[Tagging] Classifying roads from Trunk to Tertiary and Unclassified

Kevin ksamples at gmail.com
Tue Aug 13 18:16:18 UTC 2019

In the US I have been a proponent of using the Highway Functional
Classification as a guide when determining road classifications. I have
used it extensively in Georgia to help with road classification.


It is a national system, with each state having a say in how their roads
are classed. Take a look, I think it's a good way to a solution for the
perennial roadway class issue in the US.


On Tue, Aug 13, 2019 at 12:21 PM Kevin Kenny <kevin.b.kenny at gmail.com>

> On Tue, Aug 13, 2019 at 7:35 AM Paul Allen <pla16021 at gmail.com> wrote:
> > Hard agree.  Even though it's starting to look like I live in the only
> country
> > in the world with a national classification system that is logical and
> > internally consistent (and even we have a few rare exceptional cases). :)
> The US certainly doesn't, because of the way we practice federalism.
> All fifty states have their own classification systems, and the
> classifications have more to do with how funding is doled out than the
> actual importance or traffic volume of the road. It is more political
> than technical. (Thanks to Martijn van Exel for pointing that out in
> last night's Zoom call!)
> Back in the days when you would grab a road map at a gas station in
> the US, the map-makers used their own hierarchy which was usually
> based on the attributes, "toll charged", "grade separated", "number of
> lands" and "surface". They typically aggregated these into about half
> a dozen different renderings, and had a legend on the map explaining
> the symbology used.
> I suspect that as routers get more sophisticated, the classification
> will become progressively less important, because attributes such as
> these will be taken into account more.
> Until then, we'll we'll always have some arguments, at every level of
> the hierarchy.  Recent arguments: "Is a six-lane dual-carriageway with
> a 120 km/h speed limit a motorway if it's hgv-no?" "Is a road built to
> full motorway standards actually a motorway if its service is suburban
> rather than interurban?" "Can a surface street that parallels a
> motorway ever be a trunk, or even primary?" "Can there be tertiary
> roads in a state that doesn't have county highways?" "Is there
> actually a difference between 'residential' and 'unclassified' in
> rural areas?" "Is the last segment of a motorway actually a motorway
> when it ends at a grade crossing? (What if the grade crossing is tens
> of km from the last elevated crossing?)"
> Of such questions are edit wars made, and edit wars make the
> classification even less useful.  Out in the boonies, I've encountered
> roads where other mappers have argued to me that the classification
> ought to be "tertiary", "unclassified", "residential", "service" or
> "track" - because different attributes of the (admittedly poor) road
> were important to different mappers. (Numbered county highway; the
> principal route, at least in summer, between two villages;
> non-hard-surfaced; a low-clearance automobile would have a bad day in
> inclement weather and a road bike would have a bad time any time;
> there are at least a few homesteads along it; and the primary reason
> for travelling in that particular area at all is forestry.)
> Alas, we can't do what Google Maps does, and aggregate the private
> information of everyone carrying a cell phone to measure current
> traffic speeds. That appears to be how Google's router makes its
> decisions.
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