Remove concrete:plates

[EvanCarroll]

It just occurred to me that I've been using this wrong the whole time, and the the picture was guiding me the wrong direction. I think it's better to remove this. It can be very hard to tell for people who haven't researched this whether or not a concrete "plate" was fabricated off site, or was poured on site as a panel (and is thus just concrete). It's also impossible to know whether or not they're held together by chains on the underside, or rebar in the pour.

It's not enough to assume that "regular gaps in between" make concrete, concrete:plates and even very experienced users are getting this wrong.

See this for more information

https://help.openstreetmap.org/questions/85524/concrete-vs-concrete-plates

The fact that this kind of question exists tells me the difference is probably not worth having in SC.

[TS-R]

I think simply removing concrete:plates will also result in wrong tagging. Removing concrete:plates will lead tagging those ways as concrete.
Maybe the tagging could be validated with smoothness tagging, similar to the track grade.

[matkoniecz]

I am not convinced that

concrete poured on site with "regular gaps in between" as concrete:plates is wrong

that seems to me to be case of concrete plate being cast on-site

But overall tag documentation on wiki would benefit from significant improvements

[mnalis]

held together by chains on the underside, or [...]

I think you misunderstood that English idiom "chained together" from wiki "Heavy-duty plates chained closely together, might have tar or sand in between the connections."

What is meant is e.g. definition 2 from merriam webster:

to put or bring together so as to form a new and longer whole
"the prosecutor meticulously and brilliantly chained all the evidence together in his closing argument"

So, it is not important where the blocks themselves were produced, or using which method, or what are their foundations (as those would indeed be impossible to anyone who is not an engineer involved in that road project to even guess at!). And it certainly has nothing to do with physical chains (i.e. oval metal links chained together).

What is important when choosing OSM surface=* tag is:

• is it one monolithic piece of concrete without interruptions/breaks (resulting in smooth driving over it) which is what this picture would result in when dried - in which case it is surface=concrete, or
• is it many separate slabs of concrete with interruptions, so when you drive over it you make "thump - thump - thump" sounds each time you encounter the break between the slabs - in which case it is surface=concrete:plates

But as you note @EvanCarroll, wiki could certainly use an improvement there. Please, feel free to do so! (as it confused you, you are the best suited person to explain it in a better and more understandable way! Your help would be much appreciated!)

[EvanCarroll]

@matkoniecz then the wiki needs to be updated because the link from concrete to conrete:plates specifically calls for "pre-fabricated".

@TS-R that would NOT make it incorrect, because there seems to nothing about concrete that would exclude concrete:plates. As documented concrete:plates are merely a subset that places additional constraints on the method of construction (pre-fabricated plates linked together).

If you didn't know if it was poured on a site or not, and you didn't know if the plates were chained together or unlinked you'd tag concrete.

[EvanCarroll]

But as you note @EvanCarroll, wiki could certainly use an improvement there. Please, feel free to do so! (as it confused you, you are the best suited person to explain it in a better and more understandable way! Your help would be much appreciated!)

I'm still not the person to do so even with your explanation that "chained together" can be metaphorical because "concrete:plates" are documented as pre-fabricated, so I'm still unconvinced "thump thump" when you're driving is sufficient to tag something as a concrete:plate.

If I was going to spend effort in this I would push for concrete:plates removal, as I am here, rather than the removal of "pre-fabrication" as a qualifier. I can't see why this matters for the map, the driving experience, or even for the purpose of rendering a visual indicator.

[TS-R]

I think using concrete instead of concrete plates is wrong IMHO as it suggests in general a smooth surface without gaps where concrete:plates let the data consumer (router) expect an unsmoother surface which could be optimized by an alternate route.

@EvanCarroll You quote was not complete. The complete text from wiki: For pre-fabricated plates, please use concrete:plates or concrete:lanes if you know how the concrete is laid out and one of these tags fits.

I think the example pictures in wiki are also clear.

[mnalis]

so I'm still unconvinced "thump thump" when you're driving is sufficient

Well, that's how I've been tagging it all along. And I'm certain I'm not the only one (see the other answers on your linked https://help.openstreetmap.org/questions/85524/concrete-vs-concrete-plates). So, one would just have to accept when they see surface=concrete:plate that this is one of the possible meanings of that tag.

If you generally feel that the tag is poorly defined and/or should not be used (which seems to be the case), StreetComplete issue tracker is not a place to do it. Preferred way is to discuss it at Tagging mailing list, and also mentioning that you initiated discussion there on Discussion page of that specific tag wiki (to invite people following that tag to the discussion). After the consensus has been reached on Tagging mailing list, by all means come back here and mention it to us, so we can take appropriate steps if needed.
Also note that in OSM, once a initially poorly defined tag is used out in the wild, there is no way to put that cat back in the bag. Best one could hope for is to discuss (at length!) and then propose new&better defined tag, and hope people will start using that instead of the old tag (which would remain unclear/ambiguous forever after).

However, if you had some claim that having both concrete:plate and concrete is great idea elsewhere, but it is some specific part of SC implementation that makes it problematic (e.g. bad pictures, unclear translation, etc) that might indeed be useful in SC issue tracker.

Regarding SC itself, there are reasons why concrete:plate was added to StreetComplete after it had just concrete for some time (see #2437, #3468 and #3354 for details).

[EvanCarroll]

How does the full quote change anything?

For pre-fabricated plates, please use concrete:plates or concrete:lanes if you know how the concrete is laid out and one of these tags fits.

IE., If they're not pre-fabricated and if you do not know how the concrete is laid out you should not use use concrete:plates?

But yes, I should post to the tagging list. I'll get that done for now.

[mnalis]

But yes, I should post to the tagging list. I'll get that done for now.

Thanks, please link the discussion here (and the wiki discussion pages) when you do, so interested parties can followup!

[TS-R]

I understand your concerns. I think if they are not pre-fabricated then in almost every case concrete:plates is not correct. I think even all non pre-fabricated concrete surfaces in good condition will have no recognisable gaps while driving over it and are like an even surface. And in this case there also will be no gras, sand or something between the segments.

And correct. I anybody is unsure what the correct tagging is it's best practice to skip this quest so it could be done by any one else or discuss this issue. So thank you for bringing this up to the mailinglist. I hope this helps to make this issue more clear for the future and for any possibly necessary changes in editors.

[RubenKelevra]

I don't think we can observe on site if concrete plates are prefabricated or cast on site.

But you can observe if its one continous surface with just small indentations, to let the surface crack there. Or if there are actual gaps in between the plates and they are just placed together.

If unsure I use concrete, as concrete:plates is a "subcategory".

Not sure however if that distinction is actually that important.

Maybe we could use just "concrete" in the list. If the user sends it, we could have a popup with both options with detailed pictures of the transitions with the notice 'if unsure use concrete'.

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Just to add my point of view on what I would tag:

paving stones

concrete plates

Unsure, would use concrete

concrete plates

concrete

concrete plates

[mnalis]

For interested parties, see also:

• Discussion at tagging mailing list: https://lists.openstreetmap.org/pipermail/tagging/2022-September/065413.html

• Help site https://help.openstreetmap.org/questions/85524/concrete-vs-concreteplates

• Wiki Talk https://wiki.openstreetmap.org/wiki/Talk:Tag:surface=concrete:plates

• and Surface: Add "concrete:plates" and "concrete:lanes" as answer options #2437 for reasons why concrete:plates was added in the first place

[EvanCarroll]

@RubenKelevra your first example of concrete plates is not a concrete plate. There is no way that concrete was prefabricated off-site. That line going half-way through the concrete is a joint. It's so the concrete which was cast on site can break at pre-defined areas and be replaced modularly. https://user-images.githubusercontent.com/614929/200263613-72b40fd2-b655-42ab-9592-d438575cd349.jpg

Your last example https://user-images.githubusercontent.com/614929/200263887-98326e2a-1511-4e1e-8b94-2a8e61513d70.jpg I also don't believe to be a concrete plate, but this is subjective without on site inspection (potentially destructive inspection). I believe in this case, what you have is concrete with just a transverse contraction joint that was planned (in between the lanes). I believe all of those other cracks which look regular are an optical illusion. The slab in the front should look bigger than the slab in the back. It does not. It actually looks smaller. This means the slab in the back is actually substantially bigger. The cracks on the lane (and not between the lanes) do not look straight to me either.

But all of this goes to say concrete:plates is stupid. Concrete is concrete. It can be smooth and good if it has a good foundation regardless of if it is poured off site and pre-stressed, or on site. And the quality will always degrade over time. There are other better methods to track quality then to assume concrete:plates are garbage. And in the USA (and likely elsewhere) this tag is misused nearly 100% of the time.

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This one is 100% an unstressed concrete plate imho https://user-images.githubusercontent.com/614929/200263790-8381da9f-55ab-44ca-bb54-dd67df8281b3.png

And the question is, why is that relevant? It's fully more descriptive, imho, to say stepping stones as the surface is non-contiguous and any form of concrete should be contiguous paving.