[Tagging] Feature Proposal - crossing=marked

[Paul Allen]

On Sat, 11 May 2019 at 01:09, Nick Bolten <nbolten at gmail.com> wrote:

> > I would not expect to see something like that, in any of its regional
> variations (green walking person/red stationary person in much of Europe)
> without related lights controlling traffic.
>
> So, in the case of a pedestrian warning beacon, which does not control
> traffic in the cases you've mentioned, how would you tag the crossing?
> crossing=uncontrolled? Even thought it has pedestrian-facing lights *and*
> lights intended to warn traffic about pedestrians?
>

If the light is purely a warning to both traffic and pedestrians, then it's
not crossing=traffic_signals.
If it controls both traffic and pedestrians (control as in indicating
whether they should halt or
proceed) then it's crossing=traffic_signals.  Your situation of warning
lights for traffic strikes me as
bizarre and could be argued either way.  Or maybe it needs
crossing=insane_signals.


>
> There's another user in this thread who thinks the polar opposite and that
> the lights directed at traffic are irrelevant. Who is correct? What does
> the tag mean?
>

I think the clue is in the name: crossing=TRAFFIC_signals.  Also
CROSSING=traffic_signals.  And
crossing=traffic_SIGNALS.  It is a crossing for pedestrians which has
signals for the traffic.  Of
course, going by the name alone you could argue there are signals for
traffic but not for pedestrians
but that is handled as traffic lights plus crossing=uncontrolled.


> This is making me think that my other proposal should be revised so as to
> separate out pedestrian signals from street traffic signals entirely.
> Something like crossing:pedestrian_signals=yes/no/(type) and
> crossing:traffic_signals=yes/no/(type)
>

Problematic.  What would crossing:traffic_signals even mean other than
traffic lights with an
uncontrolled pedestrian crossing.

>
> > Not necessarily.  Most countries there probably is something, if only
> tactile paving for the blind.
>
> I think I miscommunicated - I'm referring to that intersection in the
> picture only, where the crossings are marked with the ladder pattern.
>

Going by what we have at present, it's traffic lights with an uncontrolled
crossing.  Uncontrolled
because nothing except common sense tells pedestrians when to cross.  There
are no lights
telling them when they can and cannot cross.  There is no crossing guard.
It's just a place
where crossing is legal (in the US it may be illegal to cross where there
are no markings; in
the UK it's legal to cross without markings) and there also happen to be
traffic lights
controlling traffic alone.

Earlier, the necessary conditions for crossing=traffic_signals were solely
> (1) signals that control pedestrians and (2) signals that control street
> traffic. But now, at this intersection, crossing=traffic_signals implies
> markings? This is a contradiction. It is simply not possible for both to be
> true. So you can see my dilemma in trying to use such a tag.
>

I don't see the markings as necessary.  They're a secondary element that
may or may not be
present depending upon jurisdiction.  At most they're a warning that there
are traffic signals
controlling a crossing, a warning for people looking down at the road who
might otherwise not
notice the lights.  When to halt or proceed is controlled by the lights,
and those would
continue to be the controlling element even if somebody maliciously removed
the road markings.

Keep in mind, all I want to describe is whether a crossing has markings and
> whether it has pedestrian signals. That seems like something just about any
> person on the street should be able to answer, but the schema makes it
> difficult to tag.
>

I'm not opposed to being able to tag a crossing as having both lights and
markings but I don't
see it as necessary (or even very useful).  There are crossings that are
only markings and there
are crossings that are controlled by lights.


>
> > I would say that both pedestrians and traffic have to be controlled.
> Controlled pedestrians and
> uncontrolled traffic is insane.  Controlled traffic and uncontrolled
> pedestrians is traffic lights.
>
> Not according to most definitions of "controlled", in terms of traffic
> lights. A stop sign is a form of traffic control. Also, someone in the
> other thread claimed that dropped curbs were a control. Someone in this
> thread says a marked crossing is a control. Nobody agrees on what a control
> is in OpenStreetMap, so how can we ever trust data for "uncontrolled"? I'd
> guess that almost nobody is using it for anything other than a delay on a
> router (car might have to stop) or some generic visualizations of feature
> density. They can't, not reliably.
>

The wiki is clear: just road markings. No lights.  No crossing guard.  Just
markings.

>
> > The pedestrian-facing lights and vehicle-facing lights don't even have
> to be on the same pole, but they should be positioned such as to control
> the pedestrians and traffic at a crossing and be operated in synchrony by
> the same controller.  Together they constitute a single crossing.
>
> I wholeheartedly disagree. A crossing is not the signals. A crossing is
> where pedestrians cross the street. A crossing can *have* signalization:
> signals are a property of a crossing. This is similar to how a crossing is
> not an island and why crossing=island was a bad idea.
>

Ummm, we're into pedantic parsing again.  Yes, it's a crossing.  A crossing
that has lights
controlling both vehicles and pedestrians.  To be marked as
crossing=traffic_signals it must
be a crossing which has lights controlling both.  Lights that may or may
not be mounted on the
same pole but which operate in synchrony.

> Oh, and you can have two independent crossings within a few yards of each
> other which handle one direction of traffic flow on a road with several
> lanes (...)
>
> As footways, I would map this as three elements: all are footway=crossing,
> the central island is crossing:island=yes, the other two are... well, I
> don't know, really. That's what I'm asking questions about. Maybe
> crossing=traffic_signals.
>

I refer you to
https://www.gov.uk/guidance/the-highway-code/using-the-road-159-to-203
rule 197 and
https://www.gov.uk/guidance/the-highway-code/rules-for-pedestrians-1-to-35
rule 28.  You may find the other rules useful.  Yes, these apply to
crossings in just one
country, but your new tags will have to be able handle them correctly (and
they may be
useful in other countries).

-- 
Paul
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