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

Little Maps mapslittle at gmail.com
Thu Aug 19 11:09:33 UTC 2021


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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