Tod Fitch <t...@fitchdesign.com> wrote: > On Tue, November 26, 2013 1:57 pm, Ian Dees 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 > > Perhaps images like these, found nearly at random on the web, will > illustrate typical motorway and highway marking in the US. > > http://farm5.staticflickr.com/4030/5145458837_d192798a62_o.jpg > http://www.interstate80.info/i80_nevada_lettsign.jpg > > Road directionality is based on the total length of the highway. > So if the interstate (motorway) is 3000km long and generally > more east/west than north/south it will have east/west markings > on it even in areas where it is going north/south or even > reversing itself for a short distance and going west/east. > > Marking the directionality in the relation would make it easier > for creating navigation instructions that match what the driver > sees on the ground (e.g. "turn left on to ramp for I-10 west"). > > Tod > > _______________________________________________ > Talk-us mailing list > Talk-us@openstreetmap.org > https://lists.openstreetmap.org/listinfo/talk-us
Adding to the confusion, you have two conflicting schemes in use in the USA. The Interstate highways are referred to as East/West/North/South according to the direction a particular side of the highway is going, so that I-40 W and I-40 E are opposing sides of a divided highway. You also have compass-point letters used to distinguish between branches of the same route. For example, US 31 runs north/south. A portion of it branches off as US 31W, which runs roughly parallel, some miles westward of US 31, and eventually merges back into it. -- John F. Eldredge -- j...@jfeldredge.com "Darkness cannot drive out darkness: only light can do that. Hate cannot drive out hate: only love can do that." Dr. Martin Luther King, Jr.
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