[Tagging] power=* tag: minor_line vs. line
penegal at live.fr
Fri Oct 16 09:28:32 UTC 2015
> From: gdt at ir.bbn.com
> To: penegal at live.fr
> CC: tagging at openstreetmap.org
> Subject: Re: [Tagging] power=* tag: minor_line vs. line
> Date: Thu, 15 Oct 2015 09:12:55 -0400
> I'm coming into this late, but I think key questions are:
> transmission vs distribution: in the US, this is a big divide.
> Sometimes transmission lines are on "poles" and sometimes on
> "towers". That doesn't really matter in terms of how they work and
> are used. The point is that 115 kV or even 69 kV is distribution to
> town-based substations, not from substations to customers. Is the
> rest of the world like this?
At least here in France, transmission lines are mainly on towers and distribution lines on poles, but there are exceptions: I know at least one example of a transmission line using towers only to cross a valley and using poles elsewhere. The difference between transmission and distribution lines is visible by the number of discs, but I don't think we can expect beginners or the first mapper that comes along to know the relation between the number of discs and the usage, transmission or distribution, of the line, that needs some technical knowledge on the power networks. Here is where the current size-based minor_line/line split is very practical, although not the best possible: it gives a simple way to do the split between minor lines and lines by simply looking at them, without having much technical knowledge about power networks operations. Of course, this split doesn't reflect the distribution/transmission split, but it easily gives the real importance of the line in the landscape, which seems more important for most consumers than knowing that a line is a transmission line.
> do we expect power-line mappers to be able to tell transmission vs
> I think it's reasonable to expect mappers to tell distribution from
> transmission. Do we mean minor_line is for distribution? Or is it some
> kind of transmission?
Yes, you can expect power-line mappers to know the difference; that even seems logical, but power-line mappers aren't the only ones to map lines, whence the above answer: general mappers can't, IMHO, be expected to know about these technical details. On the contrary, experimented power-line mappers can map details, like voltage or the number of cables, in addition of the minor_line/line split, thus allowing consumers with enough knowledge to abstract this split and get a map of transmission/distribution lines. This way, the current minor_line/line split is not a major obstacle for power networks consumers, just something to be told of to correctly interpret the raw OSM data.
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