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:
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
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
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.
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?
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.)
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 Like
Mammi71
(One feature, Six mappers and still More ways to map it)
6
this is a way (track) with surface=concrete:plates
smoothness=verry_horrible!
(driven by bicycle this summer )
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 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.
In the given case I think a proposal would not be necessary as no key will be deprecated or changed in its meaning. It is more or less an improvment of the description, giving a more precise information when concrete:plates should be used.
Hm… I’ve been wanting to also start a discussion in StreetComplete again, to see how we might avoid mistagging by StreetComplete users.
But StreetComplete probably won’t change anything without evidence of clear consensus. And for example the September 2022 comment by mnalis Remove `concrete:plates` · Issue #4344 · streetcomplete/StreetComplete · GitHub stated “[if it is] 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 [then it is] surface=concrete:plates”. But that definition could make most of our cast-in-place laneways and sidewalks concrete:plates depending on the defined size of the “interruptions”. I’m not sure that’s what we should be using (if only because any larger piece of concrete in practice has interruptions).
In the first message I’ve pinged people who argued in favour of concrete:plates in the past discussions (Mateusz, Matija) but didn’t get a response other than a thumbs up from Matija. So I’m not really confident there would be consensus for this wiki change. I think I’ll start working on a proposal/request for comments so that this can be discussed very explicitly.
Resurfacing this thread ahead of creating a proposal.
Here is an example picture of a cast-in-place concrete laneway:
You can note the compression gaps, and stress cracks across two of the poured slabs. Cracks also extend from three of the four corners of the storm drain grate. A small depression has been scored into the laneway surface during construction, apparently to guide surface runoff water towards the drain grate.
Because I know it was cast-in-place, I have tagged this laneway surface=concrete.
But what features distinguish it from surface=concrete:plates such as this one?
That looks like cast in place as well, so if it’s tagged as surface=concrete:plates, that’s wrong. Anyway concrete plates are a kind of concrete, so even if they are clearly plates, surface=concrete is not wrong. Maybe the wiki should state that a surface should be tagged surface=concrete:plates only when it’s 100% sure, and that it can be tagged surface=concrete if in doubt.
This is an example of 100% sure surface=concrete:plates (a Stelcon® plate) File:N MHL 20140410 036.JPG - Wikimedia Commons
It was one of the two example pictures on the surface=concrete:plates English wiki page (now it’s one of the three example pictures)
In earlier discussions there were opinions (roughly paraphrased) “mappers aren’t construction experts so if it looks and feels like concrete:plates, it can be tagged concrete:plates”, but as discussed now, that leaves the problem of how to differentiate that tag from plain surface=concrete.
Mammi71
(One feature, Six mappers and still More ways to map it)
16
concrete:plates are recognisable to me by:
the size: larger than paving_stones, but still small enough that they don’t break when laid either by hand or with simple equipment - usually used for pavements without major loads (sidewalks, garden terraces). paving_stones tend to be somewhat smaller (max. 30 x 30 cm) and more compact, concrete:plates tend to be flat (which you only see when you lay them) and tend to be larger than 30 x 30 cm
special devices for laying: with larger concrete:plates, such as those used for ways and roads with higher loads, there are usually eyelets at the corners or ends from which they can be suspended from a crane during laying.
The steel eyelets are located in recesses and are usually no longer visible as the holes are filled - in the better version with concrete or bitumen or in the simple version with road dirt over time.
Note that in some cases there could be concrete surface cast in place with gaps/vegetation/damage at breaking joints. It is not 100% clear how to tag them.
So apparently this picture shall serve as an example for cast in place concrete which could be confused with concrete plates due to the gaps.
Concrete plates almost always have regular shapes due to using standard elements. The cuts and cracks can part a concrete area in lots of non uniform sized, non rectangular areas, like in both your pictures. It often helps to look at an intersection area
The sections are quite identical in size and have those grass filled gaps. A visitor could believe these are concrete plates, but taking a closer look reveals the irregular edges and rough surface typical for in situ concrete:
I have been wondering since the OP where those 200K surface=concrete:plates tags are related to. In reality there are not so many roads or tracks covered with concrete that could be interpreted as any kind of precast concrete plates as described in the wiki imo.
Just now I have stumbled just by chance over a footway tagged with surface=concrete:plates looking like that:
And yes, that makes sense to me. In german language we would call the concrete blocks shown in the lower right part “Pflastersteine” = “paving stones” or “Betonpflaster” = “concrete pavers”. Usually those are correctly tagged as surface=paving_stones.
The bigger concrete pavers we would call “Betonplatten” = “concrete plates” and that is the source of this tagging error I believe. If I use iD and look for surface tags in the presets I will find “Betonplatten” and KLICK, that’s it. If I don’t take the time to read the wiki I would be sure to have chosen the correct tag with Betonplatten = surface=concrete:plates.
I just had a quick look and there are hundreds of this tag right in the centers of big german cities where you will often find this kind of concrete paving plates on footwalks.
So I believe we do not just need clarification in the wiki but also a better wording in the iD preset.
)
(now it’s one of the three example pictures)
