On Sun, 22 Aug 2021, at 12:08 PM, Little Maps wrote:
Joe, when you talk about reaching consensus, I assume you mean consensus among the
Australian osm community, not the global osm community. Is that right? The highway=track
wiki states: "highway=track does not imply any particular access=* value", and
different countries have adopted different positions on the issue, as described here
(thanks for the link Andrew):
https://wiki.openstreetmap.org/wiki/OSM_tags_for_routing/Access_restrictions
In most countries that have reached consensus, the absence of an access tag on
tracks is implicitly taken to mean that access=yes for motorcars. This includes
Austria, Belarus, France, Finland, Italy, Netherlands, Spain, Switzerland and
the Ukraine. (Brazil, Germany, Iceland and Belgium have partial/proposal
variations on a yes approach). In contrast, two countries went with access=no
(Finland and Denmark). Many countries haven't reached consensus, including
Australia. Have I interpreted this correctly?
Yeah
This message isn't meant to be part of any process for reaching a consensus in
Australia. That discussion needs to be approached far more deliberately and
inclusively. I'm trying to understand whether, to some degree, Andrew and I
have been talking past each other because we have different views on this
fundamental issue.
About 92% of tracks in Australia do not have an access tag (TagInfo Australia),
about 5% have access=private, 1% have yes and 1% have no. If I understand
things correctly (and this is the whole point of this email), this means that:
Yeah 7.85% of tracks in Australia have access=*, 3.95% have motor_vehicle=*,
5.33% have foot=*, 4.15% have bicycle=*.
However if I count access OR motor_vehicle OR motorcar then it's 11.1% of
tracks have vehicle access set.
While we are at it, in this way 12% define pedestrian access and 11% define
bicycle access.
Breaking this down, if I consider (based on a selection of actual values used)
public access includes the tags: designated, destination, permissive,
customers, seasonal, public, dry_weather, yes, 4wd, 4WD
no public access includes the tags: forestry, emergency, agricultural, private,
no, official, military, delivery, prohibited, permit, restricted
Then 1.98% of tracks have public vehicle access and 8.7% of tracks have no
public vehicle access (of all tracks). So where we know the vehicle access then
18% are public and 81% are not public access.
- Strictly speaking, since no consensus has been reached in Australia, 1% of
tracks are known to be open to the public, 1% are known to be closed, and
access is considered to be unknown on 92% of mapped tracks.
- If the community accepted a default position of access=no (i.e. all tracks
without an access tag are implicitly assumed to be closed to public vehicles),
1% of tracks are known to be open to the public, 1% are known to be closed, and
access is assumed to be closed on 92% of mapped tracks.
- If the community accepted a default position of access=yes (i.e. all tracks
without an access tag are implicitly assumed to be open to public vehicles), 1%
are known to be closed to the public, 1% are known to be open, and access is
assumed to be open on 92% of mapped tracks.
Have I got this right? If I have, then would this lead to the following
implications for tagging decisions?
I don't like the idea of a default at all for tracks. It'll lead to a lot of wrong
assumptions, and then you'll have some mappers discouraging setting the access value at
all since it's the "default". It makes it impossible for data consumers to know
what really is yes/no and what is incomplete data. So to this point I say we should not
promote any kind of default value and instead say a missing access/motor_vehicle tag is
incomplete data in OSM.
In my view, data consumers should treat incomplete access/motor_vehicle tags as
no access because I'd rather it miss out on a potentially available route then
route down a private track, but that's a decisions for each data consumer. This
is not the same as promoting a default value within the tagging documentation
in OSM.
- Under the current position of no consensus, a "maximilist" tagging approach
is required, and it's equally important to add access tags to all tracks, whether open or
closed on the ground.
Yes that's my opinion.
- If the community accepted a default position of access=no (i.e. all tracks
without an access tag are implicitly assumed to be closed to public vehicles),
then it's most important to add access tags to all tracks that we know are open
on the ground (with evidence of course). It's less of a priority (but still
useful) to add tags on tracks where access is known to be no/private/etc.
- If the community accepted a default position of access=yes, then it's most
important to add access tags to all the tracks that we know are
closed/restricted on the ground. It's less of a priority (but still useful) to
add tags on tracks where access is known to be open.
- Alternatively, as Andrew suggested, some editors may prefer to adopt the
maximilist approach (tag 'em all) regardless of what decisions we adopt,
because many data consumers (routers etc) may not be aware of, or have the
capacity or interest in basing their products on our consensus.
Yeah I think I've made my point already above.
Thank you all for your tolerance, I'm keen to make sure I haven't misunderstood
any of these principles and their implications. Best wishes Ian
So I can understand, do you think we should have a default value and mappers should not
set the access tag if it's the "default"?
PS. Here is a overpass turbo wizard query to find tracks without vehicle access
set:
highway=track and (access is null AND motor_vehicle is null)
# queries for above stats below
-- public access
SELECT
count(*)
FROM
planet_osm_line
WHERE
(
motor_vehicle IN ('designated', 'destination', 'permissive', 'customers',
'seasonal', 'public', 'dry_weather', 'yes', '4wd', '4WD')
OR (
motor_vehicle IS NULL
AND
access IN ('designated', 'destination', 'permissive', 'customers',
'seasonal', 'public', 'dry_weather', 'yes', '4wd', '4WD')
)
);
-- no public access
SELECT
count(*)
FROM
planet_osm_line
WHERE
(
motor_vehicle IN ('forestry', 'emergency', 'agricultural', 'private',
'no', 'official', 'military', 'delivery', 'prohibited', 'permit', 'restricted')
OR (
motor_vehicle IS NULL
AND
access IN ('forestry', 'emergency', 'agricultural', 'private', 'no',
'official', 'military', 'delivery', 'prohibited', 'permit', 'restricted')
)
);
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