Tagging proposal - salt concentration / evaporation / graduation tower

I have not done research for this kind of buildings before but we have one quite close to here and that is why I know it is a Gradierwerk in german language. German wikipedia names it Gradierwerk as well and Leo translates that to graduation house. In english Wikipedia the name used it graduation tower, as you have already pointed out.

I believe the main reason there is no common english name for such buildings is that most of them are located in Poland and Germany, a few in France (if you have a look at the list in english Wikipedia). So maybe you just stick to the term graduation_tower which at least corresponds to Wikipedia EN.

I agree with graduation tower. I would prefer it and untill the discussion during first RFC I won’t create voting like this.

So now I want to know what other OSM users think untill the next proposal voting.

And so far graduation_tower wins with 63% but I will wait next 2 weeks for full results.

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Hello everyone!

Pons translates the German word “Gradierwerk” to graduation works or thorn house and the Oxford German Dictionary translates it to thorn-house or graduation-house. And a Scottish salt producer calls the construction mainly graduation tower but also graduation thorn tower and thorn tower.

graduation tower” seems completely confusing to me, as in my language it does not use such semantics. So I’d fall back to plain English trying to decipher it, e.g. from
from The American Heritage® Dictionary of the English Language, 5th Edition.:

noun Conferral or receipt of an academic degree or diploma marking completion of studies.
noun A ceremony at which degrees or diplomas are conferred; a commencement.
noun A division or interval, as on a graduated scale.
noun A mark indicating the boundary of such a division or interval.
noun An arrangement in or a division into stages or degrees.

where I’d guess the first or second definition.

or on Wikipedia:

So, to me it would the the tower in which diplomas are being handed out to successful students in graduation ceremony. Something like “mage tower”, but not for mages… Which is not what this seems to be about.
If it is about salt, brine or evaporation of water, let’s have a tag which has some of those words in the name.

IOW, “graduation tower” is extremely confusing because:

  • it has nothing to do with “Graduation”
  • it is (often?) not a “tower”

Thus name of “Graduation tower” breaks all kinds of assumptions. Wikipedia also says they are often called thorn house (which is how they are commonly known in some languages too I guess), which I also find quite confusing (as they are neither houses [for people to live in], nor have anything to do with thorns [spiky parts of some flowers]).

Wherease for example “salt_concentration” makes complete sense, even to someone whose langue calls them completely differently, i.e. from name it is quite clear to anyone that it is something that has something to do with “salt” to make it more “concentrated”.

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Afaik the process of refining brine is also known as “brine graduation” and from that point of view “graduation” has well something to do with brine refining. You will find this term also in Wikipedia EN (graduation tower) as well as several dictionaries (Leo, Pons and others) where the precise german term “Gradierwerk” is translated as graduation works or graduation house (see #6).

I am very much sure that a majority of people in Germany don’t know what is meant by the term “Gradierwerk”. They would probably have some vague idea about a “Verdunstungsbauwerk” but the correct term nevertheless is “Gradierwerk”. I understand it is better to tag objects with the correct term instead of using some “easy to understand description”, as we do with other objects as well. I am sure a lot of people do not know what a “heliostat” may be, but anyhow it is tagged as such and not as “solar tower mirror”.

It has to be added that this kind of object is disappearing step by step. Most of them have been closed down within the past 100 years and those still in use have become more touristic objects instead of production plants. Apparently not much more than 200 may still be operated in Europe, most of them in just 4 countries. From that point of view I do not see much reason to change the actual tagging which is “graduation_tower” for most of them. We should just leave it like that.

More information about brine graduation here.

Perhaps name it brine_graduation_tower then, as the website you linked to also names it (i.e. Brine graduation towers in Poland”)?

It would help give a hint what it is about (“brine”) and is in fact full name of the structure? That should make both sides converge to the same name. (it would work for me)

I didn’t know anything about this. Nederland does not have this kind of thing. After looking around a bit I learned a lot, and my conclusion is that these structures are graduation towers. Graduation is a concentration process, the word gradient comes to mind and I know that very well. The unusually high piling up of (thorn) bushes, I guess ‘tower’ is appropriate, even if it is not a typical tower building. Even the word house makes sense, looking at some of the sites.
I understand many are kept especially as tourist attractions and health resorts. Next time I’m in Poland I will visit one!

Probably better to stay away from 3 word tags if you can. Otherwise things can get convoluted. IMO tags aren’t supposed to be full sentences anyway. Instead I’d go with something like man_made=graduation tower + graduation_tower=brine (I assume there’s other types of graduation towers that could go under a similar tagging scheme).

man_made=graduation tower won with 50% of the vote!

Full proposal, discussion and definitions at: Proposed features/graduation tower & brine source - OpenStreetMap Wiki

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Although I do think that voting was heavily biased due to the way it was conducted… In fact, it seems that exactly the same number of people were for graduation_tower as there were against it.

I would’ve been happy with any clearer definition (be it evaporation_tower, salt_concentration_tower, brine_graduation_tower, etc.) - basically anything but just graduation_tower, and I guess I am not alone in that thinking (reading the comments here and at the wiki)…

But… some people were against the graduation tower, and some people were against evaporation_tower, brine_graduation_tower, or salt_concentration_tower. After over 3 months of discussion, I understood there is no chance that everyone will be satisfied with the choice. It is also not a matter of a global tag and it will probably be properly used only in Poland, Germany and rarely in other countries as it was before the conversation. In the end, I’ve decided to revert to the official name as the most frequently chosen and most common name on the Internet.

If you insist so, I can try another way to select a candidate: questionnaire, would you be able to approve…

  1. …graduation_tower
  • yes
  • no

0 voters

  1. …evaporation_tower
  • yes
  • no

0 voters

  1. …brine_graduation_tower
  • yes
  • no

0 voters

  1. …salt_concentration_tower
  • yes
  • no

0 voters

I like your engagement, but are you not putting too much effort into this matter …??.. :thinking:

that says it all. It should be left at that. Nevertheless I gave you another vote … :wink:

in such cases I made proposal, processed feedback and never proceeded with vote as risk of rejection was too high

and waited till tag use was high enough to document it as a de facto tag with significant use

process was still useful as RfC was able to confirm that there are no glaring fixable issues and tagging such feature/property is not hated

For example Tag:amenity=traffic_park - OpenStreetMap Wiki is slowly getting close to point when I will be able to request featuring in presets, see Proposed features/scaled down streets that may be used for traffic safety education or as a type of a playground - OpenStreetMap Wiki where I discussed various possible tag values for it (and likely none would have support high enough for proposal to pass).

Value of proposal process is in nitpicking/review/RfC phase. Voting is useful only because it forces/encourages discussion and feedback.

There is basically no value in approval itself.

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How much uses do we need to change tag status to de facto?

depends on tag: but in general I would say that fulfilling following would be good enough: (1) lack of more prominent schema and (2) 1000 items being mapped or 90% of all known items worldwide being mapped (3) multiple people using this tag.

For items applying very often or rare values of popular tags the threshold can be higher (dual_carriageway=yes is not “de facto” tag as tiny part of places is using it), but it does not apply here.

You are expecting a lot here … I am sure some of the most established tags do not get close to this figure. Imho a tag is well established already if used for some 50% of all items known as such.

Probably, but note that this 90% should never be trigger anyway in vast majority of the cases… The full relevant part of the quote is:

I.e. in majority of the cases there should be at least 1000 uses or more. I think that 90% would be maybe useful more like a fallback only when there do not exist that much instances in the whole world - as it would be not nice to say “well sorry but you have to map at least 1000 of them” when there are, say, only 100 instances existing in the whole world.

IOW, if more than 1000 instances exist in the world, you should always use "more than 1000 uses" part of the “rule”.

I got that and although this are just random figures I would agree to 1000 (+/- depending on the kind of object talked about) but if the number of objects is known to be less than 1000 or very close to that in my understanding a share of some 50% would do to rate a tag as “de facto”.

Anyhow as long as there is no guideline for that I understand these figures are just personal estimations.


“90% of all” is for catching things like capital=yes (capital of a country) where mapping 1000 of them is impossible as there is less than 1000 countries.

But anyway it is not some God-given-guidance, just some rough numbers that would be entirely sufficient for me.


I’ve added more graduation towers: from 140 to 225 uses.
:chart_with_upwards_trend: +60% :chart_with_upwards_trend:

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