[OSM-talk] Name tags on sidewalks and on cycleways next to a road

Lauri Kytömaa lkytomaa at cc.hut.fi
Mon Mar 15 09:16:06 GMT 2010


Some places are mapped thoroughly enough that we're adding sidewalks,
and cycleways on the sidewalk (or Copenhagen style cycleways, as
they've been called on this list) as separate ways. Generally these
don't have a separate name. At least when the cycleway/footway
deviates away from the road, even if only for some meters, other
places have them drawn as such, too.

Having read the oldest talk archives few years back, it has been a
common understanding that only the road, which these cycleways run
along, is named with name=*, yet it's not explicitly stated anywhere.
Some disagree, as I have learned in the last half year.

I'm writing this, because now (yesterday) the German documentation
for Tag:highway=cycleway was changed to recommend always adding the
name of the parallel road to the cycleway, even regardless of the
distance. It's a big change that needs to be at least discussed,
and my attempt on the wiki to direct "the other side" to start a
discussion there, or preferably on the lists, was reverted. This is
a more fundamental question than a "what tags to use", so I've posted
this initial message on the talk list.

Either way of tagging can be made to work reasonably (at least with
additional tags), but if the names are added en masse, it requires
changes to many currently used programs for consistent and usable
results. I found very few places where the names have been added, so
the new guideline doesn't even seem to be documenting what's in use.
It's intolerable that the guideline is different for different
languages.


The reasons I have seen given for why one would tag the cycleway, too,
with the name of the road
* "routers require it for good instructions"
   (As in "turn left to cycleway X street" vs. "turn left to unnamed
    cycleway")

: IMO, that's "tagging for a router". A router/preprocessor can be made to 
check the distance to the nearest parallel road and use that name for 
directions. Yes, there isn't such code yet, but changing the software 
should be easier than changing the whole database. Even Nominatim finds 
the nearest road for housenumbers tagged only with addr:housenumber.

: If it's sufficiently difficult to code such features, why not start 
adding a (superfluous) "name_of_the_road_it's_next_to" (with a better key, 
naturally) tag that the routers/mkgmap can use?

* "All ways making up the road have the name, a cycleway on the side
is no different".

: IMO, the road has a name and the sidewalks are a separate "thing"
that happen to run along the roads. If I were to draw the curbstones
along the roads as lines, nobody would suggest that I should add the
name of the road to that curbstone way. Or the way marking a guard
rail between the cars and the pedestrians. Or the hedge along the
road, possibly between the parallel footway and the "proper" road.


The reasons I think support not adding the names to sidewalks:

* Such guideline would require a threshold distance, at which a
parallel cycleway (without any name signs) would no longer be
considered "part of the road". And what about cycleways that criss
cross that distance? To what an angle away from the road would a
cycleway need to turn before it stops being a part of the road?

* It's unnecessary data duplication. We wouldn't tag parking aisles
with the name of the amenity=parking just because they are a part
of the said named parking area.

* If/as current implementations define what's usable data, there's
two, although minor, reasons why it's not the way to tag them:

** Current rendering rules don't support the idea, and currently
they would require an additional tag to suppress rendering on such
sidewalks (say, add sidewalk=this to every such way for easier 
processing, even if that could be deduced by preprocessors and I know 
there are strong opinions against that). For an example, here's a place 
where one local mapper has been adding the names to cycleways along
roads: 
http://osm.org/go/0xPl9mW0r-?layers=B000FTF
Most of those other remaining roads will eventually get footways along 
them, too, and then those sidewalks would be named, too.
    Just imagine what city centers would be like, when all these
sidewalks had a name tag of their own: http://osm.org/go/0xPLmDUGZ-

** It confuses Nominatim: At the previous link, try searching for
Talvikkitie, and the first two resulta are a "secondary road" and
a "cycle path". For any of those roads the cycle path hit comes
up quite early in the results.

* There isn't a "cycleway with the name X Street", but "cycleway
along the road with the name X street". <- This is the fundamental
question on how to model the cycleways in question.


-- 
Alv




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