[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

> 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:
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?

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.

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