[Talk-us] "highway" tags in the US

Karl Newman siliconfiend at gmail.com
Tue Mar 4 04:47:19 GMT 2008

On Mon, Mar 3, 2008 at 10:36 PM, Ian Dees <ian.dees at gmail.com> wrote:

> I agree. We need to map the various road classifications that already
> exist to the UK-specific vocabulary of the OSM highway tag.
> Can we come up with a list of classifications that are currently used?
> My contribution (in order):
> - Interstate (the Interstate Highway System. Roads designated with the
> red-white-blue sign.)
> - United States Highway (Roads designated with white/black crest signs.)
> - State highway (state-specific numbered highway systems)
> - County roads (highway systems maintained by the county. Not common to
> all states.)
> - Residential roads
> What OSM tags should these roads map to?

Here are my copied notes from the Highway tag usage Talk

Agreed. The criteria listed on the Wiki page promote too many highways to
"motorways". It's too hard to distinguish between them; in dense urban areas
you could end up with a lot of "motorways". It seems to me the "motorway"
tag should be reserved for interstates, with some exceptions for major US
highways. You left out "tertiary" from your descriptions. I would see
"tertiary" as an important thoroughfare road through a town--higher speeds
and less traffic controls than "unclassified". How about these guidelines,
based on speed limits and lanes:

   - motorway: Interstate, 2+ travel lanes, ramp access only, speed limit
   65 MPH+
   - trunk: US highway, 2+ travel lanes, ramp access only, speed limit
   60-70 MPH
   - primary: US highway, 1-2 travel lanes, or State highway, 2 travel
   lanes, speed limit 55-65 MPH, can have occasional stoplights/traffic
   - secondary: State highway, 1-2 travel lanes, or larger county
   highway, speed limit 45-55 MPH
   - tertiary: County highway, other unnumbered thoroughfare, speed limit
   40-50 MPH
   - unclassified: urban commercial district or rural low-density
   housing, normally no direct driveway access to housing in urban or suburban
   areas, speed limit 30-40 MPH
   - missing_tag: It seems like there needs to be another classification
   for residential branch roads which are main roads through subdivisions but
   still have direct driveway access to housing.
   - residential: urban or suburban roads primarily for providing access
   to housing, speed limit 15-25 MPH

--SiliconFiend <http://wiki.openstreetmap.org/index.php/User:SiliconFiend>19:13,
8 October 2007 (BST)

   - Further notes: In California, a "divided" road is always at least 2
   lanes in each direction of travel. I know that's not the case in all states,
   though. I changed the criteria to clarify this.
   - I think the classifications have a lot to do with expectations, too.
   To my knowledge, an interstate will always be at least 2 lanes, ramp access
   only, 65 MPH+. The same cannot be said of US highways which, in more rural
   areas, frequently pass through towns with grade crossings and are subject to
   stoplights and other traffic controls. This is another argument to restrict
   "motorway" to interstates only. State and county highways are generally
   slower than US highways (corners aren't straightened out as much) and are
   more likely to encounter traffic controls. Also, the road surface is
   generally better maintained for interstates than US highways, and US
   highways than state highways. I know that's not universally true, but you're
   more likely to encounter large potholes on state and county roads. --
14 November 2007 (UTC)


On Mon, Mar 3, 2008 at 10:23 PM, Bone Killian <vitki at bonius.com> wrote:
> > On Mon, 2008-03-03 at 19:55 -0600, Alex Mauer wrote:
> >
> >
> > > certainly a highway that meets the
> > > standards without being designated should be tagged as motorway, but
> > as
> >
> > IMHO the only thing that qualifies a road as a motorway (in the US) is
> > the big red and blue signage identifying it as part of the interstate
> > highway system.
> >
> > If we tag things based on what it looks like (subjective) instead of
> > what it *is* (objective), the map will be a big mess of different
> > colors, without any consistency.
> >
> > I think we need an 'official' one-to-one mapping of tags to real
> > road-types.  Maybe we should arrange some sort of a vote or something?
> >
> >
> > Bone
> >
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