compacted is a “compactable” material which means it NEEDS to contain corn diameter of down to zero (German: “nullanteil”). fine_gravel is non compactable which means it lacks corn sizes down to zero.
So compacted is something like 0-30 diameters where fine_gravel has 5-20 or something.
Flo
Sorry, I’m very late to this topic because I only discovered it through the WeeklyOSM newsletter.
I feel the most important thing about the surface designation is how it determines the ability of different users to use the route. People here keep mentioning cyclists but from an accessibility perspective, other very important considerations are people in wheelchairs and pushing pushchairs.
The precise surface is useful to know because people might be able to estimate whether to risk a route knowing how the surface degrades over time, but would it be as useful in the wiki guide for which tag to use to use the impact on different users? So I would say irrespective of the size of the stones, gravel and fine_gravel will be very difficult for cyclists, wheelchair and pushchair users for any significant distance. If they get mixed up, it wouldn’t be that critical, but mixing this up with compacted would cause more serious problems for users. compacted, regardless of the presence of gravel, fine gravel or stones, will be acceptable for such users. Then the smoothness key can will indicate issues like potholes, ruts and tree root displacement that would make even a tarmacked surface tricky for those users?
The problem with the surface tags for unpaved surfaces is that many mappers do not have the expertise to distinguish between the available options and the more tags are available the more tagging mistakes occur. Add some poor descriptions in the wiki and you will have a mess after a short time. In my area some 90% of all compacted forest roads are tagged “gravel” because that is what people see. The surface is made up of a layer of gravel or crushed stone of different sizes. It is hard and compact but the gravel is still visible.
That is why I tried to make connections between the surface tag and the usability by non-motorized vehicles which could help to find the correct tag. Nevertheless it still remains tricky as there are no exactly defined differences. Each of the discussed tags is overlapping the others. And moreover the durability of unpaved tracks is depending on the scope of traffic. A well compacted forest track may deteriorate heavily during just a couple of weeks if lots of heavy machinery are passing during harvesting works.
A grade 2 track tagged with the correct surface + the appropriate smoothness should give any user a good idea about what they could expect but it still can’t be seen as a guarantee if your bike or wheelchair ride will be pleasurable or not.
I totally agree - it’s almost like a simple flow chart with one or two questions and answers will help. So though a picture helps, asking “would it be easy to push a pushchair here without the wheels sinking into displaced gravel?” would be clearer… Or “How deep is the gravel before you reach a solid surface?”
That’s exactly what I map as fine_gravel.
In German, the most precise term for this is Splitt - you commonly observe this on pathways in cemeteries e.g. In winter it gets spread galore on footways to prevent people from slipping. In spring, it takes the municipal gardening department a tenfold the time to collect than what was spent in winter.
Split is made by crashing gravel, which in German colloquially is called pebbles,
Not for the first time, I’m thinking that it’s a shame that OpenStreetMap wasn’t invented in Germany but instead in the UK. The terminology used would have been so much more precise. 
Nah, I’d be cautious with such a statement, because German speaking engineers and common lads, self-made concrete mixers, and also Geologists, have quite different understandings of gravel (Schotter) and pebbles (Kies). In fact, opposite ones.
PS: Splitt is an English term 
In Germany we only invent such easy to use things like “Einheitliche Datenbankschnittstelle” (EDBS) and “Normbasierte Austauschschnittstelle” (NAS)
In Germany we have a single word for stable, sty, pen, cot and any other “building for animals”.
And if you say “umfahren”, it can mean to drive around and to drive over, the same word.
This is the precision of German
Pfff, whether you drive around or over something: you’re behind the barrier 
Jokes aside, there are areas where German is more precise then English, but in some areas, it’s the other way around. At least OSM doesn’t force people to type umlauts 
As an avid surface=compacted tagger that only recently started to use gravel and pebblestones for deteriorated compactions, this topic quite nags me.
I see two schools of thought, and wiki edits by Germans may very well nowhere made the waters less murky:
Browsing the web, similar distinctions can be found in commerce - e.g. Was ist der Unterschied zwischen Kies, Splitt, Schotter & Co.? | Blog | Schicker Mineral - a business that sells rocky materials. And indeed, they use size as a defining measure https://www.schicker-mineral.de/media/image/8b/f1/5b/36-uebersicht-sand-splitt-schotter-1.jpg - There I learned, that was called gravel in OSM until recently, is called Schroppen in German, though not from Germany, my native language
Fine gravel (= Feinkies) is not a defined term, it is used in common language for gravel in the sizes from aopprox. 2-8 mm, as described here. There is no definition for fine gravel in road engineering, just to repeat this once again.
The term “Feinschotterweg” (= fine gravel track) is sometimes used in common language to describe tracks with a compacted surface where the top layer is made of a relatively fine compactable mixture in the size range from approx. 0 - 8 mm or maximum 0-16 mm (which are common mixtures available in every gravel pit). Nevertheless it describes a compacted surface.
Splitt is the correct german term for crushed stone in the sizes between 2 and 32 mm, followed by “Schotter” for 32-63mm, although in common language people understand Splitt as being a fine material like 2-8 mm or the like.
Kies is the correct german term for natural (round) Material in the sizes between 2 and 63mm. This term ist used for the Material in bulk only. If you look at individual stones you look at Kiesel(stein).
Sometimes the difference between a single Kiesel(stein) and a heap of Kies is translated to a single pebble and a heap of gravel, but that seems not to be correct. In construction business no one talks about pebbles, all that round stuff is called gravel.
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 double to surface=gravel. Attractivity of the stones (which is not a fact but just an opinion) used for 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.
I oppose The OSM Wiki definition is not demanding at all: pebblestones (Kies in German) is rounded material, and gravel (Splitt and Schroppen in German) is material with sharp edges. No need for an engineering degree to differentiate.
BTW: The German term Schotter does not say anything about this. Though, when people order Schotter from a seller, they are picky about the difference: To make concrete, they want rounded rocks, because that gives better strength; For paving streets with asphalt, rocks with edges are fine in the mix and possibly even preferred. It is both Schotter in German, most often translated into English as gravel. This is also in line with the meaning the word has in Geology, just rocks by the side of a stream/river. Edginess just a factor, more in the upper part, less in the lower part.
I still wonder, if there is anything to come out of this discussion?
PS: That is why compacted is actually very much needed, when it is not possible to tell rounded from edgy, because it is just a mix of different size of both, but the surface is clearly man_made and not just ground
I have on my TODO list rewrite of related wiki page though I hope a bit that someone else will do it first :)
No, not at all. Pebbles as well as gravel are terms for rounded material and the only difference is the attractivity of pebbles being more shiny and colourful. See the sample pics here.
Additionaly in common language gravel is used for all kinds of loose stone material notwithstanding if it is rounded or sharp edged.
The correct term of sharp edged (broken) material is “crushed stone”. If you want to learn more about these terms have a look at the english Wikipedia pages for gravel and crushed stone.
We are discussing here about “Schotter” for road surfaces and in this context Schotter describes broken material contrary to “Kies” which is naturally rounded.
Im Bauwesen bezeichnet man als Schotter kantige, gebrochene Mineralstoffe mit einer Korngröße zwischen 32 und 63 Millimeter, meistens zur Verwendung im Verkehrswegebau. Bei runden Formen dieser Korngröße spricht man im Bauwesen nicht von Schotter, sondern von Kies.
To read more have a look at the Wikipedia page for Schotter.
It is not that difficult to tell if the material used for a track surface is rounded or sharp edged by just looking at it. In road/track construction in Europe you will in most cases find crushed stone mixtures (like 0-32) for compacted surfaces, because the sharp edged material gives a much better solidity when compacted. A 0-32 mixture of rounded material can be compacted but will never be as hard and solid as the before mentioned due to the round surfaces of the stones.
I did just quote the definitions given in the fine OSM wiki. I have seen, you started a quest to make both read the same.
Given enough use, you will see gravel turn into pebbles.
I would not agree that attractivity is the only difference. Gravel, having sharply cut / crushed edges, is much more likely to be stable as sharp edges will lock on one another (at least partially - in case of very loose gravel), while smooth edges of pebbles are much more slippery and loose. Try riding a bicycle on each and you’ll see what I mean. One is uncomfortable, other is suicidal.
Also, pebble beaches (to which you link) are my favourite (don’t like sandy ones as sand gets into everything!), and crushed gravel ones with sharp edges would definitely be amongst the most horrible ones (probably tied for worst position only with freshly laid smelly half-melted-from-the-summer-sun tarmac beach 
).
So I absolutely do not agree that something which is the best should be marked as a duplicate of something which is the worst.
Additionaly in common language gravel is used for all kinds of loose stone material notwithstanding if it is rounded or sharp edged.
OSM tags are not “common language”. We’ve had clearly defined surface=pebblestone for more than a decade: “Pebbles are stones rounded by waves or river flow”. So if it is made only of pebbles, then it is surface=pebblestone. If it is not, then search for another, better matching value of surface=*.
@Map_HeRo if you think that surface=gravel is confusing, and thus should better be deprecated and replaced by several more fine-grained (excuse the pun) tags, that I would agree with (although I personally probably would not volunteer to dedicate the rest of life to pursuing that holly crusade).
However, suggesting that we should deprecate several well-defined tags (like surface=pebblestone) and replace them with one unclear and fuzzy tag representing all of them (like surface=gravel), I definitely do not agree with in the least.
I am not convinced that in typical language, or in use by OSM mappers gravel is used for rounded stone.
@Matija_Nalis @Mateusz_Konieczny
As your replies are reflecting the issue gravel vs. pebbles I posted a reply in view of the distinction in the topic I opened separately. Just want to point out that what I said is not just a thought of mine but based on the information picked up from various internet sources.
