Yes, sorry for not being clearer. As Ian indicates, this is the *signposted cardinal direction* of a numbered road route, which does not change with the actual compass direction of the road. The guiding principle for the United States is that the odd numbered Interstates are north/south, and the even numbered Interstates are east/west. This is independent from the local compass direction. So for example, I-80 is east-west, but runs almost north-south locally (for example here: http://www.openstreetmap.org/browse/way/203317481) but the sign would still say 'I-80 East' (or West as the case may be).
So the relation between the east--west and north--south member roles is equivalent to the relation between forward--backward. Because the cardinal direction is commonly included on the road signs (see example http://www.aaroads.com/west/new_mexico010/bl-010_eb_at_i-010.jpg) this information is useful in the U.S. (and Canadian) context as a drop in replacement for the traditional forward / backward role members. Hope this clarifies somewhat! Martijn On Tue, Nov 26, 2013 at 2:57 PM, Ian Dees <ian.d...@gmail.com> wrote: > On Tue, Nov 26, 2013 at 3:51 PM, Florian Lohoff <f...@zz.de> wrote: >> >> On Tue, Nov 26, 2013 at 12:30:25PM -0700, Martijn van Exel wrote: >> > Hi all, >> > >> > I'm new to this list so please bear with me. >> > The relation editor currently only parses 'forward' and 'backward' >> > roles when considering the visual representation in the rightmost >> > column. In the United States, north/south and east/west are very >> > common as member roles for road routes, because that is how they are >> > officially signposted. >> >> I would be very careful in using this. Is this really "south" e.g. >> 180° ? Or is it more like 99° ? Or 269° ? >> >> Most streets are not strictly on the 90° raster and signposts are >> only rough directions. >> >> Addings this to OSM might make it much more difficult for Data Consumers >> to process and interpret data. > > > No, these aren't compass directions. They're the directionality of the road. > For example, this way is part of the I-94 interstate going west, but a > compass in a car driving on it would tell the viewer they were pointing > north: > > http://www.openstreetmap.org/browse/way/39372612 -- Martijn van Exel http://oegeo.wordpress.com/ http://openstreetmap.us/ _______________________________________________ Talk-us mailing list Talk-us@openstreetmap.org https://lists.openstreetmap.org/listinfo/talk-us
