[Talk-us] Trunk

Kevin Kenny kevin.b.kenny+osm at gmail.com
Sat Oct 14 01:07:21 UTC 2017

On Fri, Oct 13, 2017 at 8:17 PM, Greg Troxel <gdt at lexort.com> wrote:
> Agreed mostly.  But I don't see primary/secondary as having anything to
> do with physical; we more or less defined that as US vs state long ago.

If you read the description on the Wiki, we defined no such thing, we
merely said it was an indication: 'primary' is "A major highway
linking large towns, in developed countries normally with 2 lanes. In
areas with worse infrastructure road quality may be far worse." and
then we say "U.S. Highways are *mostly* primary." (emphasis added).
And that's true largely because they were imported that way from
TIGER, for weal or woe.

Examples: US 6 between Port Jervis and Middletown, NY is really no
longer even primary. In that stretch it isn't the major highway
linking those towns. Interstate 84 now serves that role. US 6 is
maintained there chiefly as a detour route in case I-84 has to be
closed for some reason. I'm also not sure that I'd accord it 'primary'
farther east, between Woodbury and Bear Mountain, because it's
'hgv=no' and has a reduced speed limit in the park.

By contrast, NY 17 is a freeway. (It's signed, "Future I-86" in spots.
I'm not sure what's blocking the designation- it is I-86 farther
west.)  NY 5, on the north side of the Mohawk, is correctly labeled a
'trunk' for most of its length. (It slows down and has stoplights in
the larger towns, but is dual-carriageway with only infrequent
at-grade crossings.) NY 30 is surely at least 'primary'. It's a
bad two-lane road in a lot of places, but it goes through remote and
mountainous parts of the state and is The Big Road in virtually every
community it visits.

Ulster County Road 47 is a primary (or secondary at the very
least), two-lane (uhm, usually)
gravel (or sometimes asphalt) road. It was formerly signed
NY 42 - and there are sections of NY 42 beyond both
ends of it. But the state, some years back, decided that a
road through the mountain range there could not be maintained
to state highway standards and turned it over to the county.
The non-hard-surface sections were downgraded because
they're easier and cheaper to maintain, and with the
well-compacted surface, the road runs surprisingly fast in
summer. (In winter, it's pretty challenging - snow removal leaves
something to be desired, and there's a LOT of snow up
in the pass by Winnisook Lake.) But for the villages of Big
Indian, Oliverea, Frost Valley, Claryville, it's The Highway.

Reading the descriptions on the Wiki, they all are talking about
importance, not size. "Secondary" is defined as "A highway which is
not part of a major route, but nevertheless forming a link in the
national route network." "Trunk" is "Use highway=trunk for high
performance or high importance roads that don't meet the requirement
for motorway." This is the only one that's hedged: "In different
countries, either performance or importance is used as the defining
criterion for trunk."

By contrast, if we want to say, "how big a road is this" for
rendering, we have a collection of attributes that can inform it:
"lanes", "maxspeed", "maxweight", "hgv", single vs dual carriageway,
presence or absence of grade crossings, ...

So in an ideal world, it's less of a stretch to say that "highway=*"
is the "importance" metric (which would determine the map scale at
which the road is relevant), and the bucket of physical attributes
that I mentioned is enough to determine "size" for the symbology.  I
don't know if "maxspeed" by itself is enough for routing, or if other
information is needed there; I generally consider routing to be
Someone Else's Problem.

Nevertheless, we live in a real world in which a TIGER import did
indeed tag roads by administrative level - surely a surrogate for
neither size, nor speed, nor importance, and in which people argue
whether a dual-carriageway county road could possibly be anything
higher than 'tertiary', and tag a dual carriageway as "motorway" with
downgrades to "trunk" for barely the width of each grade crossing. I
don't know what to do to get from the world we live in to a world
where the useful attributes for selection, rendering, and routing are

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