[Tagging] "Unambiguous crossings" proposals and related questions

[Markus]

On Sun, 19 May 2019 at 18:32, <osm.tagging at thorsten.engler.id.au> wrote:
>
> Personally, I can not remember having ever seen, in my whole life, a signal controlled pedestrian crossing that does not have road markings, excluding cases where there are temporarily no road markings at all because they haven't been painted yet after the road has just been laid down or resurfaced.
>
> [...]
>
> crossing=uncontrolled and crossing=zebra have been used a combined 1.25 million times. In practical usage, they mean exactly the same thing, and they have widespread software support already. Trying to replace them with a 3rd value that still means exactly the same things is a classical case of https://xkcd.com/927/

While it may be true that there aren't any signal controlled
pedestrian crossing without road markings, the problem with
zebra/marked using the same key as traffic_signals is that mappers
(those that don't visit the place, don't have local knowledge and
likely haven't read the documentation) see a marked crossing on the
aerial imagery and tag it crossing=zebra/marked even if there are
traffic lights -- sometimes they even retag a crossing=traffic_signals
to crossing=zebra/marked. I've already corrected dozens of them, but
there are constantly new ones being wrongly added or retagged. While
crossing=unmarked/{uncontrolled|zebra|marked}/traffic_signals
theoretically may work, it doesn't in practice. I think that only
moving traffic lights and road markings to separate keys will solve
this problem.

Regards

Markus