On 17/09/2020 13.44, Tod Fitch wrote:
On Sep 17, 2020, at 9:30 AM, Matthew Woehlke wrote:
On 17/09/2020 10.07, Shawn K. Quinn wrote:
On 9/17/20 08:15, Matthew Woehlke wrote:
It's also atrocious because it can *only* be verified by survey. As
much as we prefer surveys, the reality is that a lot of mapping
happens just from aerials, where crossings (both marked and, in some
cases, unmarked) can be seen, but signals cannot.
I have mapped many traffic signals (and, for that matter, stop and yield
signs) based on shadows visible on the satellite photos. If you look
carefully enough (Bing and Mapbox Satellite at least), they are there.
(Local knowledge helps too in some cases.)
*Traffic* lights I can buy. I am more suspicious of the claim that
you can tell whether they have pedestrian crossing signals or not,
or that you can reliably identify other signage based solely on
outline. *Maybe* if you get lucky and have a very clear shadow at
the right angle, but if you try to tell me you can identify
https://www.openstreetmap.org/node/7695704414 (n.b. a yield sign)
from a shadow in aerial imagery, I am going to be deeply suspicious
;-).
Not from the signs or shadows of the signs, but in my area the
pavement markings can often tell you if it is a stop or yield. Some
times it is easy (“STOP” or “YIELD” painted on the pavement). But it
seems that newer road work uses a different style limit line for a
stop versus yield.
Ah, that's fair; I was under the impression we were talking about
*signs*. Possibly because most of the yields I see are to yield to other
*vehicles*, not pedestrians. (I *have* seen "yield to pedestrians", now
that I think about it, but not sure I've ever seen *lane markings* where
it's clear that what you are supposed to yield for is pedestrians. Other
than crosswalks, anyway. Which... makes me wonder if
"crossing=uncontrolled" is even correct; even more reason to not use
that! My understanding was "uncontrolled" meant by traffic signals, but
now I'm not so sure.)
I've tagged some yields based on lane markings myself, e.g.
https://www.openstreetmap.org/node/7714853074.
Back to the original topic: I am not really sure what, if any, the
US version of a “zebra" crossing is versus a “marked” crossing. So I
usually just tag as “marked” as that seems to be the more generic
item.
Likewise. Even the wiki notes that this is unclear "outside the UK" (as
I previously observed).
The crossing you linked to *might* be an example of a US “zebra”
crossing. Can anyone verify that for me. Also, there are no tags on
the intersection node itself. Should there be? I have assumed that
there should so that vehicle based navigation would have the
information needed to advise the driver of particular type of
crossing ahead.
As I understand it, yes, and I've tagged that in other places (e.g. the
above example). I actually have no idea why that node is marked as a
yield; I don't think there's actually a yield there, but I'm hesitant to
just delete it (even though apparently I'm the one that added it).
Unfortunately I can't go survey it right now. (Have to try to remember
to do that when/if I ever make it back to that Cracker Barrel :-).)
--
Matthew
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