Should we strive for a global or regional consensus for things like trail visibility & difficulty (sac etc), and possible pathless paths?

Original post from the first version of this thread:

sac_scale is the global standard on OSM for describing the difficulty of moving over terrain for trails/paths/wilderness ways/etc. This isn’t ideal as mappers in areas that don’t use SAC aren’t familiar with it, and users that come across it don’t really know what it means. I can mentally map T1-4 pretty easily, but don’t feel like I have a good grasp on where the lines between 4-6 would be (and to be fair, there will never be a 100% consensus, but having been on trails rated a certain way would help).

Two possible approaches I can see to this:

1 - create some universal keys that map to different localized systems

It seems like adding some sort of osm_scale (inspired by @Hungerburg) that maps onto various regional ratings systems would be useful. sac_scale would still exist as is. This isn’t necessarily what I would propose for this osm_scale, but it’s an example of the concept.

I was spitballing in the failed highway=scramble thread to try and come up with a cross-cultural set of buckets and came up with:

highway=path - what any person able enough to walk and moderately fit is capable of doing.

Class 1 YDS, SAC T1-2, Austria Blue, SWW Yellow, CAI T & E

highway=demanding-path - might need hands for balance, or require some upper body strength (I guess a ladder or mantle would fall in here?) but you’re not climbing rock or have any significant direct exposure. having some experience hiking is highly recommended, but you don’t need to be a climber.

Class 2 YDS, SAC T3, UAII 1, Austria Red, SWW White-red-white, CAI EE

highway=scramble - requires use of hands to pull yourself up terrain. it’s generally simple climbing that is done without a rope but may be uncomfortable to people without technical experience and have fatal consequences. While far simpler than technical climbing, having climbing experience will help greatly. No extra equipment (like ropes, harnesses, etc) is expected to be used. Simple Via Ferrata routes with anything complicated than a ladder or a railing would probably fall into a scramble due to technique and physical strength required?

Class 3 YDS, SAC T4-6, UAII 2, Austria Black, SWW White-blue-white, BMC Grade 1, Schall Scale A, Hüssler Scale K1

2 - Add different rating systems for different countries

Have keys for the the British scrambling system, Austrian numbers, US YDS, the sales with umlauts in them, CAI, etc. Mapping applications would have to support this, but many mapping applications are region specific (AllTrails, Gaia, Caltopo in the US. OsmAnd, LocusMaps, etc in Europe). There’s a Russian system for rating passes in there already.

overview of past events:

There was one response on topic with some good data in the previous thread worth looking at, the rest is (an admittedly engaging) discussion on whether tags that involve some, difficulty, with verifiability belong on OSM. I’ve copied it and my response below:

Please ignore off topic comments, there’s existing places for them if a new topic doesn’t need to be created. :slight_smile:

New thoughts:

On the thread on “pathless paths” I outlined how alpine norms in the US are to have off-trail routes that have yet to develop an informal/social/foot trail described by nodes vs ways. Some European users were more interested in having them be ways - which could be a number of different factors:

  • less actual undeveloped wilderness in the EU vs US, pretty much anywhere accessible on terrain that can hold a path already has a path
  • less gentle basins due to the milder glaciation in the western US that are more conducive to “find your own routes” vs needing to thread the needle for a single safe route somewhere.
  • other less tangible social norms

Having some kind of death match on whether such routes should be ways or collections of nodes doesn’t seem ideal, as there is no pure right or wrong answer. One thing would be to have both be available as different options with some guidance, along with a default per region.

Another useful aspect of it would be to spin out updated keys that can be adopted regionally, using the old ones as a fallback. trail_visibility is a generally disliked key, though for different reasons, but many of those that aren’t fans of it see it as too ingrained to change. I’d argue that, but it can be sidestepped by say riffing on this great proposal by @Adam_Franco and creating say a us_trail_visiblity (though that wasn’t his stated intent) that could be used for stippling, then if it doesn’t exist the existing trail_visiblity can be used as it currently is. This would be a relatively light load to add to the logic in mapping applications, and over time could help shift use of tags and have things evolve organically (at the cost of some, hopefully not eternal, if/else statements).

Although the YDS system is nearly universal for climbing in North America, it’s rare for anything easier than a YDS 3 to be formally rated (and even 3 and 4 are uncommon). I’m not aware of any widespread system for rating hikes in North America.

The lower spectrum YDS is used heavily for passes, peaks, and other off-trail routes - the THE HIGH SIERRA: PEAKS PASSES TRAILS, 3RD EDITION - R.J. SECOR has hundreds of usages of Class 1 and 2 for routes, and a lot of Class 3 & 4. There is an offshoot of YDS with the SPS scrambler system, I’m not a huge fan of it but there’s hundreds of Class 2-3 peaks labeled with that.

I do agree that it isn’t really used for formal trails in the US, but all it does is rate terrain (well mode of travel over terrain) regardless of whether it is trailed or not. YDS is one of weaker use cases actually!

I personally find it somewhat useful for thinking of trails, as I see people struggling or complaining about on poorly maintained or abandoned trails that have a lot of Class 2 and some intermediate 3 mantles, whereas a well maintained Class 1 trail is likely to be pretty friendly for all even if it includes T2 terrain on it. It’s not a perfect map, but there’s a higher chance of an outdoorsy person in the US being familiar with YDS than SAC (I never knew about it before getting into OSM, and despite having spent years in the backcountry have not encountered it in the real world). I can grok T1-4 very easy, but I’m unsure of what is truly T5-6 because I’ve never been on anything rated with it, which harms my ability to use it effectively.

Let’s say 5% of hikers are aware of YDS in the US (random numbers), and 0.1% of them are aware of SAC. That’s not a huge absolute difference, but that number would be a LOT higher for the many countries that do explicitly rate trailed terrain. I have to imagine there’d be better localized results if people were using systems they were familiar with.

From the other angle, if there was some sort of universal osm_scale that tried to map existing systems there’s a higher chance that someone is aware of one of the systems on it - if they aren’t familiar with any systems then they’d have to learn a new one anyways.

@Minh_Nguyen That makes sense to me - maps could be set to always prefer the local system, and then fallback to the global one (similar to my thoughts on trail_visibility above).

In Austria it would be:

  1. if austrian_scale (unsure of the formal name for blue/red/black, @Hungerburg?)
  2. else osm_scale
  3. else sac_scale (for historical fallback)

Switzerland would be:

  1. if sac_scale (it is local)
  2. else osm_scale
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I wonder if, in the U.S., the whole notion of systematized ratings is less common than the practice of just assigning an informal description to get the point across. Words like “easy”, “moderate”, and “difficult” get posted on a sign and therefore mappers historically tagged them in name in parentheses, but they don’t necessarily form a system that you could name. It could be something like a freeform difficulty key, or maybe difficulty:ref, by analogy with a similarly intentionally heterogeneous key, level:ref.

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The Sierra Club has a ratings system based grade and elevation gain. There’s also another system that I can’t remember the specifics of right now. But I have yet to see either one in use anywhere. Mostly it’s just informal descriptions. At least outside a few situations where parks have their add hock systems, but it’s extremely rare from what I’ve seen.

You could easily create a tagging scheme for trail difficulty based on the Sierra Club’s classifications though and it would be totally objective and verifiable since it’s based on real world, measurable criteria. I think it would work well in the United States if not other places.

As to the question posed by the title of discussion, no. At least not for trail_visiblity since it’s to subjective for even a local consensus. Let alone a regional or global one. So trying to strive for is clearly a waste of time. For trail difficulty though? sure. But only if it’s based on a nationally usable tagging scheme that’s based on objective, measurable criteria like the Sierra Club’s hiking classification system. Otherwise, any system based purely on regional or local standards would be less then useless. More so if it’s purely down to the personal preferences of the mapper at the time. Which something like “a trail that is X miles long and has an elevation increase of Y feet is classified as a Z grade” wouldn’t be.

I would find it problematic if the tagging scale ended before it reaches minimal effort (flat perfect surface path).

As someone who works with routing customers on foot (that would not want to go hiking) I would optimally want a scaling of OSM walkable surfaces that starts at one end with flat perfect paving walkways and ends with extreme mountaineering, with a clear divide when the walkable way stops being a “man_made” footway/path and turns into “natural”.

I’m not into this type of stuff a lot, but I would imagine creating a scaffolding scale of say 1-10 where 1 is minimum difficulty and 10 maximum, and then try to map all regional and national scales onto it as best you could - and eventually you’ll end up with something unified and namable.

Anyway, I’m cheering for your effort. Best of luck :v:


There was a bit use of dav_scale, but it never took off, five years ago perhaps latest addition. Bonus, you can read it off the guidepost. Malus, DAV and OEAV alpine clubs do not publish the grading scheme. Expect small scale regional differences too, eg. Salzburg vs. Tirol.

Be warned: Any formal proposal for global difficulty rating to will meet fierce rejection by a number of community members for whom sac_scale is the holy grail that all of the world has to nip from.

For fun, Way History: ‪Düsseldorfer Weg‬ (‪50923181‬) | OpenStreetMap - one of dav or sac scale must be wrong. Nice pictures here Kemptner Hütte - Düsseldorfer Weg - Marchscharte - Hermann-von-Barth-Hütte - Wandern show it DAV Black on the Austrian guidepost. Someone may have misinterpreted the guidepost on the German side. SAC T4 might do as well, but what do I know?

At least in America “mountaineering” isn’t really a thing. Let alone extreme mountaineering because we just don’t have places like the alps here. Nor really the type of homogeneous, well defined mountaineer community that exists in Europe. That’s also way we don’t have anything close to a difficulty rating system even close to sac scales. I dare to imagine what systems, if any, exist in the global south (or whatever for your prefered term for it is). Regardless, it’s a very Eurocentric way of looking at and trying to solve the problem. I imagine for any grading system to be widely adopted it has to be extremely simple and account for non-European hikers. Otherwise it will be bound to fail like sac scale and other aimilar systems already have. I’m not sure how a ten point system where most of the upper values only apply to 1% of the trails in the world would be any different.

If it were me personally I’d just leave mountainering completely out of it since you have to be an expert in the field of hiking and the area to do it in the first place and focus on the 99% of other users who are doing “regular” hiking. It’s like there can’t be a tagging scheme specific to mountaineering either. There kind of already is since they seem to be the main users of it. Otherwise, its just to big of a net and the fish are to small to catch any. You have to clear target audience in mind either way though for the tagging scheme to work well though and unfortunately “hikers” is just to general. Although mainly focusing on European hikers isn’t any better.

That is real concern that should be addressed if possible. (it may turn out to not be possible, though)
Do you have simple yet concrete suggestion how to improve such situation? (I’ve tried to follow, but I might have missed it - note that by “improve” I mean the solution which would be better than the current one, not just one that is differently biased)

[citation needed]? It does not look to me like sac_scale=* has failed, to the the contrary. Now, it may not be fit for your purpose or map to your area greatly, which is OK. Not ideal certainly, but not a catastrophe either.

Neither is cycling on highway=cycleway in Amsterdam anything similar to cycling on highway=cycleway in Zagreb. Yet people still use highway=cycleway for both, and for good reasons. If such reasons don’t work for your case, then don’t use highway=cycleway in that case (or sac_scale=* or whatever).

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Not specifically. I know that at least with sac scale 3 out of the 6 options are only or mainly useful to European alpine hikers, which kind of pigeon holes people from everywhere else since they only have 3 possible options. So maybe just don’t create a tagging scheme where half of the choices are restricted to an environment that’s only located in one part of the world. I’d also stay away from using any non-culturally neutral terms in the tag scheme and descriptions. One example being “mountaineering” which isn’t a term used by most of the word. Same goes for “alpine”, but to a lesser degree. Another related example is the “visibility” in “trail_visiblity.” It might seem super pedantic (and it probably is) but it’s a term that is kind of exclusionary to people with vision people. Not that I think it’s a big issue, but things like that can matter.

I was just looking at the usage and the top three sac scale tags were mostly confided to Europe and a small part of the United States. Considering there’s only 6 options I’d call that a failure. At least globally. It’s fine for a niche local tagging scheme, but I think we should get away from treating Europe (and to a lesser degree the United States) like they are the main or only places in the world. I don’t think you call a tag a success if it’s only or mainly a thing Germany, Austria, and those are the only places where half the keys are usable. I think that’s reflected in how many discussions and alternative tags there have been over the years to.

There’s really no good reason why there can’t be just one main tagging scheme for hiking that can be used in most cases. Just the fragmentation, consternation, conversations, Etc. Etc. are an indicator that it’s failure. Same goes for the other tags like trail_visiblity to BTW, but to a lesser degree because I don’t think the other tags are so propped up or pushed so hard as the alternatives. Sac scale people act like it’s the be all end all to trail mapping, which it clearly isn’t. Maybe that’s just me though :man_shrugging:

“Mountaineering” is practiced around the world. It is certainly a very niche activity limited to specific regions where large mountains exist, but these are found on most continents. The claim that mountaineering is Eurocentric is simply false. It is however limited to the class of people wealthy enough to afford the necessary gear, travel expenses, and free time.


Erm… :slight_smile:

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Alaska doesn’t count :wink:

Anyway, I said it isn’t “really” a thing, not that it doesn’t exist in the United States. It’s pretty easy to find an edge case to confirm whatever you want. That’s why I try and caveat a lot of what I say with “at least from what I know”, "the last time I checked, “it isn’t really”, Etc. Etc. because of course nothing is 100% absolute and people are always going to find one extremely rare example to try and undermine my point with. Regardless, mountaineering “isn’t really” a thing in the United States (sorry to any Alaskans who are reading this, but it just isn’t :man_shrugging:)

Ok, so by “isn’t really a thing” you just mean it’s a rare, niche activity that most people don’t do. This is very true, but it is true everywhere in the world. Most of the world isn’t made up of high mountains, and most of Europe isn’t either. However, mountaineering destinations exist all over the world, including the western contiguous United States. The claim that mountaineering is euro-centric don’t hold water.


Just to chuck in an example, there’s a fair bit of sac_scale usage between Kyburz and South Lake Tahoe. For comparison the PCT route is here. It’s not the Himalayas around here, but there absolutely are places where a bit of guidance about “what sort of path this is” would be useful.

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Essentially. I have no problem with saying mountaineering occurs in the United States. I use to have a couple of friends who hiked the area of South Lake Tahoe that @SomeoneElse brought up and southern Oregon who I’d probably consider mountaineers because they did a lot of their hiking in the higher elevations during the winter, which I’ve done a lot of in the same myself to.

The question isn’t really are there mountaineers in any given place. The question is are they enough of a demographic to justify creating a whole tagging scheme around and in a way that puts out “normal” hikers. I’d say no. If you want an example of that look at the options for sac scale. 3 out of six of them are only usable alpine hikers and are mainly used in Europe and the west coast of the United States. Most conversations on here related to hiking essentially revolve around them to. Yet at the end of the day they make up what, like 2% of hikers in the world?

You can say the claim that mountaineering is euro-centric doesn’t hold water all you want, but every time these conversations come up it’s mainly Europeans trying to dictate the conversation, posting the most messages, talking about European mountains, and most of the usage of sac_scale is in Europe. I could literally care less if there happens to be a small contingency of Saudi Arabians who like to take summer hikes in the Andes. They aren’t part of the discussions, they don’t do the tagging, they had nothing to do with defining how sac_scale or trail_visiblity are used, no one asks what their opinions are about it, add nauseum. It’s always Europeans doing those things. With a small contingency of people from the United States, who mostly just tow the line or get edge out of the discussion if they don’t like I mostly have been, but that doesn’t change the nature of the thing. The whole discourse around the scramble proposal was a good example of that BTW. 99% of it was discussion between Europeans about high altitude alpine hiking that no one outside of that little niche cares about and when anyone tried to discuss more ground level, “normal” examples they were mostly ignored and edged out of the conversation.

Agreed. There are far more trails for hiking, walking, strolling, rambling etc in the world than there are for mountaineering. An ideal difficulty or visibility scale would cover the lower end of trails that most people typically use much better than current tagging options do.

Yes, most OSM tagging conversations are dominated by Europeans. Evidence that OSM is euro-centric. Doesn’t mean mountaineering is though.