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

[erutan]

@osmuser63783

I’d like to understand better why the scale is supposed to be Eurocentric. The name of the key and values certainly are, but we can ignore that for a moment and pretend it’s just hiking_difficulty=T1, T2, etc.

That’s what I’ve been doing, and while it is intended for alpine environments I find it useful in other ones (sandstone rock in the US southwest etc). I personally think the bones of it can be adapted into a good system (or systems) but at the point where large parts of the text need to be ignored that IMO is an issue.

@osmuser63783

For example, I see no reason we shouldn’t tag a cliff path as T2 (“mountain_hiking”) even if there isn’t a mountain in sight.

So that would be ignoring the trail and requirements section, and solely focusing on terrain.

In general it’s not clear which majority of the aspects are ignored, and which single one is being prioritized. In an area where sac_scale is actually used perhaps these would be clearer to guess, but honestly I would have no real idea what to expect from T2 terrain. It could be any combination of the following:

• a trail with a steady ascent
• trail that is uneven enough to require sure-footedness and good footwear
• a trail that has some “fall hazards”
• a trail that requires some navigation skills (but ignore that part)

IMO an unexposed trail with a smooth path shouldn’t be T2 just because it has a steady ascent. That’s kind of goofy IMO, and we can generally get elevation gain metrics etc from mapping clients these days anyways.

As someone who has never hiked on a sac rated trail, I’m not sure how they interpret the differences in exposure between T2 " may pose fall hazards", T3 “Portions of the route exposed with danger of falling”, T4 “Terrain already quite exposed”, T5 “Exposed”, and T6 “Severe exposure”.

T6 I would take to be knife-edge exposure, sheer drops with a path a foot wide at most. T5 and T4 I’m not sure of “quite exposed” I guess is more indirect, some ledges below you or something, or a steep slope you could possibly self-arrest on. T5 would be, in between the two? T3 feels more like “this trail may spook you but you’d have to kind of try to fall off of it”, T2 is you might trip and fall or lose your balance on a piece of talus. Can some European users comment on this take?

I would argue that “fall hazards” probably means that you could “take a fall” walking on an uneven surface (judging by the sample photo on the wiki and escalation that mentions falling and exposure later) and not exposure, and that trail would be T3 “Portions of the route exposed with danger of falling” despite looking like a nice smooth single track trail.

I feel CAI T & E do a better job than SAC T1 & T2 for less demanding trails.

@osmuser63783

When exposure is bad but the walking is easy, or the other way around, then in my view we need to classify it as the higher of the two: someone who is only comfortable up to T2 certainly won’t want to walk this path.

That’s not going to be how non scramblers / mountaineers will think about ratings though. At the very least the wiki page should make this clear - that a T4 route can refer to either T4 levels of exposure or T4 levels of difficulty.

Having a smooth single track trail be marked T3 because it is near a cliff-edge is going to confuse people, there’s going to be an expectation of rougher terrain.

Comfort with those two don’t always go hand in hand. My partner enjoys unexposed T5 technique level terrain when hiking, but doesn’t enjoy fatally exposed T2 terrain. In my own shorthand adaptation of YDS and the risk movie rating criteria for class 5, I’m generally comfortable with 4 PG, 3 R, and 2 X when out hiking.

@osmuser63783

I try to tag paths I hike with smoothness, imagining what it would be like to ride my bike on them. wheelchair=yes is another tag I have found useful. (If it’s fine for a wheelchair it’s also fine for a pram)

Imagining riding a bike on them seems like a reasonable way of approaching it, and I agree that using wheelchair=yes on highly developed trails that are accessible is a good thing to do! Smoothness only covers T1-2 terrain though using YDS it’s all variations of Class 1. I suppose anything beyond that level of smoothness would be assumed to be SAC T3, but this is getting into “read between the lines and ignore 95% of the description and values and then adapt it to a subsection of another key and figure that out yourself” which isn’t really a reasonable ask of the average person wanting to help rate a path.

@osmuser63783

The fact that the smoothness page says the key is for vehicles (which includes bicycles) and then uses roller blades (which aren’t vehicles) as an example is one of the countless ways the Wiki contradicts itself. I would suggest changing the phrasing to “movement on wheels” or something like that, but I’m worried that would also lead to a long discussion thread.

Rollerblades are at least a wheeled mode of transportation made to be used on roads made for vehicles, I feel fine giving that one a pass.

[erutan]

@F_Weinmann

Definitly. What I want to say is that I feel that having them in the same category as this doesn’t feel right to me. Wide gravel ways shouldn’t be in the same value as semi-overgrown ground single-trails, unless our focus is heavily on the atleast semi-experienced alpine community.

If we want any hiking-tag to be valuable to the casual user, sac_scale T1 is too broad.

+1

A more reasonable trail_visibility where excellent wasn’t the only value that had a contiguous path (lolwut) would allow for this, and this is a point that @Hungerburg has been rightly insistent on making.

If there was an excellent that roughly mirrored the NFS Class 4-5 specifications for visibility, then good was along the lines of NFS Class 3, with 2/1 inspiring a poor and bad or something I think it’d be more useful and approachable rather than the current system in which 2/3 of the values are for some level of pathless terrain. I feel trail_visibility is more broken than sac_scale.

At this point it’s a busted system with a lot of use which makes it hard to change in any meaningful manner, and IMO there is a regional subjectivity to path visibility, creation, and construction that doesn’t exist with just movement over terrain (I agree with @osmuser63783 in this, just not that sac_scale does it well enough for a general casual hiking population). Having some new subsets of trail_visibility that use the old one as a fallback would make sense. Australia probably has different standards for trail visibility given people are used to walking through the bush than the US or Europe etc - if the Swiss are fine with sac_scale based visibility, that’s great they can keep using it as the first if before the else.

[tgdbepe4 (Peter Berger)]

The problem with the full planet is that my small test site has not enough CPU power and RAM memory.

You can see on the attached screenshot that sac_scale is used word wide:

Peter

[erutan]

I just asked my partner (who like me spends a lot of time in the wilderness, alpine or otherwise, but comes from a different background of leading wilderness trips in the NE US and Montana). She wasn’t happy with the options, but chose T3 unprompted. If we’re confused or doing it wrong, I imagine a lot of people outside Europe will be confused and doing it wrong!

That cliff trail isn’t a great example of what a T3 trail is supposed to be, and having it tagged as T3 is going to mess with more “true” T3 trails.

Edited out two line about lunch from an existing conversation before I asked this.

I edited this into the post above so it might get lost for people that read email updates, but is relevant here:

As someone who has never hiked on a sac rated trail, I’m not sure how they interpret the differences in exposure between T2 " may pose fall hazards", T3 “Portions of the route exposed with danger of falling”, T4 “Terrain already quite exposed”, T5 “Exposed”, and T6 “Severe exposure”.

T6 I would take to be knife-edge exposure, sheer drops with a path a foot wide at most. T5 and T4 I’m not sure of “quite exposed”. I guess it is more indirect, some ledges below you or a steep slope you could possibly self-arrest on. T5 would be, in between the two? T3 feels more like “this trail may spook you but you’d have to kind of try to fall off of it”, T2 is you might trip and fall or lose your balance on a piece of talus. Can some European users comment on this take?

[erutan]

@tgdbepe4

The problem with the full planet is that my small test site has not enough CPU power and RAM memory.

You can see on the attached screenshot that sac_scale is used word wide:

It used worldwide on OSM because it’s the only option for trail difficulty.

It is not used in the United States on the ground as far as I know. If it is I’ve not encountered it in multiple states, national parks, state parks, informal trails, frontcountry hikes, backcountry hikes, peak bagging, off-trail passes, mountaineering beta, etc over years of trail time. I’ve never had it come up in discussions with mountaineers / scramblers when talking about routes, on major off-trail discussion boards, etc.

My first exposure to sac_scale was from OSM, and that’s the only time I use it. I imagine there’s a significant amount of people worldwide for whom that is the case.

[erutan]

Here’s a proposed key for the terrain aspect of things. I don’t think it’s perfect, and expect it to be changed from constructive feedback, but I feel it’s more understandable and verifiable than what exists.

RFC: hiking_technique key (or a better name!) to describe movement on paths by hikers

Overview Most mapping clients can show the total elevation gain and distance, and some outdoors focused ones will even show details about the grade. These values can also be inferred by looking at the topo map itself, or the incline key if present. To me “difficulty” doesn’t need to include the basic metrics of a hike, but rather the terrain present and the way it is moved over. The former can have many aspects to it, the latter can be broken down into 3-4 major categories that are useful to de…

[SomeoneElse (Andy Townsend)]

@erutan

It used worldwide on OSM because it’s the only option for trail difficulty.

That’s probably true (although as I suggested above, other tags such as surface etc. would also help people understand how difficult trails might be). Usage of sac_scale in North America can be found at https://taginfo.geofabrik.de/north-america/keys/sac_scale#values, and within the USA at https://taginfo.geofabrik.de/north-america/us/keys/sac_scale#values.

[erutan]

@SomeoneElse

That’s probably true (although as I suggested above, other tags such as surface etc. would also help people understand how difficult trails might be).

Surface really needs to be multi value with expanded values to be meaningful in terms of difficulty unless people are creating new ways every time the surface of a trail changes. Outside of paved and maybe gravel it doesn’t say much about difficulty IMO. Even naturally occurring gravel can be loose and somewhat treacherous, or at least tedious. Multiple people have said to use compacted for nice single track trails to differentiate from just dirt which is looser, but that would indicate it being in between pavement and gravel.

Would a smoothness=very_horrible surface=rock be many 8.5" rocks or one large slab that is uneven up to 9 inches? There’s 7 values for smoothness up to 9 inches (which honestly isn’t that high in terms of the unevenness that can exist on hiking paths), and one value after which is impassable. Would impassable be rocks in a streambed you can hop around on, talus you need to use your hands for balance on, or a rock face that you need to scramble up? In theory you can make guesses based on sac_scale, but sac_scale isn’t used consistently in terms of the surface and can be referencing path existence, angle, or exposure instead - case in point the nice dirt single track that would be T3 up above.

That’s a lot of granularity and interconnected keys that were meant for non-wilderness use to an ambiguous end result. Heck surface has grass_paver as an unpaved surface.

[SomeoneElse (Andy Townsend)]

@erutan

Heck surface has grass_paver as an unpaved surface.

I’m sorry - I’m trying to be helpful here.

Yes, people who map stuff face the challenge of “how often should I change the surface tag”, but an approximation of surface information is better than none at all.

Perhaps the next time you’re out in the wilds keep a note of the tagging challenges you faced and write it up as an OSM diary entry?

[Hungerburg (Asa Hundert)]

@osmuser63783

The German Alpine Club has a comparison of German, Austrian and Swiss scales that I found helpful when learning about sac_scale. Maybe we should do the same with more scales from outside Europe and put it on the Wiki, to help people “translate” values from a scale they know

Let’s compare apples and oranges! Both shaped ball-like. They are the same!

[Hungerburg (Asa Hundert)]

@F_Weinmann

This is also T1, arguably even stuff like this is T1, both of which are far away from the T1 pictures in Wikipedia

There is also this picture, I repost here for your convenience:

Original source File:SAC SCALE T1.jpg - OpenStreetMap Wiki

It shows a mountaineer hiking an approach path. The photographer certainly is knowledgeable about the SAC scale (mind the CAPS). I’d see a USDA NFS class three trail. This might be the low anchor of hiking.

In the first mapillary picture, I do not see a path at all, the path in the second picture looks “steeper” than the T1 one above and less developed. Though I guess I’d have no problem going up or down there on my trekking _not: mountain bike, nevertheless, mountain_hiking might be justified by some, but up for debate by others.

[Hungerburg (Asa Hundert)]

@erutan

Technically T2 cannot be used on a trail without a steady ascent, is steep, and has fall hazards, regardless of what the actual requirement of “Some sure footedness” required.

Continental European interpretation was called for, so I answer: The Konjunktion (conjunction, obsolete according to wiktionary) is “or” rather than “and” or “regardless”

PS: “sure footedness” I know from places, where falls might be fatal or cause severe injury, but it also might be signed on places, where tripping can bruise your nose only, which is about anywhere, but to indicate a higher likelihood perhaps, due to rough surface?

PPS: These “Trittsicherheit erforderlich” (“sure-footedness afforded”) signs were found to not hold judicial deliberation, because they miss out the specificity required for warnings posted alongside of ways.

[Adamant1]

@erutan

Surface really needs to be multi value with expanded values to be meaningful in terms of difficulty unless people are creating new ways every time the surface of a trail changes.

Realistically how often does the surface of trail actually change though? I can’t imagine it happens anymore than with roads and we seem to get along despite it. Regardless, most semi-rugged trails are going to be dirt, closer to civilization they will be gravel, and then cement once you get into town. It’s not like there’s back country hiking trails that are dirt, but intermediately turn into asphalt or gravel for no reason and then change back into dirt again every half a mile.

That’s not to say there aren’t gravel or cement trails in outdoor areas, but at least in my experience they are branched off of main areas were the road or parking lot is already that surface. Plus it’s consistently the same until it changes to something else and mostly stays as that surface for the rest of the trail.

[erutan]

@SomeoneElse

I’m sorry - I’m trying to be helpful here.

Yes, people who map stuff face the challenge of “how often should I change the surface tag”, but an approximation of surface information is better than none at all.

Perhaps the next time you’re out in the wilds keep a note of the tagging challenges you faced and write it up as an OSM diary entry?

Well you’re trying to argue against proposed solutions with the status quo, but don’t really defend it. “You should just use these existing tags instead, they are totally adequate” > “This is how they’re inadequate” > “I’ll pick a clearly throwaway line and just say it’s difficult”. I’ve given some pretty clear examples where the ambiguity of SAC causes confusion, how the values of smoothness aren’t geared for hiking paths, and how surface often fails. If those are true, then it seems like some solutions would be in order (or we’re all just fine with how it is).

I’m not sure that partial information is better than none, it can lead to false assumptions. If a path is labeled as surface rock, but someone has joint issues and they don’t like all the flexing that happens on sand they’ll be disappointed when the path has sand in it. I usually don’t bother with a surface tag because I’d either have to make a way into dozens of segments or I’d just have to pick whatever seemed the most prominent.

@Hungerburg

Continental European interpretation was called for, so I answer: The Konjunktion (conjunction, obsolete according to wiktionary) is “or” rather than “and” or “regardless”

The end of that sentence is a typo - it’s smoky here and I have a headache so when I copy and paste things around or decide to change a sentence sometimes bits and pieces get left behind. ^^

@Hungerburg

PS: “sure footedness” I know from places, where falls might be fatal or cause severe injury, but it also might be signed on places, where tripping can bruise your nose only, which is about anywhere, but to indicate a higher likelihood perhaps, due to rough surface?

Was my take on SAC exposure more or less correct? You should be surefooted to avoid dying and to avoid bruising your nose, both aren’t great outcomes. T2 seems more like the “nose bruising” given it’s “a fall hazard” and the sample photo just shows someone walking along the shoreline of a lake. If T2 is fatal / need to rescued from a fall exposure then I’m not sure where T3-T6 go up from there heh.

[erutan]

@Adamant1

Realistically how often does the surface of trail actually change though? I can’t imagine it happens anymore than with roads and we seem to get along despite it. Regardless, most semi-rugged trails are going to be dirt, closer to civilization they will be gravel, and then cement once you get into town. It’s not like there’s back country hiking trails that are dirt, but intermediately turn into asphalt or gravel for no reason and then change back into dirt again every half a mile.

I’d say the majority of trails I’ve been on recently have changed surface. Trails in needles generally start off as dirt, go into sandy washes, climb over some broken boulders, go onto a slick rock ridge, drop back down again etc. One or two short ones that lead to other trails are just dirt, but even some typical “park and hike 2 miles ones” shift from dirt to rock multiple times. Some very common dayhike trails in Yosemite go through multiple surfaces - the trail to Glen Aulin can shift from granite slab to sand to dirt every couple hundred of feet, the mist trail up to LYV goes from pavement to rocks to dirt to rocks to dirt to sand to dirt etc. These aren’t extreme examples, but ones that are pretty similar to other ones I know.

Trails below the sub-alpine in forest tend to be more uniformly dirt if in wilderness, gravel or paved if near a road, but even in the northeast you’ll often have sections of them on bedrock at low elevations (below 1000 feet). I can think of a couple casual popular trails near family in upstate NY that have this happen.

[Adamant1]

@erutan

the trail to Glen Aulin can shift from granite slab to sand to dirt every couple hundred of feet, the mist trail up to LYV goes from pavement to rocks to dirt to rocks to dirt to sand to dirt etc. These aren’t extreme examples, but ones that are pretty similar to other ones I know.

I feel like there wouldn’t be an accurate way to tag how difficult the trail is in cases those anyway. So why not just go with surface as a best guess based on what type of surface expect to be there or which ever is the hardest to hike on, like just tag the rock/dirt/sand trail as surface=rock since it’s 80% correct and leave it at that. Maybe that’s just me, but I have to assume that anyone who is hiking a granite slab trail in Yosemite probably isn’t going to have difficulty with or care about parts of the trail that are dirt. Sands probably a different scenario, but whatever. I guess you do make a valid point against using the surface tag though.

[Hungerburg (Asa Hundert)]

Personally, I’d link “sure_footedness” with “head for heights”, but that is just my take on the subject.

BTW: Never trust third party accounts, the summit post you linked above pretends to verbatim copying SAC documents, where they just give their own account. Where they say, “path marked to the brim” the original says “When marked, then this colour.”

[erutan]

@Adamant1

I feel like there wouldn’t be an accurate way to tag how difficult the trail is in cases those anyway. […] Maybe that’s just me, but I have to assume that anyone who is hiking a granite slab trail in Yosemite probably isn’t going to have difficulty with or care about parts of the trail that are dirt. Sands probably a different scenario, but whatever. I guess you do make a valid point against using the surface tag though.

The Glen Aulin trail is mostly T1 / simple walking difficulty despite going over various surfaces - the dirt is nice single track, the parts where it goes over granite slab are low angle (and the slab is grippy while being relatively even), and the sandy bits are a bit annoying but tend to be short and not impactful. There might be some areas where there are enough roots or rocks on the dirt parts to count as T2 / complex walking, but those obstacles in the surface are more impactful than what the surface actually is. That can kind of sort of be covered by smoothness, but I feel like use of that tag for non wheeled traffic is going to be all over the place.

This isn’t from that trail, but it’s just across it on the other side of the Tuolumne River. It gives a good idea of how difficult it is despite not being a dirt surface. Surface=rock isn’t always scary! (to clarify the path would be equivalent to walking horizontally near the bottom of the photo)

@Adamant1

So why not just go with surface as a best guess based on what type of surface expect to be there or which ever is the hardest to hike on, like just tag the rock/dirt/sand trail as surface=rock since it’s 80% correct and leave it at that.

I have thought about just tagging trails with the most common part, but even that has issues. The Lost Canyon lop trail in Needles is mostly dirt single track, some sand when it’s near a river bank, but the middle of it jumps in both technique and surface (T1 movement up to T2/3 with some exposure, though the T3 exposure is where the movement is T2). In that case I think it’s probably worth breaking the middle part into it’s own segment as there’s a significant enough difference, but just changing it to surface=rock* doesn’t really indicate that it requires more technique, heck once on top of the ridge it’s basically T1 until you need to drop again.

It’d be nice if surface was multivalue for areas where it doesn’t really impact difficulty but still sort of tells a story: surface=rock+dirt+sand or something. I think that’s more accurate and useful vs just picking one, and more realistic and easy to parse vs creating a new way every time it changes.

[erutan]

@Hungerburg

Personally, I’d link “sure_footedness” with “head for heights”, but that is just my take on the subject.

I think you can need to be surefooted on unexposed terrain (say hopping along talus or boulders on a dry stream bed). I’d rate that as PG.

surefooted and with a head for heights / composure would be more R - X exposure. I just whipped up this real quick to go with my previous hiking_technique key. I had it mostly written for another project and just had to swap some phrasing around.

At some point soon I’ll try and get a us_trail_visibilty and then the three can be put together and see how effective / accurate they’d probably be,

[bradrh]

@erutan

It’d be nice if surface was multivalue for areas where it doesn’t really impact difficulty but still sort of tells a story: surface=rock+dirt+sand or something.

I just use surface=ground for varied surface. Part of the problem with these tags like surface & trail_visibility is there are too many options.