[Talk-us] [josm-dev] Relation editor support for north/south and east/west similar to forward/backward

[John F. Eldredge]

Tod Fitch <Tod at 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 at 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
> 
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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 -- john at 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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