[Tagging] Feature Proposal - crossing=marked

Nick Bolten nbolten at gmail.com
Tue May 7 20:57:58 UTC 2019


Hello, fellow tagging enthusiasts! At long last, and after many discussions
on a variety of fora, I am putting this proposal forward in the hopes of
getting feedback, making any necessary revisions, and then moving to a vote.

The motivation for changing how we tag pedestrian crossings has emerged
from the collective experience of many mappers and teachers of OSM mapping
(as well as developers of editors), where this is one of the primary
challenges to coherently mapping pedestrian features: crossing=* tags have
a ton of problems in terms of orthogonality, understandability by new and
veteran mappers alike, and semantic correctness (which also impacts
consumability). One of the primary confusions is the "uncontrolled" (and
"zebra") values, which are, in effect, intended to mean that a crossing is
"marked", but do not clearly communicate this fact to mappers, leading to
all kinds of data issues and difficulties in explaining mapping to
newcomers (and therefore getting good data).

While the proposal itself goes into detail about why crossing=marked is a
good idea and other tags are a bad idea, this is the short version:
  - crossing=* values are not truly orthogonal and this needs to be
addressed. e.g., "uncontrolled", "traffic_signals", and "unmarked" are not
truly orthogonal descriptors. This proposal is part of a larger effort to
improve the values used for pedestrian crossings, but does not depend on
that effort.
  - There is fragmentation in tag usage for marked crossings between
"zebra" and "uncontrolled".
 - I believe that a significant portion of this fragmentation can be
attributed to the unconventional use of the term "uncontrolled", which is
technically incorrect, extremely jargon-y, and currently describes *two*
things whereas other values for 'crossing' describe just one.
  - crossing=marked is direct and clear about its meaning and use cases.
  - crossing=marked is already in use and supported by various editors,
including being the default in iD and an auto-filled option in JOSM.
  - crossing=marked has the potential for subtag uses, e.g. marked=zebra.
  - We can address fragmentation via machine edits and/or reviews using

The primary goal of this proposal is to create truly orthogonal,
descriptive, and intuitive tag values for markings on crossings. If related
proposals are also accepted, the only values used on crossings would be
marked/unmarked/no, with other attributes being namespaced tags
(crossing:island, crossing:signals, etc), but acceptance of this proposal
does not depend on those other proposals becoming accepted.

Please let me know any concerns you have regarding the impacts of this
proposal or semantics. I'd like to make any ambiguities clear and have the
proposal page be as thorough as possible.


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