalk

sidewalks should be tagged with
highway=footway
footway=sidewalk

While I agree that for complex situations it is helpful to have
dedicated geometry in OSM, I fail to understand why this should be
tagged "highway=*". Usually a distinct highway should be drawn only in
the case of a separated carriageway.

The suggested tagging is IMHO "tagging for the renderer". For tagging
sidewalks it would be sufficent to tag them with footway=sidewalk
without the highway-tag. In analogy to this tagging we would
optionally be mapping an ordinary street as dual carriageway and tag
each with highway=residential, oneway=yes, residential=lane.

New tags should be constructed in a way that doesn't change the
meaning of existing tags, but only adds detail to the existing meaning
in the case of a suggested tag-combination. In the case of sidewalks
dataconsumers that don't evaluate the footway=sidewalk tag will get
those highway=footway, which are tagged like this, wrong.

cheers,
Martin