Hello, It's quite simple, really: the national routes are not entirely motorways. OSM defines a motorway as "typically controlled-access highways with a minimum of two lanes in each direction separated by a barrier" (from the third of your wiki links). In the South African context, if the road is classified as a dual-carriageway freeway, it gets tagged as a motorway.
The change just north of Stanger (to use as an example) is where the N2 changes from a dual-carriageway freeway to a single-carriageway freeway. It's generally (but by no means universally) accepted that single-carriageway freeway aren't motorways as the two opposing traffic flows are not divided, and the South African road tagging guidelines (http://wiki.openstreetmap.org/wiki/South_African_Tagging_Guidelines) reflects this: tag as motorway when it's a dual-carriageway freeway, tag as trunk/primary/secondary/etc. when it's not. There is a "motorroad" tag which, according to its Wiki page, "describe highways that have motorway-like access restrictions (i.e. cyclists and pedestrians banned) but that are not a motorway" -- which sounds like the perfect tag to use for single-carriageway freeways. Indeed, I've seen a few (but not all) of the South African single-carriageway freeways tagged with "highway=trunk/primary/etc" and "motorroad=yes", and I believe that the N2 between Stanger and Richard's Bay is tagged in this manner. This is, in my opinion, how we should be tagging these roads, though I believe consensus on this might be in order. Hope this helps. --K On 8 April 2014 12:06, <m...@martinb.za.net> wrote: > Hi all, > > Is there a reason that the National Routes are inconsistently tagged? They > seem to be tagged as "Motorways" near some towns/cities, and as "trunk road" > away from these centres. The change from one to the other appears entirely > arbitrary, for example the change along the N2 near Stanger (KwaDukuza) in > KZN: http://www.openstreetmap.org/edit#map=18/-29.32051/31.34650 > > Similar baffling changes are present in other places, across the country > though. These can be identified by a change of the road from blue to green > in the standard OSM layer. > > Examples of arbitrary changes that I have personal knowledge of the > associated area: > * Near Van Reenen: http://www.openstreetmap.org/#map=14/-28.4572/29.5439 > * North and west of Port Shepstone: > http://www.openstreetmap.org/#map=12/-30.6497/30.5015 > * Near Gonubie and Berlin in the East London area: > http://www.openstreetmap.org/#map=12/-32.9401/27.7645 > * North and West of Port Elizabeth: > http://www.openstreetmap.org/#map=11/-33.8539/25.4498 > > As a related issue, Durban has multiple "motorway"s within the city area. > > I can see there being area where the N2, for example, does not match the > description for a motorway, but the transitions from motorway to trunk road > are then in the wrong places, since there is no significant change in road > quality or design at the points I have highlighted. > > Any comments? > > mtb > > Relevant wiki links: > http://wiki.openstreetmap.org/wiki/Key:highway > http://wiki.openstreetmap.org/wiki/Tag:highway%3Dtrunk > http://wiki.openstreetmap.org/wiki/Tag:highway%3Dmotorway > > _______________________________________________ > Talk-ZA mailing list > Talk-ZA@openstreetmap.org > https://lists.openstreetmap.org/listinfo/talk-za _______________________________________________ Talk-ZA mailing list Talk-ZA@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-za
