[Tagging] Formally informal sidewalks

Svavar Kjarrval svavar at kjarrval.is
Fri Jul 14 11:19:48 UTC 2017



On fös 14.júl 2017 10:51, Martin Koppenhoefer wrote:
>
>
> 2017-07-14 12:20 GMT+02:00 Svavar Kjarrval <svavar at kjarrval.is
> <mailto:svavar at kjarrval.is>>:
>
>
>     A street segment with no sidewalks on either side:
>     http://www.openstreetmap.org/#map=19/64.12876/-21.90466
>     <http://www.openstreetmap.org/#map=19/64.12876/-21.90466>
>
>
>
> This is an urban example, but probably you don't have sidewalks in
> most of the country (rural areas), and it likely isn't a problem for
> routing engines.
>
Don't know how the comment about it being an urban example contributes
to this discussion, as this is a real life case needing a solution. More
than half the population of the country lives in the capital area, from
which all the examples are located. Therefore, that area has received
the most focus of the local OSM community.
>
>  
>
>     A street with a sidewalk on either side but no marked crossings:
>     http://www.openstreetmap.org/#map=17/64.08800/-21.89846
>     <http://www.openstreetmap.org/#map=17/64.08800/-21.89846>
>     (Sidenote: If one tries to route from no. 73 to 42,
>     GraphHopper suggests a long route while Mapzen assumes the user is
>     already on the other side of the street)
>
>
>
>
> These are (IMHO) mapping errors. You can't draw isolated footway
> islands and expect a router to magically understand those are
> sidewalks which you can cross without a connection. E.g this:
> http://www.openstreetmap.org/way/102907998
> There aren't even footway subtags like footway=sidewalk, but even if
> there were I wouldn't expect working routing from this graph.
The example was provided as a mean to visualise, not an example of a
routing error (per my comment regarding it).
>
>
>  
>
>     A street segment where the paved sidewalk ends prematurely (same as I
>     described, except they do widen the street in that case):
>     http://www.openstreetmap.org/?mlat=64.11777&mlon=-21.84680#map=19/64.11777/-21.84680
>     <http://www.openstreetmap.org/?mlat=64.11777&mlon=-21.84680#map=19/64.11777/-21.84680>
>
>
>
> no immediate problem for routing, as they are connected
Same as above, provided for visualisation.
>
>  
>
>     (Sidenote: I do wonder if it would be alright to put a sidewalk
>     talk on
>     the road segment at the end of that street)
>
>
>
> the properties will always refer to the whole object, so if a part of
> the road has a sidewalk, another part has not, you have to split the
> road and add different tags.
>
> I wonder how all those tags have come into OSM, and what their meaning
> is? Has this pile of cryptic, undocumented abbreviations really made
> it through the import process?
> http://www.openstreetmap.org/way/92639788
The import process was organised by the local community. The references
are mostly in Icelandic words or abbreviations thereof. I'm not saying
it was perfect, and in retrospect, I think it would've probably been
better if they had been translated to English before the import.
>
>
>
> Routers seem to
>
>     have a hard time knowing when it's alright to suggest the user "jump"
>     onto the sidewalk from the road or vice versa if there isn't a footway
>     such as ones used for crossings. 
>
>
>
>
> you should assume that routers never "jump" from one way to the other
> without an explicit connection.
Indeed I do, and I do understand (some of) the reasoning for it. Part of
the issue is the lack of data for the router to realise that there is a
connection or make it understand that it such a "jump" would be ordinary
in certain circumstances.
>
>
> Cheers,
> Martin
>
With regards,
Svavar Kjarrval




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