Surface=concrete vs concrete:plates

General talk Tagging general discussion
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1

Hi all,

Through process of preparing my post about removing concrete:plates tags on sidewalks in Toronto I came upon unclear and somewhat conflicting tagging guidance in the wiki and would like your thoughts.

The question is about differences of Tag:surface=concrete - OpenStreetMap Wiki vs Tag:surface=concrete:plates - OpenStreetMap Wiki.

Current wiki pages, including in different languages, are inconsistent about whether it’s important that the concrete is cast in place, or prefabricated, or undetermined. Expansion/contraction joints for surface=concrete are sometimes mentioned and sometimes not.

In Toronto we have sidewalks/footways that are cast in place and look like this:

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My questions:

  • Should surface=concrete:plates be only used for plates that are identifiably tied together?
  • Should surface=concrete:plates be only used for plates that are pre-fabricated rather than cast in place?
  • Either of the previous two?
  • If neither of the previous two, how should we consistently distinguish between surface=concrete and concrete:plates?
    • The only thing that comes to my mind is that any area of concrete with visible gaps or cuts, including expansion/contraction joints, would be concrete:plates. However, this is practically any area of concrete larger than a few square metres.
Here is my summary of the wiki pages, with links to how they look at time of writing this: (long)

  • concrete, English: “forming a large surface, typically cast in place and may have predetermined breaking joints. Note that continuous concrete surface without any breaks can be also formed from pre-cast elements.”

    • Infobox description doesn’t mention cast in place: “Cement based concrete, forming a large surface.”
    • Infobox image shows it being cast/poured in place.
    • page says “For concrete not forming continuous surface use surface=concrete:plates or surface=concrete:lanes if one of these tags fits.”

  • concrete, German (my rough translations): “A large, connected surface from concrete, mostly cast in place, can have expansion joints [Dehnungsfugen]”.

    • The same text in infobox.
    • Infobox image shows it being cast/poured in place.
    • Page text says “use surface=concrete:plates oder surface=concrete:lanes for prefabricated [vorgefertigte] plates if you know how the concrete is laid and one of those tags fits”

  • concrete, Russian (Google translations): “Cement-based concrete that forms a large surface is usually poured in place and may have pre-defined fracture joints. For precast slabs, use surface=concrete:plates or surface=concrete:lanes if you know how the concrete is placed and one of these tags is appropriate.”

    • Infobox text is “Cement-based concrete that creates a large surface area”
    • Infobox image is concrete being cast in place

  • concrete, Spanish (Google translations): “Cement-based concrete, forming a large surface, typically cast in place and may have predetermined break joints.”.

    • Infobox text “Cement-based concrete, forming a large surface.”
    • page text additionally says “For precast plates, use surface=concrete:plates or surface=concrete:lanes if you know how the concrete is laid and one of these tags fits.” although the English page doesn’t mention precast.

  • concrete, Japanese (Google translations): “Cement-based concrete forming an extensive continuous surface, usually set in place and sometimes with joints. Note that precast materials can also be used to create continuous concrete surfaces without joints. For concrete that is not a continuous surface, use surface=concrete:plates or surface=concrete:lanes where applicable.”

    • Infobox text: “Cement-based concrete forming an extensive continuous surface”
    • Infobox image shows concrete being cast in place

  • concrete:plates, English: “Heavy-duty plates placed closely together. Might have tar or sand in between the connections - or other filling such as grass or soil.”

    • Text in infobox is the same
    • Picture in infobox shows plates tied together with braces along long edge.
    • “See also” link to surface=concrete describes it as “concrete forming a large surface, typically cast in place and may have predetermined breaking joints”

  • concrete:plates, German (my rough translations): “Heavy-duty concrete plates that are connected closely on the short side, can contain tar or sand between the connections”. Note the difference with short side in German text vs long side in English image.

    • Infobox text is “Heavy-duty concrete plates”
    • Infobox image is a close-up of a concrete surface with grass growing from two parallel gaps
    • Page says “Concrete areas cast in place usually have expansion joints [Dehnungsfugen]. However, these should not be tagged as plates.”

  • concrete:plates, Spanish (Google translations): no text in page. Infobox text says “Heavy duty plates chained close together on the short side, may have tar or sand between the connections.” Infobox image same as German.

  • concrete:plates, Japanese (Google translations): “Sturdy planks laid close together. The joints may be filled with tar or sand, or even grass or dirt. Note that in some cases the concrete is poured in place, but has joints; it’s not 100% clear how to tag these.”

    • Infobox text: “Sturdy boards laid close together”
    • See also says “surface=concrete - A large surface covering of concrete, typically poured in place, sometimes with pre-prepared voids.”

  • other languages do not have specific pages for these tags

There was also discussion on wiki talk pages in 2022 and 2023

I’ll ping the participants to get their input:
Talk:Tag:surface=concrete:plates - OpenStreetMap Wiki

  • in 2022 @Matija_Nalis (I think) pointed out that verifiability is a concern, and wrote that “If it walks and quacks like a duck, it is a duck. So if it looks and feels like concrete:plates, it is concrete:plates.” while @Mateusz_Konieczny commented that a picture of a typical American concrete sidewalk with visible cuts in it looks like concrete to them.
  • in 2023 @Bruno1460 asked about clarifying the definition (wording it as “change the definition”), Matija answered with process concerns, Bruno pointed out the lack of definition of difference between the two tags

I would like to suggest the following:

  • concrete to be used for concrete by default (except concrete:lanes which is about shape)
  • concrete:plates to be used sparingly, only when mapper is reasonably certain that plates are prefabricated rather than cast-in-place, or when plates are visibly tied together with braces or ties (otherwise what’s the difference from concrete?)
    • explicitly call out prefabricated and tied together as differences for concrete:plates
  • where it is not clear whether it’s concrete:plates or concrete, default to concrete

Discussion:

  • needing to be reasonably certain seems similar to difference in using asphalt vs chipseal
BTW, here's what the StreetComplete quest asking for surfaces looks like

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5 Likes
2

Those sidewalks only look like separate “plates” because the are scored for stress relief (so they will crack along the score line as opposed to at random). So, i agree with your interpretation.

3

I’m sympathetic to the verifiability concern mentioned in the wiki discussion.

In some cases it’s easy to see that concrete has been scored for stress relief, but in other cases the markings have become filled with dirt/grass. Is there an easy way to tell the difference in this situation?

4

It could be the case that for some deteriorated cast concrete surfaces it’d be hard to tell.

The English wiki also started out with “heavy duty” as the first description first diff but it’s not really clear to me where the line to “heavy duty” could be drawn - around here we have some cast-in-place concrete laneways that see occasional garbage trucks going over them… so heavier duty than that?

Honestly at this point I’d like to make concrete:plates discouraged (edited to add: unless a mapper is really confident) because I haven’t found anyone creating a clear, easily verifiable distinction from concrete.

I am aware that we can’t fix the current tagging, but creating a much clearer definition, and getting help from apps to use that definition, could help at least not add more. (I would also keep a note in the wiki that some mappers have used the concrete:plates tag for “plain” concrete, to future data users.)

Some more past discussions I found:

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5

I agree to that and to my knowledge most concrete surfaces on roads and tracks are cast in place which is cheaper and more effective than placing precast plates. The latter makes sense where very heavy loads may be expected or for the construction of temporary roads in industrial premises (like quarries) where a frequent relocation of the roads is usual.

I also agree that the wiki page should be improved with a clearer definition … :+1:

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6

this is a way (track) with surface=concrete:plates

smoothness=verry_horrible!
(driven by bicycle this summer :scream:)

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7

Semi-seriously asking: so what’s the benefit over tagging surface=concrete, smoothness=very_horrible?

Actually I see the benefit - per the examples on Key:smoothness - OpenStreetMap Wiki, this is more of a smoothness=bad for cars. I guess a key like bicycle:smoothness to separate out the concern for bicycle comfort probably wouldn’t get much adoption.

I posted a note on the wiki talk page: Talk:Tag:surface=concrete:plates - OpenStreetMap Wiki to let more people know and get more comments.

Do people think a proposal to officially change the definitions would be the best way to proceed?

8

I would give it a very_bad at most. But probably more of a bad.
With very_horrible you have to at least push the bike, if not carry it part of the time.
Sand can be horrible or very_horrible. I’ve already travelled such routes.

1 Like