Surface=pebblestone duplicate of surface=gravel ...?

General talk Tagging general discussion
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Continuing the discussion from Surface=fine_gravel - is it for loose gravel or duplicate of surface=compacted:

The tagging of unpaved surfaces of highway=* is quite messy, although @Mateusz_Konieczny has recently worked on a better documentation in regard of surface=gravel/fine_gravel.

A pair of surface values which are mere duplicates in my understanding are surface=pebblestones vs. surface=gravel.

Both terms describe the same material, natural rounded stones of a size in between 2 and some 80 mm (or more). Sample pics:

Pebble(stones)

Gravel:

Any difference to be seen?

The difference is described on different website, for instance here as:

Gravel is more or less just like pebbles. Many people find it hard to differentiate between the two. The difference is pebbles are more attractive, well rounded, polished and with good colours whereas gravel is rather dull and irregular in shape.

As this difference is surely not relevant for road or track surfaces imho surface=pebblestones is just a duplicate to surface=gravel. Attractivity of the stones (which is not a fact but just an opinion) used for a surface construction cannot be a criterion to make a difference in the surface tag imho.

Therefore I would support to deprecate the tag surface=pebblestones in favour of surface=gravel.

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The title of second image is misleading.

Pebblestone and gravel are two types of surfaces that are commonly used in landscaping, construction, and road building. The main difference between the two is the size and composition of the individual rocks or stones used in each surface.

Pebblestone surfaces are typically composed of rocks that are larger than 2.5 cm (1 inch) in diameter and are smooth and rounded in shape. These rocks are often naturally occurring and are selected for their unique color and texture. They are used to create walkways, garden paths, and other decorative outdoor surfaces.

Gravel, on the other hand, is typically composed of smaller rocks, often less than 2.5 cm in diameter, that are angular in shape. Gravel is often crushed from larger rocks or stones and is commonly used for driveways, parking lots, and as a base material for construction projects.

In summary, pebblestone surfaces are characterized by their larger size, smooth texture, and decorative appearance, while gravel surfaces are characterized by their smaller size, angular shape, and functional use.

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pebblestones are always rounded?

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Surface tags not only get applied to traffic infrastructure. You have thought about this? Sure, you posted pictures of beaches.

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I would be interested in the sources where to find these information. To my knowledge the only real difference in between pebbles and gravel is the difference in attractivity, as described by the source I quoted above.

Also Wikipedia does not make this difference. On the pages for gravel and pebble it is said,

Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes. … Gravel is deposited as gravel blankets or bars in stream channels … in near-shore marine settings, where the gravel is supplied by streams or erosion along the coast … and in the deltas of swift-flowing streams.

As such natural gravel is rounded material and not sharp edged as crushed stone. The size range is from 2-64mm. If you visit a gravel pit close to a river you can easily confirm that.

A pebble is a clast of rock with a particle size of 4–64 mm (0.16–2.52 in) based on the Udden-Wentworth scale of sedimentology.

I am aware the nice rounded pebbles are used for decorative purposes in parks or gardens, but used as material for road or track surfaces they don’t do any other job than gravel, and that is what the topic here is about.

The pictures in the key:surface wiki page for surface=pebblestone do not show decorative colourful pebble surfaces but simply gravel surfaces with a particle mixture of different sizes and I am very much sure that applies for by far most of all road/track surfaces tagged as “pebblestone”.

Again the description to surface=pebblestone says

Like gravel pebbles can be used as a building part of compacted.

which is some kind of nonsense imho. In 30 years in construction business I have seen all kinds of road surfaces but never anyone trying to create a surface of compacted pebble mixture. The more nice and round and smooth a material is, the worse is the ability for compaction. Even the more irregular (but still rounded) shape of natural gravel will not give a really good hard and solid surface when compacted which is the reason why compacted surfaces normally are made by using a mixture of crushed stone (like 0-32mm) which is also called gravel in common language anyhow.

From my own experience and from different sources in the internet I’d say there is no difference in using natural gravel and pebblestone for road/track surfaces and having 2 values for these is just misleading. As is said in the link posted above: Gravel is more or less just like pebbles. Many people find it hard to differentiate between the two.

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That is perfectly fine with me.

The reason why I started this topic is that in my 30 years in construction (mostly in english speaking countries) I have never ever heard someone talk about a road or track having a “pebblestone surface”, and that is why I was wondering about this tag. If people like to use it in OSM that is fine, no wahalla. I am not demanding anything here, just to find out the thoughts of other mappers in regard of this issue.

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Just guessing, but maybe because most of them are not using pebblestone for a surface? Especially if your construction business is oriented for vehicle traffic, it is very likely that majority of them will not be using surface=pebblestone, e.g. this (click to zoom):

In that was the case case, it would maybe be far more likely that you’re more used to using something like this:

or this:

instead of pebbles. However, if your specific area of construction expertise was for example creating garden paths, those pebblestones from the first picture would likely be quite common, while (hopefully) for example surface=asphalt would be almost unheard of. That does not mean that surface=pebblestone (or surface=asphalt) do not exist; but simply that they are used for different purposes in different cases.

And that is just in one country! Now imagine the different parts of the world - do you think they would use same road constructions methods in the middle of New York City, as they do in the rural parts of Africa? I have no expertise in either, but would be truly shocked if they are having much in common.

This is likely the root of the problem, as noted in the other thread: Unless you are proposing the new tag and you want to make it as clear as possible, you should not be lookuping other sources of data on the internet besides wiki.osm.org. Only web page relevant for OSM for existing tag surface=pebblestone is surface=pebblestone OSM wiki page. Anything else will just bring confusion (e.g. lookup on Wikipedia what “Highway” is, and then try to make sense of highway=path OSM tag; not to mention highway=bus_stop and others. They would make no sense at all!)

Gravel is more or less just like pebbles. Many people find it hard to differentiate between the two.

Look at two pictures below: I (and I suspect very many people) can trivially distinguish material in the first picture from the material in the second one. Can’t you? Imagine laying on the beach, would you really not care whether the surface of the beach were looking like this:

1280Ă—852 262 KB

or like this:

1280Ă—853 568 KB

Or, imagine having to drive a bicycle downhill with motorized counterflow traffic on a rainy day, would it be all the same to you which of them is the surface? (if you don’t ride bicycle, let me help you: I ride them, and I would care a lot)

I hope that clears it up why surface=pebblestone is not a duplicate of surface=gravel ?

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:+1: Thanks mate, for your detailed answer and the effort you put into that one. I really appreciate that.

Nevertheless you did not really get my point.

Many tracks and trails I have seen have had a surface of such stone but the material was usually called gravel and not pebblestones whish is very much the same as per the definitions given earlier.

Hmm, we can well have a different understanding of gravel and pebbles but that does not mean I am dumb enough to believe the world is ending behind the outskirts of my village. I am very much aware about the different parts of the worl, have been working in many of them …

Cmon, you don’t mean that. The wiki is definitely not the source of ultimate knowledge and truth. So many unclear descriptions, translation errors, duplicate tags and the like. This forum is the place to discuss wiki isssues and I am not putting a key into question but a value which is some kind of difference.

Yes, simple. The first pic shows a portion of gravel also sometimes called pebbles. As these ones are not colorfull, shiny and otherwise attractive but simply dull and grey as you can find them in any gravel pit I’d say it’s gravel. I have never seen a downhill bike trail covered with such gravel btw.

The second pic shows a portion of crushed stone, commonly called gravel as well.

As I said: I am not demanding anything, just asking for other opinions like yours.

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I’m glad about the former :+1: , and hope we’ll be able to work on the latter, and at least come to understand what the other is trying to say (if not agree on it).

I think I’ve got your point, but I could be wrong. Let us doublecheck then: as I understood you, you seem to think that common usage in everyday speech, or in the specific industry, or at various websites like Wikipedia trumps what is written in tag description on wiki.osm.org. Is that correct summary?

If so, I disagree. How some tag key=value pair is (supposed to be) used in OSM, is defined on wiki.osm.org.

The key and value sometimes might follow (often British) English language, it sometimes might follow specific industrial lingo, or it sometimes might follow common speech in some specific country. But also, often the tag is “invented” and documented by someone whose native language is not English, and/or who does not work in the industry, and/or whose common use of the term differs drastically from the common use in the rest of the world.

They, however, have documented that tag with descriptions and pictures to the best of their ability on wiki.osm.org – and that, in my opinion, is what that specific tag means in OSM. That is what the next user that wants to map it will see on the wiki.osm.org, and if they think that description fits, that is the tag they will use. The point is not to make largest British-English-speaking map. The point to make the best map of the World, usable by whole World. For that, we all need to agree to the meaning of the tags, no matter what language we happen to speak natively. That is what description of tags is for on wiki.osm.org.

Now, that does not mean that wiki.osm.org (as you nicely put it) is the “source of ultimate knowledge and truth”. It most definitely isn’t that. Neither is it Definitive dictionary of British English (quite the contrary). It is, however, source of what that some specific key=value pair means in OSM (and nowhere else).

Sure, sometimes that definition (as you also note) could be simple, precise and clear (like I happen to think that surface=pebblestone is). Or it may (especially when people decide to forego “boring” Proposal process) be unclear, vague, and overreaching (like surface=gravel is, which it even warns about: “This tag has very large meaning range” and later details in Tag history section).

Now, what I would like you to do is an though experiment, if you will. (click to expand)

Imagine that you don’t speak a word of English (like the majority of the world doesn’t). Even better, imagine that the key=value OSM pairs are in some totally incomprehensible format to you - you know it is unique and can copy/paste it, but do not understand it at all. So instead of surface=pebblestone it says foobar=Q3311731. Then you use your computer to fetch you the meaning of foobar=Q3311731 from wiki.osm.org, and it says to you that is used for:

“Pebbles are stones rounded by waves or river flow. Typical size range from 2 to 8 cm. Describing a surface in OSM they are loosely arranged. Like gravel pebbles can be used as a building part of compacted.”

You decide that explains your situation clearly, and so you decide to add tag foobar=Q3311731 to your highway=track OSM way. That is how OSM tags work tehnically, and this is how (in my opinion) they should be used. That is the way how multiple contributors may agree they are talking about the same thing.

If you, however, decide not to read nor heed wiki.osm.org tag description, but instead decide for yourself “Sure I know what pebblestone is, I’ve been doing them for 30 years, I need not read no stinkin’ wiki – those are 1mm wide rocks which are always rose in color with no other distinguishable characteristic” (just a vivid example :smiling_face:, no offense meant, please) then the next user perhaps from another country which comes will say “I know what surface=pebblestone means in my country, I don’t need to read the wiki OSM tag definition, pebbles are 10+cm big pieces of broken green beer-bottle glass rounded by the sea”.

Now, each you might be perfectly correct where you live. And there be millions of each of you. But since you all decided to ignore what that tag actually defined it means in OSM, you will not have common ground, and will disagree about the meaning of the tag. The end result would be that surface=pebblestone would become useless worldwide - it would simply become synonym for surface=unpaved, as no better common definition could be found, each side citing their own dictionaries, their own industry, and their own common usages in their country.

If you’ve went through the experiment above, you’d see that you’re questioning the wrong value. surface=pebblestone is very clearly defined. That fact that in your experience the pebblestones are in more vivid colors is irrelevant to the wiki definition (and thus, what surface=pebblestone means in the OSM).

Sure, I agree with you there are wiki pages with issues like unclear definitions, which should be discussed, and subsequently documented as best as possible (even if it just means pointing out all the unclear and different definitions). One of such sad tags is surface=gravel. You may be sure that you know what it means without looking up the wiki, and I may be sure I know what it means without looking up the wiki. What is mostly likely result is however that we’d both be wrong.

Sometimes, when many people have been mapping for long time what they assumed without ACTUALLY reading the wiki, result is the tag that has very very wide meaning, which is bad (for hopefully obvious reasons). That is what I’m afraid has happened to for example surface=gravel by now. It seems to have been mapped for anything from surface=compacted+smoothness=good, via surface=pebblestone via surface=fine_gravel+smoothness=bad to surface=concrete+smoothness=very_horrible. So, if you find that tag on the map the best you can guess it means is likely some type of surface=unpaved which is not surface=dirt/grass. That is pretty vague (and thus bad for tag whose purpose is to make something more precisely defined).

If you however find it in real life, what you can do is replace it with better defined tags (like e.g. surface=pebblestone or surface=compacted).

TL;DR:

as these ones are not colorfull, shiny and otherwise attractive but simply dull and grey as you can find them in any gravel pit I’d say it’s gravel

And this is the core of the problem, IMHO. You assumed (from your real-world experience) that something needs to be shiny and colorful to be be called “pebblestone”, and since those rocks in picture are grey, that they are thus not surface=pebblestone. Yet, had you actually read surface=pebblestone OSM wiki, you’d see that those should in fact be tagged as surface=pebblestone in OSM, and that shineyness and color have absolutely nothing to do with that tag.

In other words, OSM definition of surface=pebblestone key-value pair is quite different from your construction-worker-definition of Pebblestone surface. People should learn to use correct definition in correct situation, and not intermix them at random.

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Man, you must have been working the whole night on that one … although my position has not changed I have to give you a :+1: for the effort to explain your point of view.

I would not make any sense to bring forward more arguments to explain my own point. We can continue like that for days and at some stage it becomes just a waste of time.

The descriptions for the different types of unpaved surfaces in the wiki are not very precise and misleading here and there. @Mateusz_Konieczny startet the topic about surface=fine_gravel because of that, trying to improve definitions in the wiki. I believe he was right and I supported that issue.

Similarly I feel the definition of surface=pebblestones misleading and started a topic for it, explaining why. And for sure my argument was not that I

so that comment would be worth a thumbs_down.

I am aware that the wiki is the place where the valid definitions for the use in OSM are documented or at least should be. If the documentation is poor or misleading it is well worth to discuss about it. And although OSM has it’s own definitions it is helpful if these are as close as possible to the definitions used in real life. That is my opinion and that is the issue of this topic, nothing else.

In view of the surface tags, my own experience is that most of the compacted forest roads in my area (and those are many) are usually tagged with surface=gravel (or sometimes fine_gravel). Why? People see the surface, look into the tagging suggestions of the editor and see “gravel” which they know from real life. Klick … that’s it. Many of them do not take the time to read the wiki apparently.

I am quite sure, similar mistakes occur with the use of the tags “gravel” and “pebblestones”. People see the surface, check the proposal list of the editor and may recognize either gravel or pebblestone, depending on what is more common to them (and many would not be able to distinguish between both in real life). Klick … that’s it.

At the end of the day the result will be that no one knows which surface is described by the tag in reality. That is why I started this topic. If other mappers feel the same, we can discuss how to improve the definitions. If not, it’s fine with me as I have made clear already.

BTW: I would not see a problem with surface=pebblestone if it would be used in a way described as

but that would require a precise definition in the wiki of course.

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Perhaps I misunderstood, but you did say:

From that I inferred that you find “colorful/shiny/attractive” as opposed to “dull/gray” as an important (maybe even primary?) distinguishing characteristics between “pebblestone” and “gravel”. I apologize if you found it as offensive (or combative or something) - that was certainly not my intention.

So, just to be clear, would you (or would you not), agree that “gray,dull and otherwise unattractive rounded rocks are more specifically called pebblestones (even if you consider them as gravel in wider sense, or rocks in even wider sense)” ?

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Actually, that was exactly my point too all the time, so it seems we do agree on main subject at least? So, if our ideas are understood, let’s work on some actionable ideas. Here is my suggestion:

  • update surface=pebblestone wiki to say “Please whenever possible, prefer this more specific tag instead of using more generic/fuzzy tag like surface=gravel or surface=unpaved if all of the surface is made of such rounded rocks”
  • update surface=pebblestone wiki to clarify that “Attractiveness of the stones is themselves is not important for using this tag; it applies equally to grey and dull stones as well as colorful and shiny ones. Important characteristic is that pebblestones don’t have sharp edges, i.e. they are never crushed stone”
  • (relatedly) wait for update of surface=gravel from other thread to mark it as very generic and suggest better (more specific) alternatives (like surface=compacted, surface=pebblestone, etc.) to reduce (as you correctly noted) problem that “no one knows which surface is described by the tag in reality”)

Do those sound reasonable to you? Do you have some additional concrete/actionable update for the wiki that you’d like to suggest?

BTW as you, I also support that @mcliquid extended definition of pebblestone (which I liked earlier) as a nice addition/change for the wiki. Is there anyone who oppose that clarification?

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I’ll reply to both of your post asap - too busy at the moment. Just to make sure you wouldn’t understand my missing reply as impoliteness.

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@Matija_Nalis … here we go with another try.

  1. Generally people use terms which are common to them, in real life as well as in OSM. Not every mapper is willing to spend time to study the wiki (*). If the presets of the editors show a term which is commonly well known, many mappers will use it without crosschecking the value in the wiki. That means: the more values which are hard to distinguish for one key are available, the more tagging mistakes will happen.
(*)

In fact, when in another topic months ago I talked about the time one has to spend to read the wiki I got the reply from another experienced mapper: The editors are very supportive for newcomers, so hardly anyone needs to read the wiki or the forum.

  1. The surface key has several values which are difficult to distinguish for someone not being an expert, specially when you look at surface values for roads and tracks. To name some of them: compacted <=> gravel, gravel <=> fine_gravel, gravel <=> pebblestone, ground <=> dirt <=> earth. One can try to add OSM specific definition to one of these values to make it better distinguishable, but that does not help when commonly known values are used without reading the specific definition in the wiki.

  2. Gravel and pebbles is very much the same in common language. The only difference one can find in various documentations is that pebbles are to be understood as better rounded and more attractive. That means for the use as surface tag pebbles would make sense if used for their attractivity as decorative element, not as surface material for a track or road.

  3. Tagging suggestions should be as simple as possible to avoid mistakes (KISS).

That is why I would support a reduction of values for gravel-based surfaces and additionally to improve descriptions in the wiki for those:

compacted = a mixture of gravel, sand and dust, compacted by vibrator or roller, resulting in a dense and firm surface you cannot brush aside by hand, with none or few loose gravel scattered on top. Best sort of ways below paving with asphalt, concrete, paving stones. Also known as water-bound macadam. Easy and smooth bike ride. Note: compacted roads and tracks are commonly often called “gravel road” and often mistakenly tagged as surface=gravel, because gravel is the most visible component of the material mixture.

gravel = a surface more or less completey created by or covered with loose gravel of different size from 2 up to some 80 mm, either intentionally build like that (cheaper than compacted) or emerged out of deterioration of a former compacted surface due to missing service. Rough and shaking bike ride. Gravel can be naturally rounded material (natural gravel) or sharp edged (crushed stone). For more detailed tagging, use the appropriate subtags.

fine gravel = a surface completely covered with fine gravel of sizes in between 2 and 8 mm. Fine gravel can be naturally rounded material (natural gravel) or sharp edged (crushed stone). For more detailed tagging, use the appropriate subtags. If there is just a thin gravel layer on a hard surface it will provide a reasonable bike ride, thick layers may be difficult to ride by bike due to “sinking in”.

These values would allow a simple basic tagging for all surfaces on the base of gravel/crushed stone which is here understood as:

Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes; it is also produced in large quantities commercially as crushed stone.

(following the most common definition of gravel, quoted from wikipedia), in other words:

  • Natural gravel is round edged due to the erosive processes and produced by simply screening the material in gravel pits.
  • Crushed stone is sharp edged and produced by blasting/crushing material in quarries.

In most cases it would not be necessary to distinguish between natural gravel and crushed stone. The smaller the particles, the more neglectable is the difference.

In case a mapper wants to provide a more detailed tagging (knowing more details or having read the wiki) a set of subtags would do better then more primary tags (like surface=pebblestone):

  • gravel=natural_gravel (if it is definitely rounded material)
  • gravel=lag_gravel or cobblestone (if it is rounded material with sizes bigger then some 60 mm)
  • gravel=crushed_rock (if it is definitely sharp edged material)
  • gravel=riprap (if it is sharp edged material with sizes bigger then some 60 mm)

Note that riprap does not specify a size range of the stones, it is used for very rough material generally. In the wiki the term “track ballast” is mentioned for rough size crushed rock. This material also does not have a general size specification but normally does not exceed 60 mm.

For the use of lag_gravel/cobblestone as well as riprap/track_ballast one has to say that there may be very few roads or tracks worldwide built by using natural gravel or crushed rock in particle sizes exceeding 60 mm. Therefore it could be helpful not to use specific terms for such material but specify the maximum particle size instead.

Having said the above I would support to deprecate surface=pebblestone as a duplicate of (natural) gravel unless it shall be used specially for its decorative aspect described as:

Again I would support to think about merging the values for dirt, earth and ground to simplify the tagging of such surfaces but this is another issue.

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I generally agree with both de facto description of surface values you posted and with idea of new gravel= tag, though maybe I would prefer a bit different values.

Not sure about surface=pebblestone deprecation.

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Thank you for picking up this feature that I brought up and only recently started to use to portray the state of a compacted track.

Still, pebblestone remains useful. Imagine a stream, first sharp edged gravel riverbed then turning gradually to pebbles. (And yeah, please stop tagging me dyslexic just because I use the definitions given in the wiki.) More still pebblestone is fine for beaches. I’d say, there it even needs a way to tell, how much the pebbles are covered by algae. The pebbles in Krk are wholly different form the pebbles near Split (pun not intended).

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In a riverbed you will find gravel and on a beach as well as there is no significant difference in between gravel and pebbles as said before. Not only to my knowledge, but also defined in Wikipedia:

Gravel is a loose aggregation of rock fragments. Gravel occurs naturally throughout the world as a result of sedimentary and erosive geologic processes. … Gravel is deposited as gravel blankets or bars in stream channels … in near-shore marine settings, where the gravel is supplied by streams or erosion along the coast … and in the deltas of swift-flowing streams.

As such natural gravel is rounded material and not sharp edged as crushed stone. And close to riverbeds you will finde gravel pits (not pebblestone pits) producing gravel by just screening the naturally rounded material … and btw. a beach covered with rounded stones of all kind is usually called a shingle beach - other names ar gravel beach, rocky beack or pebble beach … means all the same, like it or not.

I can’t remember having tagged or called you dyslexic … I even dunno what that means … :wink: … in fact I haven’t given you a single reply in this whole topic so far.

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Thank you! The missing piece!

natural=shingle implies surface=pebblestone
natural=scree implies surface=gravel

It could be oh so easy, yet might be still too hard. Even with the natural, mappers are not always spot on, thats true. And on constructed surfaces, the surface values as originally drafted might be tagging errors quite often.

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Na be so. This is life … :smile:

This sounds so easy but does not reflect reality nor the description in the wiki:

  • natural=shingle implies surface=gravel or pebbles
  • natural=scree implies surface=scree (which is a term of its own, not to be mixed up with gravel)

Quote from the wiki pages:

Shingle is an accumulation of rounded rock fragments, usually pebbles and gravel …

Scree is an accumulation of unconsolidated angular stones … formed by rockfall from adjacent rockfaces

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In the area of my local knowledge we have lots of scree. Traversing paths, if attributed for surface, will for a 100% get surface=gravel. And this is 100% spot on.

I understand your thinking, that it is all the same, that the OSM community is failing to get the differences. If so, I’d say, you rather propose a new surface key, so the distinction could be kept in a secondary attribute:

  • surface=loose_material

Then pebbles, Kies, gravel, Schroppen, Split, shingle &c. can be used to further specify the loose material. This captures quite well, how I have observed use of surfaces gravel and pebblestone. Vespucci users are heavily using those, BTW.

Unfortunately, this will not be able to capture the base, if it is artificially compacted or plain ground. That might be worth to decide upfront.