Thanks for the full story, Lauri. I understand now why the subject seems so sensitive to some. I retain from your story, if I correctly understood it that:* the current usage of minor_line/line is the one I previously suggested: use minor_line for lines mainly on poles and line for lines mainly on towers, with a tolerance if a line occasionally uses something different;* the problem of this modelling, which bothers some, is that it leads to a fuzzy modelling from a technical, power network point of view, because it doesn't reflect the actual usage, voltage or any technical characteristics of the power line;* the current usage of minor_line/line is nevertheless retained as it is a perceptible, beginners-friendly distinction, allows easy rendering, and as other essential characteristics, as voltage, number of cables or tower/pole shapes are already managed by other tags, even if some others, as the distribution/transport distinction, isn't modelled. Am I correct? Regards.
> Date: Thu, 15 Oct 2015 13:12:02 +0300 > From: [email protected] > To: [email protected] > Subject: Re: [Tagging] power=* tag: minor_line vs. line > > David Marchal wrote: > > I saw conflicting points of view regarding the difference between these two > > ways for modelling aerial power lines: some say that it is the voltage which > > matters, others say that it's the visibility difference that matters, others > > Hi. > > To properly understand this issue, here's the history of the tags: > - originally, in 2006, there was just the page Key:power (then under the > title "Proposed features/Power Lines") with discussions specifically > agreeing that the project should use a different tag for "large" lines > "strung from latticework pylons" and other lines. At that time, nobody had > seriously thought about ever mapping the smaller ones, and it is a common > separation on all pre-OSM maps (and their source data). Being a global > project, "latticework pylons" referred to the type of construction common in > the countries where the early mappers resided, so even if other countries > used different constructions for high voltage lines, they would still be > power=tower. The original description/proposal > http://wiki.openstreetmap.org/w/index.php?title=Key:power&oldid=6410 > and after discussions agreeing: > http://wiki.openstreetmap.org/w/index.php?title=Key:power&oldid=17349#Notes > > Power=pole was suggested already in November 2006 for support structures > smaller than power=tower (in the link above) > > - in July 2007 the descriptions of power=line and power=tower were copied > to the Map_Features. Still, the assumption and the practice was that people > didn't map "smaller" power lines at all; even if the description of 'line' > only > referenced "the path of power cables", it was assumed they'd only be drawn > between power=tower nodes, i.e. only high voltage lines on "big" pylons. > http://wiki.openstreetmap.org/w/index.php?title=Map_Features&diff=39342&oldid=39308 > > - in January 2008 pages were created for > * Tag:power=tower, with the sentence still present "Should not be used for > electricity or telephone cables carried on single wooden pole." > * Tag:power=line, which still had a description referencing "way following > power cables" > * Key:power was changed to reference the template Map_features:power, > with no change in wording > - In March 2008 some had discussed on the osm talk list that minor > lines could be mapped with a different tag. > > - following my question in September 2008 on Talk:Key:power, minor_line was > suggested and others started using it, too, if they hadn't already > prior to that. > > - in January 2009 the suggestion to use minor_line for "minor lines with poles > and not towers" was added to the list template, as well as > http://wiki.openstreetmap.org/w/index.php?title=Template:Map_Features:power&diff=next&oldid=206851 > > - In July 2009 rendering minor_line was already discussed on the talk-de > mailing > list. > > - in January 2010 the values minor_line and pole were added to the > list template, > after they had proved to be used. > http://wiki.openstreetmap.org/w/index.php?title=Template:Map_Features:power&diff=401683&oldid=344715 > > In June 2011 some user(s) wrote a proposal to change everything above ground > to > 'line' and use other tags with an unlimited list of values for > describing their differences. > http://wiki.openstreetmap.org/w/index.php?title=Proposed_features/Power_transmission_refinement&oldid=652518 > After discussions and a wiki vote such a change was even rejected in > October 2013, > and the next modified proposal (Power supports refinement) for > redefining power=tower > and power=pole was turned down in May 2015. There is no method in osm to have > the mappers resurvey, reclassify and retag the old data at a whim, nor > a method to > propagate the changes in the contested meaning of tags to (even unknown) data > consumers. > > (Digging up these dates I did see a "(overground)" thrown in the > 'line' definition to > clarify, but already lost where it was originally. ) > > In summay, the tags have been used for 9 years as such: > - power=tower: high voltage towers, usually steel latticework > - power=line: overhead lines on strung on high voltage towers > - power=pole: smaller supports, usually one-legged and/or wooden > - power=minor_line: other overhead power lines that don't qualify as > power=line > Do note that even if a 'minor_line' has two bigger towers in the > middle, for example to > cross a river or similar, the line as a whole is still minor_line. The > border case of a > remote mapper using the wrong tag for a line or minor line wrongly > identified from aerial > imagery is no different from remote road classification: the local > mappers can and will > correct it later. > > > -- > alv > > _______________________________________________ > Tagging mailing list > [email protected] > https://lists.openstreetmap.org/listinfo/tagging
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