[Tagging] Road hierarchy

Julien djakk djakk.geographie at gmail.com
Sat Aug 10 10:40:02 UTC 2019

Hello !

I've been thinking about road hierarchy in OSM for a long time.

Classifying roads should be the same all over the world ! :O

The highway tag shuffles administration grade (in England for example
or for motorways), physical characteristics / abutters (example :
residential, motorway), access, and importance (commuting and
long-distance trip). I think the highway tag should be split into
those 5 features : admin_level, abutters, access, commute_importance
and long_distance_importance (by experience, there should be 6 levels
for importance, from the cul-de-sac road to the main artery).

Importance tags could also apply to bicycle path and footways :D

Julien "djakk"

Le jeu. 8 août 2019 à 22:26, Kevin Kenny <kevin.b.kenny at gmail.com> a écrit :
> On Thu, Aug 8, 2019 at 11:12 AM Peter Elderson <pelderson at gmail.com> wrote:
> >
> > We're on the same page. The pavement and separations argument just illustrates how local authorities may make the same distinction, and try to regulate traffic and safety informally. So here, I can use this for the classification, but in the next town it would probably not work.
> We're stuck with the hierarchy, but it doesn't really work that well
> in most places other than the UK.
> In my area, there actually is a reasonable hierarchy that reflects the
> relative importance of routes:
> motorway - Interstate, US, and State highways that are dual
> carriageways with fully controlled access. (Some of the State Parkways
> fall in this category but are named and not numbered.)
> trunk - some few special cases where a multi-lane dual carriageway is
> only partially grade-separated from local traffic, or a 'super two'
> where a single-carriageway road is grade-separated from local traffic,
> with acceleration and deceleration ramps like a motorway.
> primary - my state designates most US Highways and some numbered state
> touring routes as primary
> secondary - other state touring routes, numbered and bannered.
> tertiary - state reference routes, or numbered and bannered county
> highways. State reference routes get an ´unsigned_ref=*´ since the
> only field-visible marks of the numbers is a roughly 20x20 cm sign
> showing the number and chaining. These markers have three four-digit
> rows rows and are next to impossible to read from a moving car. Many
> are collector roads that are prominently bannered, "TO NY 7", "TO US
> 20" etc.
> The lower classifications are harder. We have had many arguments about
> the boundaries, in rural areas, between 'unclassified', 'residential',
> 'service' and 'track'.  When you get into the North Woods, New York
> has some public highways that are Pretty Darned Bad - I'm pretty sure
> that I've tagged a "highway=track abandoned:highway=tertiary
> surface=compacted tracktype=grade4 smoothness=very_bad" and decided,
> "No, I'm not driving my Forester on this before scouting ahead." On
> that particular road, there were indicia that would support any of the
> five classes from 'tertiary' to 'track'.
> I've also put reference numbers for the highway system onto
> 'highway=footway' - for roads that have been washed out or destroyed
> in rock slides, where the bannering indicates a numbered route, the
> actual route is marked with 'detour' signs, but the condition is
> semi-permanent because there's never funding to rebuild the road.
> There's actually a blazed long-distance hiking trail that follows some
> of these sections, so 'footway' is appropriate, but the sections I
> have in mind are impassable to anything on wheels.
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