[Tagging] Is the difference between power station and sub station clear?

[Friedrich Volkmann]

On 25.01.2013 09:29, Ole Nielsen / osm wrote:
>> On 21.01.2013 01:54, François Lacombe wrote:
>>> May someone answers that question
>>
>> power=station is used for large, fenced areas where high voltage is
>> transformed to medium voltage. In German: Umspannwerk
>>
>> power=sub_station is used for smaller objects, like buildings with 2m each
>> side and a height of a few m, where medium voltage is transformed to low
>> voltage. In German: Trafohäuschen (or Trafostation)
>
> That is a misunderstanding that was unfortunately introduced in the early
> days of OSM. The creator of the 'station' tag, Bahnpirat, has admitted it
> was a mistake, see
> http://wiki.openstreetmap.org/wiki/Power_lines#RFC_-_draft. In English as
> substation is a substation never a 'station'. A 'power station' in English
> is the same as a power plant! This leads to confusion among mappers
> resulting in quite a few power plants tagged as 'stations' according to my
> experience.

According to my dictionary, Umspannwerk = transformer station and Trafohaus 
= transformer house. Looking up "transformer station", the distinction does 
not seem as clear as in German, but after all, the term "station" does not 
seem completely wrong. The tag power=station is just missing the word 
"transformer". It should probably be renamed to power=transformer_station.

The term "substation" is missing in my dictionary. To me, it seems to be a 
technical term (covering large transformer stations as well as transformer 
houses), while in common English one would rather choose the terms 
transformer station/house. Maybe some native speaker could clarify this.

It is possible to rename both tags, but this should be carefully done, with 
3 crucial criteria to be met:
1) don't lose any information => don't shuffle transformer stations 
(hitherto power=station) and transformer houses (hitherto power=sub_station) 
together
2) update existing data
3) do it in a way that everybody can adjust to it

(3) means: Make a proposal for renaming both tags, and define a date for a 
script run doing the renaming on the existing data. Leave hints in the wiki 
for some time explaining what happened.

> I have seen a lot of small 'Trafohäuschens' tagged as 'station'
> (especially in the Netherlands) so the distinction is not that clear to
> mappers.

This may be just a mistranslation like highway=bus_station  where it should 
be highway=bus_stop. English "station" = German "Bahnhof", while English 
"station" = German "Station". This is why many bus stops are tagged 
highway=bus_station in German speaking countries.

By looking at the Wiki (or using an editor with built-in translations) it 
should be clear which tag to use. There are descriptions and photos, or at 
least there should be.

> Using voltage=* to indicate the catagory of substation is much
> better.

No, because normal mappers don't know the voltage. What we call an 
Umpannwerk looks completely diferent than a transformer house. An 
Umspannwerk is much larger, is surrounded by a fence, and has lots of 
visible technical stuff (like wires with big isolators). Everybody can 
easily recognize them, but only specialists know the exact voltages.

>> No, it was rejected. It did not get enough votes.
>
> The start of voting was never properly announced on this list. Maybe that
> could explain the few votes. I only discovered the voting by accident.
> Maybe it should be revived for a new vote?

Maybe. But don't expect a huge increase in the number of votes. This is 
something very technical, and most people just don't feel qualified to judge 
on this. Including me.

>> This is a consensus among 2 persons at best. This does not legitimate you
>> to
>> make vast changes to the Wiki. There should at least be a topic in the
>> wiki
>> talk page for some months.
>
> Discussions about tagging are supposed to take place here, not on 'talk'.

I mean the talk page (= discussion page) in the Wiki, not the talk mailing list.

Ok, there has been some topic on it, but not really a discussion, and nobody 
happened to present some vision on how so solve this.

> I think you should first justify why 'station' is a correct tag (i.e. a
> substation and not a power station).

- it has been defined in the Wiki for ages
- it is heavily in use

On 25.01.2013 10:29, Janko Mihelić wrote:
> Problem with this is that you have to define the exact area that delimits a
> big from a small substation, and the exact voltage. What about stations that
> are big in area, but low in voltage? And vice-versa?

There is no need to define exact amounts, as these two kinds of objects look 
so completely different! Just make a google images search for "umspannwerk" 
and "trafohäuschen".
Or in OSM:
http://www.openstreetmap.org/browse/way/27795895
http://www.openstreetmap.org/browse/way/118639779

> Anyway, area is obvious from the polygon you have drawn, and the exact
> voltage can be written in the voltage=* tag. There is really no reason,
> except the historic one, to categorize power substations with those tags.

See above. The voltage is not obvious to normal mappers.

> P.S. In the wiki under the part about voltage=* it says: The highest voltage
> of operation within the facility.
> Wouldn't it be better to enumerate all voltages that are in use in that
> station? Something like voltage=110;35;10

I suggest asking user aliponte, he is an expert on this.

On 25.01.2013 11:11, François Lacombe wrote:
> 2013/1/25 Andreas Labres <list at lab.at>
>
>     Transformatorstationen (aka substation) look like this:
>     http://de.wikipedia.org/wiki/Transformatorenstation
>
>     Umspannwerke (aka power station) look like this:
>     http://de.wikipedia.org/wiki/Datei:Umspannwerk_01_KMJ.jpg
>
>     It's not that big a problem to distinguish.
>
> Yes it is!
>
> The second photo doesn't show a power station at all since there's no generation facility on it.

Nobody said that it's a power station. It's what is used to be tagged as 
power=station, that's the point.

> It's only a place whhttp://dict.leo.org/ende?lp=ende&lang=de&searchLoc=0&cmpType=relaxed&sectHdr=on&spellToler=&search=spezialistere power is switched and transformed, just like the first photo.
>
> So distinguishing is not only wrong but hard to establish.

Don't prentend that you don't see the difference. This is ridiculous.

On 25.01.2013 15:44, François Lacombe wrote:
> The main problem is precisely the vocabulary used.
> OSM tagging should respect current language, especillay when OSM terms refers to totally different real life elements (plant taken for substation)

It should. But compatibility is also an issue. Just look at tags like 
amenity=prison. You cannot change that by just dropping it in the Wiki.

After all, these tags are code words, similar to a programming language. 
creat() in C is missing a letter, still it's written like this after 35 years.

On 25.01.2013 20:23, Ole Nielsen wrote:
> But still I wouldn't recommend retagging without reviewing each substation individually. In some areas the distinction between large and small substations may have been tagged consistently. In my areas of interest (Denmark, Netherlands) the use of 'station' was a big mess with the tag being put on anything from small transformer buildings to big power plants.

It seems absurd to me to create workload where tagging was consistent with 
the wiki in order to keep the mess where tagging was inconsistent.

=> If you rename the tags in the Wiki, rename them in the data too, 
otherwise there will just be chaos.

-- 
Friedrich K. Volkmann       http://www.volki.at/
Adr.: Davidgasse 76-80/14/10, 1100 Wien, Austria