[Tagging] automated edits seem to remove crossing=zebra drastically

Matthew Woehlke mwoehlke.floss at gmail.com
Thu Sep 17 18:10:37 UTC 2020


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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