[Tagging] Non-orthogonal crossing=* tag proposals: crossing=marked/unmarked vs crossing:markings=yes/no

[Paul Allen]

On Fri, 24 May 2019 at 20:06, <osm.tagging at thorsten.engler.id.au> wrote:

>
>
> As you said, what others suggested, and what would be a welcome addition,
> is to leave the existing tag untouched (it seems to work fine for most
> people except you), and tag the special exception where a
> crossing=traffic_signals doesn’t have road markings with
> crossing:markings=no
>

I think this is the nub of the issue: what is meant by crossing markings.
I think Nick's interpretation
is different from that of some on this list.  However, your paragraph seems
to conform to Nick's
interpretation.  What do you mean by a crossing with traffic signals AND
with road markings?

Hint: crossing=unmarked is defined as being a crossing without road
markings or traffic
lights.  Have you ever seen a crossing with lights AND zebra stripes?
Which of the two takes
precedence?  Motorists have right of way if their signal is green;
pedestrians have absolute
right of way just by stepping on the crossing irrespective of the lights.
Does not compute.

However, if you include the zig-zag lines before and after the crossing
that do NOT define
the interaction of pedestrian and motorist but impose conditions on the
motorist alone (cannot
park, cannot wait, cannot load or unload, etc) as being
crossing_markings=yes then you have
the dangerous situation that the map leads people to think that a
light-controlled crossing
(pedestrians and motorists are controlled by the lights) is a marked
crossing (like a zebra)
where pedestrians have priority.  See the problem?  But I suspect this is
Nick;s interpretation
of what a marked crossing is - there are some marks on the road (I can't
make sense of his
proposals without that interpretation).

I don't consider the zig-zag markings before or after the crossing to be
relevant to tagging the
crossing.  Any more than I consider a white line down the centre of the
road to mean that it's
a marked crossing.  Those markings do not define pedestrian/motorist
interaction.

I agree with Nick (that will surprise him) that these things matter.
Somebody with macular
degeneration may have lost all of their central vision.  It may be far
easier to spot a zebra
stripe than to see the lights on crossing signals because of relative
sizes.  In fact, you don't
even have to see the stripes, just know that they are there, because
pedestrians have priority.
That's why it's a bad idea to tag in a way that could lead somebody to
conclude that a crossing
with signals is a marked crossing.  Instead of hunting for the button and
listening for the signal,
they'll just step into the road knowing (incorrectly) that traffic will
stop for them.

Could we make the tagging more explicit?  For sure.  Could we improve the
documentation?  Yep.
Should we say that light-controlled crossings are marked?  Nope.
traffic_signals and marking
are NOT orthogonal, they are mutually exclusive alternatives.  Well, in the
UK they are - it's possible
there's some country where you can have  zebra-light-controlled crossings.

-- 
Paul
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