[talk-au] Tracks flagged as missing from government data

Joseph Guillaume josephguillaume at gmail.com
Thu Aug 19 11:58:30 UTC 2021


I'd suggest the problem is with routers assuming that a missing access tag
should be interpreted as access=yes.

If a common understanding was reached that a missing access tag on a
highway=track is *assumed* to imply access=no until proven otherwise, then
it seems the problem goes away?

When armchair mapping, I don't want to have to tag access=private,
fixme="access to be checked" just for the router to have that behaviour.

Cheers,

JoeG


On Thu, 19 Aug 2021, 9:20 pm Little Maps, <mapslittle at gmail.com> wrote:

> Hi Andrew, you raised lots points so rather than replying with a complex
> embedded messages, I’ve summarised my key thoughts below. I’ve indicated
> comments that you made by prefixing them with AH.
>
>
> TL;DR version
>
>
> Tracks are not just for forestry and agriculture, they are for recreation
> too, and are definitely seen as public by data consumers.
>
>
> It’s been repeatedly stated on this forum that public access on private
> roads is a huge social problem. Hence, roads on private land (tracks,
> service, etc) should not knowingly be added to the map unless they carry an
> access=private tag.
>
>
> If you ignore everything else below, P-L-E-A-S-E use “access=private” as
> the default tag for every driveway/service road/track that is not clearly
> on public land.
>
>
> The long version…
>
>
> (1) TL;DR: Tracks are definitely seen as public roads by many data
> consumers.
>
>
> AH: “highway=track are documented as forestry, agricultural or fire
> trails, so shouldn't be considered as public roads by data consumers.”
>
>
> This is not the what the wiki says. As well as agriculture and forestry,
> the wiki lists “outdoor recreation and similar activities” as key
> activities on tracks. Also, it does not state that tracks are not “public
> roads”.  Instead, tracks are not seen as part of “the general purpose road
> network” (ie the roads most 2wd cars drive down).
>
>
> All outdoor apps that I’m aware of (cycling, bushwalking, off-roading etc)
> treat tracks as open to the public unless they are tagged otherwise.
>
>
> For example, if you set the routing options in OsmAnd to prefer unpaved
> roads, it preferentially selects dirt roads and tracks. If you want to
> exclude private roads and tracks you can select an option to avoid private
> roads. Komoot and other cycling routers do a similar thing if one selects
> gravel bike or mountain bike mode. A key problem in using it in Vic is that
> it often sends users down roads that are obviously private farm roads (when
> viewed on a sat image) but which haven’t been tagged as such. I actually
> use it as a tool to find private farm roads (driveways, tracks etc) so I
> can add an access=private tag to them so that other users don’t get sent
> down them ever again.
>
>
> (2) TL;DR version: Roads on private land (tracks, service, etc) should not
> knowingly be added to the map unless they carry an access=private tag.
>
>
> AH: “Do you suggest that maybe tracks on private land shouldn't be mapped
> at all or are you suggesting that they shouldn't be mapped without any
> access tags set?”
>
>
> Happy to see private tracks on the map if - and only if - they are tagged
> access=private. Otherwise I see them as a cancer.
>
>
> Over and over again in the last year or two, this forum has repeatedly
> lamented the problems of having private roads marked as open access,
> including issues like biosecurity, conflict with landowners, safety, fire
> hazards, etc. I can’t think of a topic has been mentioned as often apart
> than copyright breaches. Neville circulated a newspaper article on the
> problem in Google maps just a month ago. There is no benefit to anyone to
> be routed up a road that isn’t open to the public. All it does is make OSM
> unreliable and unsafe.
>
>
> IMO, the key problem with the Aus road network in OSM (except perhaps in
> Qld and N Aus) is not that it has too few roads, but that it has too many.
> We already have a big problem in Victoria with heaps of “paper roads” and
> private roads that are tagged as open and public. It’ll take years to
> remove those we already have. I dread to think that 1000s of new ones will
> continue to be drip fed onto the map from a Map Roulette challenge.
>
>
> AH: “If we add the access tag from Vicmap, then in my view that becomes
> more like an import and less like armchair mapping which this quest is
> geared towards? So we need to decide if we err on the side of caution, omit
> the tag and let on the ground surveys fill in those details or blindly
> trust Vicmap access restrictions.”
>
>
> It may seem crude but, given the immense size of these datasets, I
> actually view this “soft launch” as you call it, as a “TIGER import by
> stealth”. 😉 yeah, I know it’s not a formal import but if an organised
> mapping team took up the challenge and added 200,000 roads without
> including suitable access tags, local mappers will be cursing this
> initiative for decades.
>
>
> I can’t believe that you think you are erring on the side of caution by
> omitting suggested government access data. In what way can this be a
> prudent approach? Even if 10% are wrong, the rest are going to be helpful.
> Hence in contrast to your approach, I suggest “we err on the side of
> caution and include the government tag”.
>
>
> So, please add as many tags as possible that indicate likely access and
> trust the gov data for now. That’s a better default position than no data.
> Perhaps add a note tag saying something like “access data is from Vic gov
> and may need to be updated after ground truthing” or the like.
>
>
> [As an aside, your code says that “4: 'motor_vehicle=no', // permanently
> closed” but I assume you mean no access to vehicles. This does not forbid
>  pedestrian access].
>
>
> AH: “later mappers can follow up with setting access tags once they are
> known”
>
>
> Any suggestion that 100-200,000 private roads could be added to OSM and
> that problems can be sorted out later is a joke. Who is going to do this?
> Every hour spent fixing up errors could be better spent on building the
> map. It would take decades to weed about these problems. There aren’t
> enough local mappers in rural regions as it is. We don’t want future
> mappers to be burdened with the task of fixing tags that could have been
> 99% avoided had a couple of lines of code been added initially.
>
>
> So where now?
>
>
> Building on what you’ve already done, my preferred course of action would
> be as follows…
>
>
> Filter the Vic and SA datasets using land tenure (public vs private) in
> whatever way is practical, and separate both into two separate Challenges,
> one titled “Priority challenge: unmapped tracks on public land” and one
> titled “unmapped roads on private land” or similar. The filtering may not
> be perfect but it should separate most groups reasonably well.
>
>
> The public land dataset will be a great resource and will potentially be
> used by many people. The private roads are of less immediate value to data
> users (and potentially of negative value if private access is not tagged),
> hence the need to keep them separate.
>
>
> Tracks on public land (most of which will be in State Forests and parks)
> can be added as is, including any access tags indicated in the gov datasets
> plus a caveat note tag on the need to ground check access. The basic
> assumption is that access is public unless it is tagged otherwise through
> your data wrangling.
>
>
> For all tracks that are not on public land, instead of highway=track, why
> not set the default tags as highway=service, access=private (and maybe even
> service=driveway) with a note that says something like “private access is
> assumed based on mapped land tenure and may prove inappropriate after
> ground truthing”  or similar.
>
>
> It’s obvious from the Map Roulette map that the majority of the roads on
> private land will be short driveways, so highway=service will be a better
> default tag than track for most.
>
>
> Again, sorry for the long message. I’ve spent the best part of the last
> year working on rural roads, including days of work adding access tags on
> private roads. We need to move on from the standard OSM position of “more
> is better” to a recognition that, outside of forests and reserves, we have
> a great map of public roads in SE Aus. Geometry and tags can always be
> improved but we definitely don’t need heaps more roads added to the public
> network (which is what effectively happens if private roads don’t have an
> access tag). The suggestion that 100s of 1000s of private roads can be
> dumped on without adding private access tags will set us backwards, not
> forward, by years.
>
>
>
> So, if you ignore everything else, P-L-E-A-S-E use “access=private” as the
> default tag for every driveway/service road/track that is not clearly on
> public land. If in doubt, tag it private and add a caveat note to inform
> future mappers how the access tag was derived. Thanks again, Ian
>
>
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