[talk-au] Gravel roads surface tagging
osm.talk-au at thorsten.engler.id.au
osm.talk-au at thorsten.engler.id.au
Sat Mar 6 23:44:03 UTC 2021
I don’t really have an answer to any of the questions raised by this thread… but this might be relevant:
https://simple.wikipedia.org/wiki/Particle_size_(grain_size)
φ scale
Size range
(metric)
Size range
(approx. inches)
Aggregate name
(Wentworth Class)
Other names
< −8
> 256 mm
> 10.1 in
Boulder <https://simple.wikipedia.org/wiki/Boulder>
−6 to −8
64–256 mm
2.5–10.1 in
Cobble <https://simple.wikipedia.org/wiki/Cobble>
−5 to −6
32–64 mm
1.26–2.5 in
Very coarse gravel <https://simple.wikipedia.org/wiki/Gravel>
Pebble <https://simple.wikipedia.org/wiki/Pebble>
−4 to −5
16–32 mm
0.63–1.26 in
Coarse gravel <https://simple.wikipedia.org/wiki/Gravel>
Pebble <https://simple.wikipedia.org/wiki/Pebble>
−3 to −4
8–16 mm
0.31–0.63 in
Medium gravel <https://simple.wikipedia.org/wiki/Gravel>
Pebble <https://simple.wikipedia.org/wiki/Pebble>
−2 to −3
4–8 mm
0.157–0.31 in
Fine gravel <https://simple.wikipedia.org/wiki/Gravel>
Pebble <https://simple.wikipedia.org/wiki/Pebble>
−1 to −2
2–4 mm
0.079–0.157 in
Very fine gravel <https://simple.wikipedia.org/wiki/Gravel>
Granule <https://simple.wikipedia.org/wiki/Granule>
0 to −1
1–2 mm
0.039–0.079 in
Very coarse sand <https://simple.wikipedia.org/wiki/Sand>
1 to 0
½–1 mm
0.020–0.039 in
Coarse sand <https://simple.wikipedia.org/wiki/Sand>
2 to 1
¼–½ mm
0.010–0.020 in
Medium sand <https://simple.wikipedia.org/wiki/Sand>
3 to 2
125–250 µm <https://simple.wikipedia.org/wiki/Micrometre>
0.0049–0.010 in
Fine sand <https://simple.wikipedia.org/wiki/Sand>
4 to 3
62.5–125 µm
0.0025–0.0049 in
Very fine sand <https://simple.wikipedia.org/wiki/Sand>
8 to 4
3.90625–62.5 µm
0.00015–0.0025 in
Silt <https://simple.wikipedia.org/wiki/Silt>
Mud <https://simple.wikipedia.org/wiki/Mud>
> 8
< 3.90625 µm
< 0.00015 in
Clay <https://simple.wikipedia.org/wiki/Clay>
Mud <https://simple.wikipedia.org/wiki/Mud>
>10
< 1 µm
< 0.000039 in
Colloid <https://simple.wikipedia.org/wiki/Colloid>
Mud <https://simple.wikipedia.org/wiki/Mud>
https://www.boral.com.au/products/quarry-materials/aggregates/rail-ballast
Single size aggregate used in rail track construction. Generally has a nominal size of 63mm or 53mm.
Calling a surface with stones the size of rail ballast “gravel” isn’t exactly wrong. Calling a surface pretty close to sand “gravel” isn’t wrong either.
But given that surfaces within that range have significantly different properties, it will be necessary to classify them differently.
I think the majority of English speakers would associate the term “gravel road” with something in the fine to medium range.
From: Mateusz Konieczny via Talk-au <talk-au at openstreetmap.org>
Sent: Saturday, 6 March 2021 21:41
Cc: OSM Aust Discussion List <Talk-au at openstreetmap.org>
Subject: Re: [talk-au] Gravel roads surface tagging
Mar 6, 2021, 12:11 by mapslittle at gmail.com <mailto:mapslittle at gmail.com> :
Hi Mateusz, thanks for your thoughts. This may be a matter of language rather than substance, but personally I recoil at your suggestion that any one tag, whether it is compacted or any other, is the “correct one” as you wrote on the wiki.
In that situation it is definitely overreach. I was looking for exactly this kind of review.
In some cases tags are actually clearly correct/incorrect - I though that it is such case
but I was clearly wrong.
I edited https://wiki.openstreetmap.org/wiki/Tag:surface%3Dgravel to remove misleading info.
It should be edited to mention evidence and analysis based ion tag popularity
>From discussions to date, it seems like railway ballast is not a common surface to drive / ride upon, no matter what one calls it.
I can confirm that for Poland. Now that I see this data - there is plenty of "droga żwirowa" with
far smaller pieces of rock than track ballast and not compacted and not qualifying for surface=fine_gravel.
Probably surface=gravel was used for them
But these are the stats on surface = gravel, compacted and fine_gravel from a few countries around the world.
(...)
The numbers show that, either (1) an awful lot of roads are indeed made of railway ballast (and hence ‘gravel’ is indeed the ‘correct’ term for many of the world’s roads) or (2) most mappers across the world are using the tag ‘gravel’ to describe the roads they drive / ride on, regardless of the definition in the wiki.
We have no way of ‘correcting’ these ‘wrong’ tags, short of starting again with a new system. Hence I’m curious at what stage one must acknowledge that the current definitions of gravel, compacted, fine_gravel simply do not apply to the way that world has been mapped in openstreetmap. Surely, it is somewhat pointless to claim that descriptions that are rarely used are ‘correct’ and the world is wrong?
This should be summarized and added to wiki. I used basically the same reasoning for
https://wiki.openstreetmap.org/wiki/Tag:bicycle=no#Pushing_bicycle
I guess that next step after that is
- waiting for further comments whatever something important was missed
- announcing "good" news on global tagging mailing list
- updating description on https://wiki.openstreetmap.org/wiki/Key:surface
- inventing tag for gravel so large to resemble track ballast,
- maybe also invent new tag for small gravel
Hopefully someone(TM) will do at least some of above.
And start migrating away from burned surface=gravel tag (like it is happening with surface=cobblestone).
That has over 1 500 000 uses. Wonderful :(
I would deeply recommend using surface=compacted for roads with compacted gravel
("mixture of larger (e.g., gravel) and smaller (e.g., sand) parts, compacted (e.g., with a roller),
so the surface is more stable than loose gravel")
and retagging surface=gravel where clear tags are available
PS Sorry for starting a new duplicated thread - I was not expecting that exactly this was
discussed right now and I failed to check archives. Sorry.
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