[Tagging] Feature Proposal - crossing=marked

Paul Allen pla16021 at gmail.com
Fri May 10 23:29:56 UTC 2019


On Fri, 10 May 2019 at 23:59, Nick Bolten <nbolten at gmail.com> wrote:

> >> - A crossing might be marked on the ground
>
> > Are there traffic signals which control BOTH traffic and pedestrians?
> If so,
> > crossing=traffic_signals.   If there are JUST road markings, no
> crossing=traffic_signals.
>
> I interpret this to mean: the necessary condition for using
> crossing=traffic_signals is that there are signals controlling both traffic
> and pedestrians. If only one or the other, it is not a
> crossing=traffic_signals.
>

That's how I intended it.  If it only controls traffic then it's ordinary
traffic lights (regardless of
whether people use it as a place to cross).  If it only controls
pedestrians it's insane: "Yep,
you can cross now, don't worry about those cars because there's nothing I
can do to stop
them."


>> - A crossing might have lighted signals for pedestrians to cross
>
> > Define what you mean by lighted signals.  If you mean a Belisha Beacon
> or something else that WARNS motorists that pedestrians cross here but does
> NOT control traffic and pedestrians then it's not
> crossing=traffic_signals.  A warning light is not a traffic signal.
>
> In this case, I was thinking of a specific "walk/do not walk" lighted
> signal.
>

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.

>
> > That's crossing=traffic_signals IF it also controls pedestrians.
> Walk/Don't Walk ot Red/Green figures or whatever.  Otherwise it's just
> traffic lights.  Even if people can cross there, it's still just traffic
> lights because the crossing (by people) Isn't controlled, just the traffic
> is.  Traffic has to stop when the lights tell them, the pedestrians take
> their chances and are uncontrolled.
>
> I take this to mean that the signals do not need to be colocated in order
> to tag crossing=traffic_signals, such as in this scenario:
> https://www.colchestervt.gov/ImageRepository/Document?documentID=185.
>
> - There are markings on the ground
>

Not necessarily.  Most countries there probably is something, if only
tactile paving for the blind.

- There are pedestrian-facing signals
> - There are traffic signals at the intersection controlling traffic
>

Those are the two important bits.  Along with the fact that they are
operated by a single
controller.  No point to them if they operate independently.  The whole
idea is that they stop
traffic to let pedestrians cross and stop pedestrians to let traffic flow.

There may be a button that pedestrians can press to signal their presence.
In some countries,
in some cases, that button is a dummy.  A light comes on to tell you that
you've pressed it but it
has no influence upon the timing cycle.  The timing cycle may be controlled
by road sensors,
or by time of day, or may have a fixed duration.  Presence or absence of a
button is irrelevant.


> If we tag that as crossing=traffic_signals, have we correctly and
> consistently communicated all of that information?
>

Maybe.  People are capable of misinterpreting anything.

>
> As an aside regarding the term "controlled", the OSM wiki doesn't actually
> say any of this about whether it's traffic or pedestrians or both being
> controlled. What it actually states is that crossing=uncontrolled is
> equivalent to a marked crossing or "crosswalk". A marked crossing can have
> or lack all forms of traffic signals that we've discussed.
>

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.

> *Sigh*  Was all this about pedantry?  The same interlocked mechanism
> controls two sets of lights on the same pole, one set controls vehicular
> traffic the other set controls pedestrians.  I didn't mean that both
> pedestrians and motorists stare at exactly the same set of lights.
>
> That's not pedantry, it's the precision that we need to describe
> crossings. Are we mapping based on lights or a connected signal apparatus?
> That's an actually important question. We should be able to say that
> clearly to new mappers and embed it into mapping tools.
>

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.

Yes, you're going to have to spell out all the variants.  Like the image
you linked to where lights are
suspended from cables in the middle of the road and only face traffic, but
they're part of the same
single crossing.  Traffic-facing and pedestrian-facing lights for the same
crossing might be on
different poles.

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.  Each crossing
goes from one
sidewalk to a central refuge, you walk along the refuge a few yards then
cross the other direction
of traffic.  They usually operate independently to increase traffic flow by
not stopping lanes in
one direction just because people are crossing the lanes in the other
direction.  One crossing
or two?  I'd say either is acceptable depending upon the level of detail
the mapper is putting in:
ideally two crossings, but to get the job done quickly it's one crossing.
Same thing for
crossings at a crossroads, except it would be one or four crossings.

Incidentally, in the UK, on staggered crossings like that audible crossing
alerts are legally prohibited.
You could hear the sound of one crossing and interpret it as the alert for
the other crossing.
So audible alerts are prohibited but the box housing the signal button is
then legally required to
have a "rotating cone" (it's optional in situations where audible alerts
are legally allowed).
See
http://www.gosocial.co/pedestrian-crossings-have-a-secret-button-this-is-what-its-for/

-- 
Paul
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstreetmap.org/pipermail/tagging/attachments/20190511/e4891a2b/attachment.html>


More information about the Tagging mailing list