Re: [talk-au] highway=track update

[Little Maps]

Thanks for the detailed history Michael!

As you say, most of the ways tagged ‘gravel’ in Australia could probably be 
re-tagged as ‘fine_gravel’ to more accurately follow the wiki and to accord 
broadly with common usage of the word gravel. 

Re compacted vs fine_gravel, personally I can’t tell the difference from the 
descriptions in the wiki. Both descriptions could be applied to the same 
stretches of rural road in many parts of Australia. Two problems are: the 
descriptions require mappers to know what is underneath the top surface layer 
and to know how the surface was made or applied (e.g. was it ‘rolled’ or not?). 
These aren’t mutually exclusive I’d have thought. Neither feature is common 
knowledge presumably, and both might be somewhat irrelevant if the road hasn’t 
been re-surfaced for a decade or so.

In an earlier message you said that you distinguished fine_gravel from 
compacted surfaces depending on whether the surface was loose (fine_gravel) or 
firm (compacted) when ridden on a bike. This seems to be a completely different 
distinction to that described in the wiki.  Wouldn’t this vary seasonally, and 
across the road surface from the edge to the middle, and over time, depending 
on how recent the road was maintained? 

It would be valuable to have a reliable distinction between earth/dirt/ground 
road surfaces (which may be bulldozed every so often but little more) from 
‘improved’ compacted/fine_gravel/gravel surfaces, but distinctions beyond this 
seem unlikely to eventuate anytime soon. In the meantime, the numbers show that 
mappers prefer to use ‘gravel’ to indicate ‘improved’ road surfaces (i.e. 
compacted/fine_gravel etc), even though this usage contradicts the 
idiosyncratic definition in the wiki. The most obvious downside to this 
practice is that we don’t have a reliable way to distinguish the small number 
of road surfaces that are covered with coarse ‘railway ballast’ unfortunately.

If you’re interested, the taginfo data on surfaces in Australia is really 
interesting...

https://taginfo.geofabrik.de/australia-oceania/australia/keys/surface#values

Thanks again for your insights and for 16 years of great mapping!  Best wishes 
Ian


___
Talk-au mailing list
Talk-au@openstreetmap.org
https://lists.openstreetmap.org/listinfo/talk-au

Re: [talk-au] highway=track update

[Josh Marshall]

This raises the question: how did the surface=gravel tag end up getting defined 
as large aggregate/railway ballast anyway, given it appears at odds with almost 
everyone’s usage of it, including other significant online references such as: 
https://en.wikipedia.org/wiki/Gravel_road (which matches the vernacular 
perfectly)?? Any OSM old-timers recall enough to comment? Is there actually 
anywhere in the world where roads are commonly done this way?

With regard to:
> Hi Josh and co, I ride a “gravel bike” on dirt roads that are signposted as 
> “gravel road”but definitely don’t fit the OSM definition of gravel = railway 
> ballast. 
and Michael’s
> I don't map much in the US but do in Australia and Sweden. In both countries, 
> I have rarely come across what I consider to be gravel roads, instead 
> consider most unpaved roads and tracks to be 'dirt' or 'compacted':

Same here. I might provide a single counter-example; the major through road in 
the Watagans near me was actually lined with this large ballast last time I 
rode through; an absolute nightmare to ride on, and I can’t imagine it’s too 
kind on vehicles either. Presumably an initial step before further surfacing? 
Has anyone else seen this surface?



> On 23 Feb 2021, at 8:44 pm, Little Maps  wrote:
> 
> Hi Josh and co, I ride a “gravel bike” on dirt roads that are signposted as 
> “gravel road”but definitely don’t fit the OSM definition of gravel = railway 
> ballast. Because of the common usage of gravel as a variably textured dirt 
> road in Australia, we face a massive uphill battle to get accurate, specific 
> unpaved road surfaces in OSM. Here’s some data from Overpass Turbo queries of 
> all unpaved highway surfaces in Victoria. This includes all highway tags (inc 
> roads and paths) not just tracks:
> 
> Surface  Number  Percent
> unpaved   48664   80
> gravel615910
> dirt  45598
> compacted 642 1.1
> sand  406 1
> fine_gravel   230 0.4
> earth 46  0
> Total 60706   100
> 
> In case that’s illegible, if you add all of these unpaved/dirt/gravel ways, 
> 80% are tagged with a generic unpaved tag (which is entirely accurate if not 
> especially precise). Gravel is the next most common category, accounting for 
> 10% of ways. Apart from dirt at 8%, the rest are used very rarely. 
> 
> My guess from tagging surfaces on a lot of unpaved roads is that perhaps 80% 
> of the roads tagged as gravel do not satisfy the OSM wiki definition and 
> should be tagged as something else. Interestingly, the two most relevant tags 
> for formed, unpaved surfaces - compacted and fine_gravel - are very rarely 
> used (around 1% each). There are probably more ways that have fence-sitting 
> tags like “dirt; sand; gravel” that end up being pretty meaningless. 
> 
> Adding precise surface tags may be simple on roads that are freshly 
> maintained but on roads that haven’t been maintained for a while they’re 
> often pretty difficult to assess anyway. 
> 
> Personally, I feel that there’s often too much emphasis in OSM on precision 
> (i.e. use detailed sub-tags) at the expense of accuracy. I believe most of 
> the generic unpaved tags are accurate. I wish I could, but unfortunately I 
> don’t believe many of the specific sub-tags are especially useful. (Sand is a 
> goody though!). Cheers Ian
> 
>> On 23 Feb 2021, at 5:22 pm, Josh Marshall  wrote:
>> 
>> 
>> The approved OSM tag for surface=gravel 
>>  refers to railway ballast, 
>> not the fine crushed rock or natural surface that usually occurs on unpaved 
>> roads in Australia. However we call the fine unpaved surface "gravel" in 
>> common parlance, and many unpaved roads that don't constitute gravel as 
>> described in the OSM wiki have been tagged as gravel here, erroneously 
>> depending on your point of view.
>> 
>> This is a matter of interest to me too. I spend a substantial amount of time 
>> running+riding on fire trails in NSW (all highway=track), and the surface 
>> type is useful and indeed used in a number of the route planners I use. I 
>> have changed a few roads back to 'unpaved' from 'gravel' due to the rule of 
>> following the description in the surface= guidelines rather than the name. 
>> 
>> My question then however, is exactly what to tag the tracks beyond "unpaved".
>> 
>> There are definitely sections that are somewhat regularly graded and appear 
>> to have extra aggregate/fine gravel added. From the surface= wiki, these 
>> most closely align with surface=compacted. But fine_gravel is potentially an 
>> option too. Many of these are 2wd accessible when it is dry. (Typically 
>> smoothness=bad.)
>> 
>> There are also others, usually less travelled, which are bare rock, clay, 
>> dirt, sand, whatever was there. Is it best just to leave these as 
>> surface=unpaved, and add a smoothness=very_bad or horrible tag? None of the 
>> surface= tags really seem to apply.
>> 
>> 

Re: [talk-au] highway=track update

[Michael Collinson]

I don't map much in the US but do in Australia and Sweden. In both 
countries, I have rarely come across what I consider to be gravel roads, 
instead consider most unpaved roads and tracks to be 'dirt' or 'compacted':


https://wiki.openstreetmap.org/wiki/Tag:surface%3Dcompacted

Apropos the current discussion, I wonder what other mappers think? 
Especially if you have any road engineering background in Australia. I'd 
like to fall in with a consensus.


Background: I mostly look at tracks/roads as a cyclist. If my tyre is 
mostly resting on small stones of various sizes, then it is gravel and 
riding is generally tough with tendency to skitter. If my tyre is 
resting mostly on (often rollered) dirt with usually embedded very small 
stones  for cohesion and traction, then I am on a compacted surface and 
riding is much easier. Here in Sweden, almost all unpaved public and 
residential roads are the latter as are many logging and farm tracks. A 
half-decent compacted surface can often be car driven at 70 kmph, not 
something I'd fancy on a gravel road.


I could have sworn there was a good Wikipedia page on compacted road 
surfaces but I cannot find it now or anything similar, perhaps called 
something else. It is a deliberate technique that goes back to Roman 
times, (perhaps there are some in Waga Waga :-) ).


Mike

On 2021-02-23 07:22, Josh Marshall wrote:


The approved OSM tag for surface=gravel
 refers to
railway ballast, not the fine crushed rock or natural surface that
usually occurs on unpaved roads in Australia. However we call the
fine unpaved surface "gravel" in common parlance, and many unpaved
roads that don't constitute gravel as described in the OSM wiki
have been tagged as gravel here, erroneously depending on your
point of view.


This is a matter of interest to me too. I spend a substantial amount 
of time running+riding on fire trails in NSW (all highway=track), and 
the surface type is useful and indeed used in a number of the route 
planners I use. I have changed a few roads back to 'unpaved' from 
'gravel' due to the rule of following the description in the surface= 
guidelines rather than the name.


My question then however, is exactly what to tag the tracks beyond 
"unpaved".


There are definitely sections that are somewhat regularly graded and 
appear to have extra aggregate/fine gravel added. From the surface= 
wiki, these most closely align with surface=compacted. But fine_gravel 
is potentially an option too. Many of these are 2wd accessible when it 
is dry. (Typically smoothness=bad.)


There are also others, usually less travelled, which are bare rock, 
clay, dirt, sand, whatever was there. Is it best just to leave these 
as surface=unpaved, and add a smoothness=very_bad or horrible tag? 
None of the surface= tags really seem to apply.



On Tue, 23 Feb 2021 at 16:45, Little Maps > wrote:


Hi Brian and co, in Victoria and southern NSW where I've edited a
lot of roads, highway=track is nearly totally confined to dirt
roads in forested areas, as described in the Aus tagging
guidelines, viz: " highway=track Gravel fire trails, forest
drives, 4WD trails and similar roads. Gravel roads connecting
towns etc. should be tagged as appropriate (secondary, tertiary or
unclassified), along with the surface=unpaved or more specific
surface=* tag."

In your US-chat someone wrote, "...in the USA, "most" roads that
"most" people encounter (around here, in my experience, YMMV...)
are surface=paved. Gravel or dirt roads are certainly found, but
they are less and less common." By contrast, in regional
Australia, most small roads are unpaved/dirt/gravel.

In SE Australia, public roads in agricultural areas that are
unpaved/dirt/gravel/etc are usually tagged as highway=unclassified
(or tertiary etc), not highway=track. There are some exceptions in
some small regions (for example in the Rutherglen area in NE
Victoria) where really poor, rough 'double track' tracks on public
road easements have systematically been tagged with highway=track
rather than highway=unclassified. See here for example:
https://www.openstreetmap.org/#map=13/-36.1424/146.3683
.
However, this is not the norm in SE Australia and across the
border in southern NSW, this type of road is nearly always tagged
as unclassified, as it is elsewhere in Victoria. In SE Australia,
my experience is that tracks are tagged in the more traditional
way, and not as has been done in the USA.

If I could ask you a related question, what do you US mappers call
"gravel"? The approved OSM tag for surface=gravel
 refers to
railway ballast, not the fine crushed rock or natural surface that
usually occurs on