OpenStreetMap
I've been using the NavFree GPS navigation app on my iPhone for a few weeks now and I've noticed that it routes based on road classification. No problem, but almost all roads in OSM are weighted as residential. I propose that the contributors focus on weighting these roads when editing.
Discussion
Comment from compdude on 9 February 2011 at 17:47
Well, we always try to do this. But there's always a bunch of other issues we have to take care of as well. The reason they're all residential (well at least in the US) is because there was a TIGER import several years ago that added all the roads for the US. There's lots of inaccuracies in the data though:
a. All the roads were uploaded as residential, even though most shouldn't be marked as this type. Just use your judgement to decide whether they should be marked as a tertiary road (any 2-lane arterial with a yellow line down the middle), a secondary road (generally 4 lanes, but could also be a heavily used 2-lane road- ie state highway), a primary road (a major arterial or state/US highway), or a trunk road (a divided highway w/ at-grade intersections).
b. Another problem with the TIGER data is that it is poorly aligned to satellite imagery, thus inducing errors in routing. The act of fixing this data (aka TIGER Fixup) takes up most of our edits on OSM. See link below for more info on TIGER fixup.
The nice thing about the data is that it provides a baseline for roads in the US and saves us a lot of time going out and surveying the roads and finding out their names.
TIGER Fixup page on the wiki:
osm.wiki/TIGER_fixup
Comment from 42429 on 9 February 2011 at 18:46
Functional road classification is a good starting point for reclassification of OSM roads:
http://dbw.scdot.org/GISMapping/ViewPdfFile.aspx?Fname=pdfs/FunctionalClass/Florence_County_FC.pdf
http://dbw.scdot.org/GISMapping/ViewPdfFile.aspx?Fname=pdfs/FunctionalClass/Florence_County_FC.pdf
Comment from Stormspace9 on 9 February 2011 at 20:23
@compdude
I've been doing the reclass for the area where I work and live based on how the roads are used, rather than how the roads are built. For instance, the town I live in has mostly two lane roads that should be classified as tertiary, but they get as much traffic as a primary road. Thanks for the definitions though. I can see I'll need to make some changes. :)
Comment from compdude on 11 February 2011 at 01:12
@Stormspace9
you don't have to follow my descriptions exactly. Just go off of how much use a road gets.
Comment from Boondoggle on 12 February 2011 at 01:33
I've just finished a 1st pass over two Georgia counties, and have indicated road type as best as possible. FK270673 passed along a URL to a GADOT road classification such as the one pointed out here, and that was a good starting point.
However, there seems to be some disagreement over road classification. For instance, in rural counties a secondary road is a two-lane paved road equal to state and federal class roads. A tertiary road can also be paved, but it tends to be a step down in quality, with "tends" as the key word. County maintained dirt roads, indicated in Georgia by a County Road Number in addition to a name, is tertiary. I had a hard time with that one, as I know of a few that can just barely support two-lane traffic.
I think a bigger issue is surface type. I've noted this while editing roads.