[Tagging] Formally informal sidewalks

Martin Koppenhoefer dieterdreist at gmail.com
Fri Jul 14 10:51:17 UTC 2017


2017-07-14 12:20 GMT+02:00 Svavar Kjarrval <svavar at kjarrval.is>:

>
> A street segment with no sidewalks on either side:
> 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.




> A street with a sidewalk on either side but no marked crossings:
> 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.




> 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
>


no immediate problem for routing, as they are connected



> (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



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.


Cheers,
Martin
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