[Talk-us] US relations tagging redux (was Re: OSM American User Group Page)

Chris Lawrence lordsutch at gmail.com
Mon Feb 2 06:17:47 GMT 2009

On Sun, Feb 1, 2009 at 4:01 PM, Apollinaris Schoell <aschoell at gmail.com> wrote:
> have started to play a bit with route relations as proposed in
> http://wiki.openstreetmap.org/wiki/United_States_roads_tagging
> relations are really great especially when using JOSM.
> But without documentation what has been done already it may end in
> multiple relations created fro the same Interstate in different places.
> I propose a page like this one for Interstates and local versions for
> state highways. having links to existing relations then can be easily
> found by all users.
> http://wiki.openstreetmap.org/wiki/WikiProject_Austria/Bundesstra%C3%9Fen

The relations tagging is still a bit of a work-in-progress; you can
see some places here and there with slightly different conventions,
and no real consensus has emerged.

Open issues:

- How "network" should be used.  My draft includes a hierarchical,
globally-unique scheme that fits with the existing recommendations for
"ref" tags on ways, but for state- and county-maintained roads there
are a few ideas out there that disagree.  My argument is that we need
to disambiguate cases like US:CA (California) and CA (Canada)* or
US:GA (Georgia) and GA (Gabon) without the renderer having to figure
out "what country is the route in?" to make the right decision.  On
the other hand, a flatter scheme may be easier for new OSM editors to
deal with... As a global project I think we'd want to distinguish
between say the British and Irish (and Northern Irish, which is a
third separate network) motorway networks or the various Auto*
networks on the continent.

- How much commonality to expect with networks elsewhere in the world.
 In Europe using e.g. ref="A 10" or ref="S 55" may make more sense...
so should this be tagged network="FR" or network="IT" or a style more
similar to the hierarchical proposal (network="FR:A", network="IT:S")
even though this duplicates information?  Where's the boundary between
special-casing and universality?

- Should we use "operator" to encompass some of the "network"
information?  My gut feeling is no, because the "operator" of a
highway (e.g. who maintains the road) in the U.S. at least has little
to do with how it is signed.  For example, state departments of
transportation maintain Interstates, yet there is no real reason to
have operator=Texas and operator=Oklahoma (etc.) relations for I-35.

- Related: if we use "operator" to mean "designator" that also creates
issues.  Interstates and U.S. highways are designated by an
organization called "AASHTO", but that's not a particularly useful
thing to render.

- What "symbol" should represent (e.g. just the generic logo for the
route type, or the "complete" logo including any information from
"ref").  The routes I've tagged with a symbol have been "complete" SVG
logos from Wikimedia... but not all of these exist.**

- Potlatch doesn't know about "modifier" so keeping bannered routes
straight is a problem.  But I'm trying to keep the "ref" tag as clean
of things that aren't supposed to be rendered in the marker logo as
possible (e.g. if you draw an U.S. Highway shield, you shouldn't try
to cram "Business" inside it).

- Nothing renders the road relations yet, so it's all empty work at
present.  I'd consider hacking a bit on Mapnik to make it happen, but
that's research I need to do.

I've done the highways around Laredo (TX) using the scheme as I would
implement it and a part of Mexican Federal Route 2 (you'll have to go
out NW to find that bit - near Colombia, Nuevo Leon) that I had to
edit... start around here and work your way around:


Texas is actually one of the hairier states to deal with because there
are about 6-9 different types of state-designated highway depending on
whether you count weird one-off routes (Ranch Road 1, Beltway 8, NASA
Road 1) as true "types" or just TxDOT being cute.


* Canada doesn't have a proper system of federally-numbered routes,
but (a) that could change and (b) each U.S. and Mexican state and
Canadian province shouldn't be polluting the top-level namespace

** Also, "outline" markers are probably preferable for mapping to the
"black background" markers for many route types that are found at

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