On 4 Mar 2010, at 9:38 , McGuire, Matthew wrote: > I see three dimensions of road classification at play here. > > 1) System > 2) Function > 3) Observed Character > > System is the easy one. That is the road system(s) that that the road belongs > to especially for signage, but also for road funding channels, and > maintenance responsibility. And I agree that in practice, Census Feature > Class Codes have been used (incorrectly) to identify the system to which a > road belongs. >
exactly, we should start tagging this with an operator tag or something similar. many osm mappers don't care but road enthusiasts do. > Function describes the role a road plays in a road system and the types of > trips (volume and length) it supports based on travel demand and trip > generation. This is what the Highway Functional Classification System is > designed for. It is used by Metropolitan Planning Organizations to distribute > transportation funding. > > A road's Observed Character is what kind of road it appears to be to a person > on the road. For general purpose maps, using observed character to classify > the roads intends to match a person expectations to what they see on the > ground. Character is highly correlated with function, but is not the same. > > I think Observed Character is what OSM is trying to achieve with the highway > tag. I think this because the OSM tag descriptions for highways have photos > and describe how the road looks, and you cannot determine system or function > from a photograph. I also think it is what the Census Feature Class Code > definitions describe. > 2,3 define what a navi or routing engine should use for best/fastest route and there is a wide agreement in many countries that this is how the highway tag should be used. no hard rule defined by either one. also local and relative importance of a road plays a role. In a city a 2-3 lane road might be tertiary but out in the country a primary road may have one lane in each direction. good old discussion on this topic http://www.mail-archive.com/talk-us@openstreetmap.org/msg00594.html > I would like to see all three dimensions. > > Matt > > > > -----Original Message----- > From: David ``Smith'' [mailto:vidthe...@gmail.com] > Sent: Thursday, March 04, 2010 9:33 AM > To: McGuire, Matthew > Cc: Nathan Edgars II; talk-us@openstreetmap.org > Subject: Re: [Talk-us] proposed first principles for United States road > tagging > > On Wed, Mar 3, 2010 at 10:45 AM, McGuire, Matthew > <matt.mcgu...@metc.state.mn.us> wrote: >> The US Census Feature Class Code has descriptions of most types types of >> roads. >> This would at least tie it to an existing US standard. >> >> http://www.census.gov/geo/www/tiger/appendxe.asc >> >> This designation exists in many OSM roads tagged with TIGER:CFCC. However >> most roads could definitely use some refinement. We could strip the TIGER >> from the tag to just cfcc then refine it from there. > > The original TIGER import did in fact use CFCCs to determine highway > class. It produced values of motorway, motorway_link, primary, > secondary, and residential. We've been refining that for 3 years now. > The problem is, this comes from the Census Bureau. They really don't > care about a road's functional importance. There are CFCCs for many > other things besides roads. And the few CFCCs assigned for road > features are essentially based on whether the road is an Interstate, a > US route, or a State Route, which doesn't correlate well with a road's > functional classification. > > What's more useful is the Highway Functional Classification System. > The name sounds like what we want to do. And it's from the Federal > Highway Administration, so they actually care about roads. I've also > put forward guidelines for translating HFCS to OSM. > <http://wiki.openstreetmap.org/wiki/Talk:United_States_roads_tagging#Discussion> > (Sort of buried in a wall of text. I should probably repost those > guidelines in my userspace.) > > -- > David "Smith" > a.k.a. Vid the Kid > a.k.a. Bír'd'in > > Does this font make me look fat? > _______________________________________________ > Talk-us mailing list > Talk-us@openstreetmap.org > http://lists.openstreetmap.org/listinfo/talk-us _______________________________________________ Talk-us mailing list Talk-us@openstreetmap.org http://lists.openstreetmap.org/listinfo/talk-us
