[Talk-us] US Highway Classification (Was: directions of ways in MassGIS data)

David Lynch djlynch at gmail.com
Tue Feb 3 16:49:26 GMT 2009

What I've tended to do in my part of Texas is:

Motorway - two or more consecutive intersections with grade separation and
no driveways, or any interstate (some very rural locations do have the
occasional turn off directly from the main travel lanes)
Trunk - US highways without any other reason to classify them up or down and
high speed divided roads with relatively few crossings and an occasional
grade separation
Primary - State highways, US highways running near and parallel to a
motorway, and wide, heavily-traveled urban/suburban streets
Secondary - Other state highways (farm-to-market roads, loops, spurs) and
major city streets
Tertiary - Residential collector streets, some rural roads that are in good
condition and connect to classified highways, and service roads running
parallel to a motorway.

On Tue, Feb 3, 2009 at 09:44, Zeke Farwell <ezekielf at gmail.com> wrote:

> We need a detailed road classification chart on the US wiki page to
> straighten all of this out [?]!  Maybe I'll find the time to get working on
> that one of these days...  I think I'm also having trouble making the OSM
> road classification system do everything I want it to.
> "the consensus is that the highway tag is for making a general description
> of the *physical* attributes of a highway. This gives the user of a
> highway more useful information than a legal classification."  -  Key:
> Highway (OSM Wiki)  <http://wiki.openstreetmap.org/wiki/Key:highway>
> This is true for high zoom levels, but at low zoom levels this can be too
> much information.  When I am looking at a map of an entire state, I want to
> see what the main routes are through that state, not every important road.
> In Vermont some important 2 lane north/south routes are VT 100, VT 116, US
> 7, and VT 22A.  Physically they are pretty similar, and so by OSM standards
> they should all be primary.  In my opinion though, at low zoom levels US 7
> should stand out from the others because it connects larger towns, has a
> higher legal designation, and it stands out on other maps.
> I suppose this is really an issue for renderers, but we do need some sort
> of tagging for the renderers to use.  Maybe once route relations become more
> prevalent renderers could emphasise different higher level route networks
> more, regardless of the physical highway tag.  Any thoughts?
> Zeke Farwell
> Burlington, VT
> On Mon, Feb 2, 2009 at 10:20 PM, Greg Troxel <gdt at ir.bbn.com> wrote:
>> (replying to Zeke and Chris both)
>> I agree that if there is only 1 mile of motorway class road among
>> trunk-class road that tagging it motorway isn't useful.
>> The parts of Route 2 that I was thinking of tagging as motorway are
>> physically indistinguishable from an interstate, and at least 10 miles
>> long.  I am not 100% clear that pedestrians/bicycles are banned, but I
>> think someone would call the police if either were on the road - I never
>> see them when driving on 2.`
>> As for the trunk designation, I find that a bit ocnfusing, but my
>> impression is that it is a road that is somewhat more than a regular US
>> highway physically, but not all the way to interstate.  An example would
>> be a road with 2 lanes in each direction and jersey barriers, but
>> same-grade junctions with lights every few miles.  Rt 2 is like this
>> between 128 and Tracey's corner (1st intersection west) and really all
>> the way to South Acton where it is motorway again until about 7 miles E
>> of Orange and then it's back to trunk (1 lane each way only, but with
>> exits).  Further west it is just a primary road, but gradually being
>> made more like trunk.
>> I don't think being the only main road should qualify a way as trunk; it
>> seems being important is only enough to get a road to primary.  But some
>> degree of limited access and being divided would be enough for trunk.
>> So I'd leave rt 2 as motorway/trunk mixed.  I've driven rt 7 from
>> Bennington to Burlington, and it didn't in general feel like "almost an
>> interstate but not quite" - it felt on balance more like primary.
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David J. Lynch
djlynch at gmail.com
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