Key surface not only used on roads. I have learned that “Fallschutzkies” (German term) on playgrounds is very helpful in avoiding severe hurt when dropping off a “Reck” when trying a stunt with the hands in the wrong direction.
From childhood memories, I remember fine_gravel to the centre of the earth footways in the cemetary. Not sure whether perception of depth changed since then or thickness of the fine gravel layer.
PS: In vein of first paragraph, surface=pebblestone also mostly found on beaches, isn’t it?
If a track surface is loose fine gravel I will tag it surface=fine_gravel. If the fine gravel is bound with even finer material to a fixed layer I will tag it surface=compacted.
And if you find a “nothing but fine gravel” track of reasonable thickness (> 5 cm) where a normal bicycle wheel will sink in such a way that riding the bike becomes impossible make some photos documenting the depth of the gravel layer, post it here and then we can discuss how to tag that track or path.
FYI, I updated the Wiki article – mostly, it was just formatting and cleanup of duplicates. I also added some musings which may or may not accurately summarize this discussion (which, however, I find quite relevant for the topic, if anything to describe volatility of distinctions between gravel, fine_gravel, compacted and pebblestones).
I think the documentation should reflect usage a bit more. Just my guess, but out in the wild, fine_gravel is still mostly mapped when there is a thin layer of fine gravel over a compacted base, at least when found on roads and paths. Understandably, this is really hard to prove, just what I observe in the area of my local knowledge.
PS: I guess, most of the problems stem from the fact, that key surface is also used on things different from tracks, outdoor seating areas or playgrounds come to mind.
While I generally agree that Wiki should be more descriptive and less prescriptive, in this case the best description of current usage would be
Bloody mess.
Compare e.g. surface=gravel, which goes on to considerable detail to explain how the tag usage is a bloody mess, and the most that can be assumed is that the road has been improved with some kind of gravel at some point in history. In other words, not much.
I then turned my attention to surface=pebblestone, which until yesterday looked like this, i.e. only explaining what “pebblestone” means, but not how it is used in OSM. The combination with natural=beach immediately sprung to my mind, so I added it to the article. Indeed, according to taginfo, the combination is used 4747 times. So far, so good…
…however, it is also used with 145937 highways, of which 49647 track, 29456 footway and 25012 service. From those data, I can only assume it means the same as surface=gravel, i.e.:
Bloody mess
So, I confess to wikifiddling with Tag:surface=pebblestone. I may have made the article more comprehensive, but not necessarily more informative from a “tagging standardization” viewpoint.
However, I would not ascribe all our tagging woes to wikifiddling – in this case, it has lot to do with loose definitions in natural language. The word gravel itself is skunked in English, since it may mean specifically a) pebblestone of natural origin b) crushed rock c) either of the above. Many other languages have the same problem that they do not reliably distinguish a) from b), and in many use cases the distinction does not matter much (for example, which one you will use as aggregate in concrete).
Pebbles are mostly smooth but, dependent on how frequently they come in contact with the sea, they can have marks of contact with other rocks or other pebbles. (…) Pebbles on Earth exist in two types of locations – on the beaches of various oceans and seas, and inland where ancient seas used to cover the land.
The result is a smooth, rounded appearance.
Because river current is gentler than the ocean waves, river pebbles are usually not as smooth as beach pebbles.
so that would match expectations of roundness.
Why that deserves separate surface value always confused me.
“smooth” does not exactly match “round”. Any gravel including pebble size is rounded and smoothened by influence of water. Natural gravel/pebbles is usually excavated in a gravel pit and just sorted by sieving the different sizes.
The sharp edged material also known as gravel is in fact “crushed stone” and produced by crushing rock in a quarry.
Most people are not aware about the difference (why should they?) and that is why we have this
Thank you. That was also my point, although I did not communicate it as effectively. (I had also thought that gravel only refers to crushed stone, until I read up a bit more on the subject). Wikipedia sums it up:
Gravel occurs naturally on Earth as a result of sedimentary and erosive geological processes; it is also produced in large quantities commercially as crushed stone.
I suppose writing a “Terminology” section at Tag:surface=gravel (or making it a template and including in all related surface pages) might help readers’ understanding (if it only could help clearing up the tagging ).
Walking on both barefoot would make some differences very apparent. Fairly different outcomes for bicycle tire durability as well, if pebbles were widely used on roads.
Real world usefulness of having this in OSM is another matter, but I’m under the impression that’s normally not a concern.
Pebblestone is round, gravel may be round or not (the term in construction and geology - not in everyday language). Problem here is that “gravel” is not as specific as for instance the German terms “Kies”,”Schotter”,”Split”. I guess it’s the same problem in other languages. This leads to a lack of clarity in the translations and usage.
First, you don’t demonstrate the meaning of words used by Shakespeare by quoting some specialist jargon meaning from wikipedia. (Incidentally, Shakespeare did use both words to describe small natural stones in or near water.)
Second, OSM English doesn’t always correspond to common nor specialist English. The descriptions on surface wiki seem unchanged since 2008 and show two very different things.
This is correct and applies for lots of terms used in OSM. For sure there are different reasons for this and one may be that the person writing it into the wiki did not know better. In some cases it definitely makes sense to use modified terms for OSM use, in other cases it just causes irritation, misunderstanding and endless discussions, like in the case of gravel vs. fine gravel vs. pebbles.
I’d suggest:
).