[Talk-us] [Talk-us-newyork] Highway classification guidelines for New York State

[Jmapb]

Highway=unclassified is one of the several annoying OSM tags that does
not mean what the words mean. It doesn't mean that the classification is
nebulous, or that a decision is pending. It's for roads that connect
locations but are a tier on the road network below tertiary. And yes,
the unfortunate name "unclassified," I'm told, is derived from standard
highway nomenclature in the UK and so made it's way into OSM.

Likewise highway=residential is also one of the annoying OSM tags that
isn't to be tagged or interpreted in a literal fashion. It's used for
local public roads that don't serve the purpose of linking locations. It
doesn't matter whether these roads are alongside dwellings, factories,
offices, shops, or wilderness.

These are the tagging standards I've come to believe in. Carto and other
renderers may choose to draw unclassified and residential in the same
width and color, and routers may choose not to favor one over the other,
but these choices don't change the definitions.

I can't say exactly whose word I took on these definitions, or when or
where -- probably some combination of the wiki, the mailing list,
conversations, changeset comments, and other channels -- but I've been
under the naive impression that this was a settled question. It seems
it's not! If the nature of the low end of the highway classification
hierarchy is indeed up for debate, I'd say the NY proposal's
recommendations for anything below tertiary might be better replaced
with a simple text that recommends following standard tagging practices
and local conventions.

Jason

On 9/11/2021 8:11 PM, Eric Patrick wrote:
> Isn't UNCLASSIFIED something the Europeans or maybe just the British
> use for their designations? Does it have a higher or lower priority
> than RESIDENTIAL roads? I did some testing in Oklahoma and found that
> TERTIARY and RESIDENTIAL both equal the same. Routing doesn't prefer
> one over the other. As Brian had pointed out here, OSM-carto doesn't
> make that distinction either.
>
> On Sat, Sep 11, 2021 at 7:18 PM Brian M. Sperlongano
> <zelonewolf at gmail.com <mailto:zelonewolf at gmail.com>> wrote:
>
>     Thanks Jason, Kevin, and the NY mapping community for all the hard
>     work that's going into this!
>
>     Regarding:
>
>         There has always been a
>         highway hierarchy with unclassified at the bottom rank, and then
>         residential below that, ie, not ranked at all. Unclassified is
>         for the
>         most minor roads that link locations, residential is for
>         public roads
>         that don't. How these classifications are mapped to reality varies
>         wildly over the globe (the names themselves are nearly
>         meaningless) but
>         the suggestion that we should choose between these two
>         classifications
>         by the *type* of traffic carried -- not by the role in linking
>         locations, the amount of traffic, the distance covered, or the
>         road's
>         routing prominence -- seems like a sharp departure from
>         tagging norms.
>
>
>     We had fairly extensive, and quite inconclusive discussions about
>     whether unclassified and residential are peers, or whether
>     unclassified is "above" residential in the hierarchy.  Certainly
>     from a render perspective, openstreetmap-carto and OpenMapTiles
>     (the two I happen to be familiar with) do not make any distinction
>     between the two, rendering both of them equally.  I've heard it
>     noted that some routers do give unclassified less of a router
>     penalty than residential but more than tertiary.
>
>     In RI, I've been using unclassified for minor roads that don't
>     qualify for residential, service, or track, or tertiary.  For
>     example, a minor road to a dead-end industrial area.  The folks up
>     in Vermont have been using it as an intermediate level between
>     residential and tertiary.  I don't think there's really a right or
>     wrong answer to this question, but it didn't seem like from our
>     discussions that it's something we have a consensus or settled
>     answer on.
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