[Talk-us-massachusetts] Crossings

[Greg Troxel]

"Alan & Ruth Bragg" <alan.ruth.bragg at gmail.com> writes:

> Tagging crossings is a bit confusing for me. The crossing wiki
> <http://wiki.openstreetmap.org/wiki/Key:crossing> itself is being cleaned
> up.
>
> Previously, I just extend my footway across a highway and tagged the
> intersection node as highway=crossing.

That should only be if there is actually a crosswalk.  If a footway
crosses the road, but there is no painted crosswalk, then just the node
seems right.

> Now I'm splitting the footway at either side of the road and tagging the
> section crossing the road as highway=footway, footway=crossing and
> crossing=uncontrolled,
> ​unmarked..

Do you know that most data processors are ok with this?  This seems like
it could be a classic case of people editing the wiki to make tagging
more complicated, but programs that read the data aren't dealing with
the more complicated tagging.

To me, the point of the node being highway=crossing, is that something
computing a route along the road need only examine nodes that are
members of the road's way.  By putting crossing on the footway way, one
would have to have some extended search, and that does not seem like a
good idea.

> Do I still need to tag the node with highway=crossing?

I think you need to validate the wiki text in terms of whether it is
wikifiddling about how the world might be, or describing how tags are
actually used by data processing programs.

> I've been using overpass to see what others are doing.
>
> type:way and highway=footway and footway=crossing in "MA"
> ​ (3,202 occurrences in MA​

I'm very surprised by this.  (Not saying it's wrong; just that this is
the first I've heard of footway=crossing.)

> type:node and highway=crossing  in "MA"
> ​ (​5,295 occurrences in MA)

But the real question is how many footway=crossing without having a
highway=crossing on the node that intersects the roads.

Overall, I'm guessing that having highway=crossing on the node makes the
car routers able to say "attention; crosswalk", and that the
footway=crossing is useful for pedestrian routers.
>
> The wiki page indicates you can put highway=crossing on a way.
> ​ I don't understand this.​

My view is that people writing wiki pages are often disconnected from
how progr ams that process data behave :-) I suspect this is just one of
those cases.

> I don't understand why you would tag a way like this but there are 12 ways
> tagged this way in MA.

12 is a small number compared to 3K or 5K.  Perhaps you could message
the people who did this - it seems likely an error as soeone began to be
more serious about crosswalks.

FWIW, I draw highway=footway in the crosswalk, connected to sidewalks
(or the same way, if it extends), and add highway=crossing where the
crosswalk way crosses the road way.

> Joe Holmes offered me this advice:
> ​"A common problem is sidewalks which go along a street, and the walkers
> can cross all the side streets. This is your "crossings" case. The
> sidewalks are always highway=footway. It is important that the sidewalks
> actually connect to the road to indicate that someone walking or biking on
> the road could get on the sidewalk. So I have always been making a
> connecting node. I was unaware of the highway=crossing point attribute. I
> think you should include that, to document why you are connecting different
> types of highways. I will do that in the future. Not if there is actually a
> pedestrian bridge or tunnel.

I would say that highway=crosssing is only appropriate if there is a
painted crosswalk.  The node is alawys appropriate, as Joe says, to
represent that one can turn from walking on the side road to walking on
the sidewalk.

> My reading of the use of highway=footway is that there are only three types
> of footways, as follows:
>
> 1) footway=sidewalk  -- A sidewalk along a street.
> 2) footway=crossing  -- A pedestrian crossing of a street
> 3) <no footway= tag>  -- Everything else. Examples are paved entrances into
> buildings like schools and churches, and sidewalks not along a street.

And trails in the woods, sometimes, depending on one's highway=path vs
highway=footway opinion :-)

> So when I see a sidewalk in OSM, I make sure it is marked highway=footway /
> footway=sidewalk along the street. And where it crosses a street it is cut
> and marked highway=footway / footway=crossing / crossing=xxx. However, I
> now see that my crossing values are depreciated. This is changing so fast!​"

I really have to wonder about whether footway=crossing indicates a
painted crosswalk, or just a place where a footway crosses a road.  To
me this is the key semantic confusion, at least in my head.

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