[Tagging] roads with many names

Kevin Kenny kevin.b.kenny at gmail.com
Sun Aug 18 19:47:24 UTC 2019


On Sun, Aug 18, 2019 at 12:28 PM Richard Fairhurst <richard at systemed.net> wrote:
> Rob Savoye wrote:
> > Where I live in rural Colorado, many of the roads have 3 names.
> > The county designated one like "CR 2", but often have an alternate
> > name everyone uses like "Corkscrew Gulch Road", and then many
> > have a US Forest Service designation like "FS 729.2B".
>
> name=Corkscrew Gulch Road
> ref=CR 2
> usfs:ref=FS 729.2B
>
> I think this holds even if the "county-designated name" is CR 2. The "name
> everyone uses" tallies with OSM standard practice; the official reference is
> what we have the ref tag for.

If there are overlaid refs (and even if there aren't) it's better
North American practice to create route relations for the numbered
routes. That also lets the 'ref' be associated with a 'network', so
that a more sophisticated renderer can get the shields right.  Note
that 'CR' is NOT enough information for a shield - if you look at
https://kbk.is-a-geek.net/catskills/test4.html?la=41.9474&lo=-74.9127&z=14,
you'll see that Bergen County 3/89 have a style of shield distinct
from Passaic County 677.

Simple examples of concurrencies at
https://kbk.is-a-geek.net/catskills/test4.html?la=44.2134&lo=-73.5966&z=15,
where Court Street is US 9 and NY 9N through the village, or
https://kbk.is-a-geek.net/catskills/test4.html?la=41.9474&lo=-74.9127&z=14
where I-890 is concurrent with NY 7 for a couple of exits.

Obviouisly, arbitrary combinations of network are possible, as at
https://kbk.is-a-geek.net/catskills/test4.html?la=41.9474&lo=-74.9127&z=14
where NY 206 shares its roadway with first Sullivan County 179, then
Sullivan County 91, then Delaware County 7, or
https://kbk.is-a-geek.net/catskills/test4.html?la=41.9474&lo=-74.9127&z=14,
where US 202 is concurrent with US 1A and Maine 9 on Main Street, and
then concurrent with I-395 and Maine 15 on the freeway.

It's best to avoid CR as the network in favour of a string like
US:NY:Delaware. It's a bad assumption to guess that a renderer could
deduce this from the borders of the administrative regions.  Nearly
the whole of NY 120A is in Connecticut
https://kbk.is-a-geek.net/catskills/test4.html?la=41.9474&lo=-74.9127&z=14.

Having the route available also helps sort out the directions in the
signage, as where the eastbound direction of the bridge at
https://kbk.is-a-geek.net/catskills/test4.html?la=41.9474&lo=-74.9127&z=14
is NY 30 North and NY 145 South.

The recommended network for USFS numbered routes is US:NFSR:(name of
the forest):NFH for a National Forest Highway, or US:NFSR:(name of the
forest):NFR for a National Forest Road. If the renderer that I've been
linking to in this message gets one of those (or just USFS for the
network, but the same numbers can be reused many times, so it's better
to have the forest included), it'll produce a shield that looks like
https://kbk.is-a-geek.net/attachments/20190818/nfsr2336.png.

If a road has no name other than its ref, practices differ between
putting in noname=yes, just leaving the name off, and giving it a name
like 'State Highway 9'. I tend to prefer the last of these, since a
renderer that doesn't have any fallback for ways without a name will
still at least render something. I also don't disturb 'ref=*' on the
way when I'm creating a route relation, but when doing rendering of
shaped shields, I ignore 'ref=*' entirely on ways that participate in
route relations.

If possible, (borrowing from another thread), keep the ways in a route
relation sorted. (If you or your editor can't do that, I'll cope, but
it makes matters easier for data consumers.)

These practices are seldom necessary in Europe, where route
concurrencies are rare, and pictorial markers are not important. They
are controversial for the rendering of the main map, because the
requirement is specific to a single locale, and because it is foreseen
to have an adverse impact on server operations when scaled up to
planetary size with minutely updates. I work on the issue of route
rendering off and on, but it's a hobby task so my progress is
agonizingly slow.



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