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

Alex Mauer hawke at hawkesnest.net
Tue Mar 4 07:24:19 GMT 2008

Karl Newman wrote:
> Okay, for trunk, how about *mainly* ramp access, with grade-level 
> crossing access to side roads permitted, but without traffic controls on 
> the highway where they meet?

Hmm, I don't think the ramp access should be a requirement.  Agreed on 
"without traffic controls on the trunk highway at intersections" though.

I can think of two highways in my area (central Wisconsin) that fall 
under this; both are state highways.

> Re: County roads as secondary, I was thinking mostly of speed limits as 
> a guideline for the classifications. There aren't a whole lot of 
> numbered county roads here in California, so I don't have much to judge 
> them by.

Around here the county roads vary widely in speed limit, anywhere from 
30 to 55 mph.  They all seem to be two-lanes (total, not per-direction), 
with fairly narrow shoulders.

> So you would place unclassified above tertiary? I haven't spent much 
> time looking at road classifications when I've been in Europe (I 
> probably would now since I've joined OSM), but that seems to go against 
> the existing guidelines.

No...I use tertiary as you describe "missing_tag":
"residential branch roads which are main roads
through subdivisions..." though, I don't see why it should be exclusive 
to residential/subdivision areas.

I noticed now there's also a difference in your usage of unclassified; 
As I use them, these are ordinary, unremarkable roads; if they were in a 
residential area, they'd be highway=residential.  So I put 
"unclassified" down a level from where you do, in between your 
missing_tag and residential.

The first part of your description of unclassified seems to fit there, 
as well: "urban commercial district or rural low-density housing..."

I suppose we differ in that I feel that tertiary can scale: in a 
residential area, it's the "main roads with fewer driveways", in a 
commercial or industrial area, it's the main roads as well, and in rural 
areas it's main roads which are not county highways.

I would not use "direct driveway access" as a factor for distinguishing 
highways.  Roads of all classifications except motorway may have direct 
driveway access, especially in rural areas.

-Alex Mauer "hawke"

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