[josm-dev] Reversing of node tags

[Matthias Julius]

Frederik Ramm <frederik at remote.org> writes:

> Hm. There is for example "highway=incline" and "highway=incline_steep", 
> used more than 1600 times nodes in Germany alone. They usually come in 
> tandem with "incline=xx%" which would have to be turned into 
> "incline=-xx%" when the way is reversed.

I would consider those tags on nodes as broken.  These should all be
way tags.  I would propose to change Map Features in this respect and
have the JOSM Validator, Maplint & Co. put warnings on nodes where
they exist.  An incline that "fits" into a node is either so low that
it is not worth tagging at all or is so steep that it should better be
tagged as cliff. ;-)

Actually highway=incline[_steep] should be discouraged alltogether.
http://wiki.openstreetmap.org/wiki/Key:incline mentions incline=up and
incline=down for cases when the exact value is not known.  Also,
inline=* can be used for other things beside highways.

>
> You are right in saying that this is ambiguous in theory. In practice, 
> of roughly 1650 occurrences in Germany, 1441 were used by only one way; 
> 167 were used by two ways (every case I checked was simply where one way 
> ended and another began), and 34 were used by more than 2 ways (the most 
> adventurous one being http://www.openstreetmap.org/browse/node/302422098 
> but this looks like someone has misunderstood something). The remaining 
> ones were not used by any way.

Even in the case where the node simply connects two ways there is a
problem if one of them gets reversed.

>
> I don't even known if JOSM handles this correctly at the moment, but if 
> it does then it should perhaps not be broken?

JOSM currently looks for left/right, forward/backward,
forwards/backwards and oneway tags, values and relation roles.

There is no reversal for highway=incline.  All JOSM could do is put
out a warning.

It certainly makes sense to include incline=* - most of which are on
ways anyway (according to OSMdoc).

Matthias