[OSM-talk-be] sidewalk as ways or tags

[Renaud MICHEL]

Hello

I have recently had a small edit war with user nondidju regarding my tracing 
of sidewalks as separate ways, see
http://www.openstreetmap.org/browse/changeset/7461451
http://www.openstreetmap.org/browse/changeset/7528743

He argues that the mapnik rendering of this show how irrationnal it is 
(which is a personnal preference on which I differ) and that those should be 
tagged on the main way.
I personnally think that it is more topologically correct, having a parallel 
footway (where there exists ont) and foot=no on the main road, as on 
important roads you may not cross anywhere, but only where a crossing 
exists, so a separate way allow for correct routing for pedestrians.
As an example, on this way
http://www.openstreetmap.org/browse/way/57687924
you may simply not cross the road between the bridges.
(I don't create parallel footways for every road, only those where I 
consider it unwise to cross anywhere)
Another example
http://osm.org/go/0EqqLNEt0--
Here you may not cross the road on sides of bridge "Albert 1er", you may 
either take the tunnel on the right side, or go to the traffic signal on the 
left.

From a recent discussion on newbies@
http://lists.openstreetmap.org/pipermail/newbies/2011-March/006340.html
it seems the recommanded way to tag those is to use a footway tag on the 
main road, but with this, routing engines have to do a preprossing to 
recreate the topologically correct ways, or have a more complex algorithm 
taking into account on which side of the road you are walking and where you 
way cross.

And the problem is harder for roundabouts, see for example this one
http://osm.org/go/0B964M9V@--
and his brothers along the motorway
http://osm.org/go/0B965o7BK--
how would that be represented with only tags on the roads?
This will end up splitting the ways many times.

Now, I agree that bridges don't look very well on the rendering, but that is 
already a problem when you have separated roads on the same bridge (see 
previous link), and that is a renderer problem, maybe missing a "bridge bed" 
information to know that the ways share the same bridge.
I saw a related discussion some month ago, but I don't this it ended with a 
way to tag it.

I didn't find anything related on the pages of WikiProject Belgium (but I 
may have missed it).

So I would like to have your thought and opinions on the matter.
I think tracing ways to represent sidewalks for roads you should not cross 
anywhere adds valuable informations, bu if everybody is against it I will 
retag it as footway=left/right/both/none where appropriate. cf
http://wiki.openstreetmap.org/wiki/Proposed_features/Advanced_footway_and_cycleway

thank you
-- 
Renaud Michel