RfC Part 3: foot_scale=* (aims to describe global paths in a more helpful and informative scale than SAC)

Ideally should YDS 4 / SAC T5-6 semi-technical terrain be in highway=path?

  • Yes
  • No
0 voters

Given this is current practice, we’d need some solution - either a new highway type, moving such content into climbing=*, or something else.

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Is using demanding|difficult alpine hiking values for highway=path currently valid/proper in OSM?

  • Yes
  • No
  • Unsure
0 voters

Asserting that something either is or is not “technically/formally correct” in OSM is nearly impossible. The closest we can get is to say that there is or is not a general consensus about how said thing should be mapped. In this case we do not seem to have consensus. Many mappers feel that YDS 4 / SAC T5-6 semi-technial terrrain should not be mapped as as highway=path (including me), but many others feel strongly that it should be.


I’m going off of the wiki for simplicities sake. If someone tried applying sac_scale to a major highway or tagged a mountain stream as a convenience store it’d be considered incorrect

highway=path lists demanding|difficult alpine hiking as valid values, sac_scale says it is for highway=path|track|footway, etc.

How would someone new coming into the community know that demanding|difficult alpine hiking isn’t supposed to be used on highway=path (or at least that there isn’t a consensus)? Not counting wading through these threads :slight_smile:

My impression is that OSM documentation is built around T5 and T6 are valid values for highway=path, but there’s controversy/disagreement about it.

IMO if we’re going to cap foot_scale at T4 / YDS 3, then ideally we need some plan for the values above it. I don’t see a way without altering major commonly used keys as well - that doesn’t mean it shouldn’t be done, but it adds complexity.

highway=technical_scamble doesn’t quite feel right to me given the overlap with climbing=*. Is a UIAA II route under climbing=*, but a T6 route under highway=technical_scramble even though they’re interchangeable if you’re talking about rock?

If we have it, why not a highway=simple_scramble too? (or just try again with highway=scramble and have two value scramble scale, and then local scales on top of that, which feels… messy). I can think of trails on the east coast that involve some scrambling, but are still very clearly paths.

UPDATE: I EDITED THE WORDING ON THE QUESTION. Perhaps this makes it less loaded?

Glacial travel is something this scale doesn’t really do well at (or at all). As an American that hasn’t done a lot of backpacking in the few ranges here that have a lot of glacial travel it’s not something I really considered.

I assume this route in the North Cascades in WA (deep cut for a previous out of control thread last year lol) would be YDS 2, but SAC T5.

I feel like the number of people who are going to dig into the surface=* of a path are pretty small. I guess a renderer could detect the surface and SAC level and come up with a way to render some warning about crampons, but we fall back into SAC not being well known outside of Europe (and glaciers occur worldwide).

I still like the idea of expanding hazards, they’re more specific and useful. A value that is essentially “crampons and ice axe needed” ala Secor is a lot clearer than someone seeing T5, looking up surface, checking that T5 path is only for ice and not rock so it refers to that section and not another, etc.

I personally feel once you’re past foot_scale=simple_scramble you shouldn’t be relying on OSM to safely do a path/route, it’s worth looking it up in some more long form way elsewhere more suited to more technical / nuanced terrain. It is useful to know that it’s difficult enough that doing so is a good idea though!

Looking at the photo above: If You need crampons there, then it is not T4, because T4 specifies trekking boots good enough. For You, this then would be T5. I can imagine walking there with sneakers, attentive for sure; Certainly, for Me, the choice of footwear alone would not make it T1 :wink:

There might be a US / non hardcore EU centric bias of votes here or something but there seems to be a strong majority thinking YDS 4+ and SAC T5+ shouldn’t be in paths, and a less certain ambiguous feeling that OSM currently allows this.

  • Move YDS 4 and SAC T5-6 (non-ice) into climbing=*
  • Create a new highway type for this specific terrain.
  • Have foot_scale include a YDS 4 / SAC T5-6 value with caveats
  • Just have foot_scale go up to YDS 3 / SAC T4 and leave higher grades ambiguous
  • Other (comment below)
0 voters

Beware there’s less than a handful of people voting or replying here…


I was going to mention the small sample size in the comment, but didn’t bother. I’m not sure how to get more input without making it a formal proposal, and generally once a formal proposal fails it isn’t seem as worthy of proposing again later.

I think I’ve come up with yet another better solution for the upper end of the scale. sighs hopefully

This probably won’t be ideal for hardcore alpinists, but we’re not the focus here.

What if value six is just something like requires_equipment? requires_tools?

Most terrain that is above simple scrambling recommends that (novices at least) use rope and helmet. Obviously there are people that can free climb El Capitan etc, but let’s say “non-specialists” or something. :slight_smile:

This also would cover any travel on a glacier that requires crampons, or paths that are so overgrown you’d need an axe or saw etc (this latter gets more into the spirit of @Hungerburg’s fork into walking_scale=not_walkable).

While some people (including me!) would consider walking on a mildly angled glacier with crampons easier than simple scrambling, if I didn’t have crampons that would be different. All terrain that requires equipment is, I think, a very good check for a casual person.

Having hazards that match up with this could be useful too - traction required, overgrown, deep pools for flotation, etc that could indicate the type of equipment required.

Local scales with more granularity over terrain that requires equipment will still exist, SAC etc. They can be tagged along with this value for more information for us technically minded folks.

Value 6: Requires Equipment

Editor description: These paths are not safely or comfortably passable by non-specialists without use of equipment.


Paths that fall into this would include:

  • Travel on a glacier or areas that hold ice that require ice axe and crampons.
  • More difficult “semi-technical” scrambling that overlaps into easier technical climbing (YDS 4 goes up to YDS ~5.5, SAC T-T6 goes up to UIAA I-II, BMC 2-3 recommend ropes and helmets).
  • Abandoned or infrequently maintained paths that are so overgrown to be impassible or near impassible without use of an axe or sawm.
  • Terrain where you could get stuck or need to swim, where having a flotation device, a winch, or swimming could be necessary.

There is often little to no sign of being a proper “path”, though it is a route that people have done before. Many countries don’t print semi-technical scrambling routes on maps, though such terrain may show up on informal paths.


  • Accessibility: You should have the proper equipment to safely traverse this path. Further research is necessary.
  • Focus: Loss of focus can have serious or fatal consequences.
  • Footwear: Something specifically designed for the rough terrain would be appropriate.

Roughly equivalent to local scales: Class 4 YDS, Bouldering VB, SAC T5-6, UAII 1-2, Austria “Alpine Route”, CAI EEA-EAI, AWTGS 6?, PWS T3-R?, BMC Grade 2-3.

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I just posted my vote. Mind you, I tried to establish such a new value in the highway key. In the process I learned: People found it extremely difficult to trust OSM mappers to decide, whether use of hands is necessary, therefore such a criterion cannot be used to tell apart a hands-free walkable path from a climbing route. Others found it extremely useful to have routes of national importance show in every map that is, and if such a new value would hide them, no-go, regardless of use-of-hands/equipment/you name it.

What about creating a new tag for highways requiring equipment instead of a sixth value? Something like requires_equipment=yes, or more detailed requires_equipment:crampons=yes, requires_equipment:rope=yes etc. It could be applied both for highway=path and for a new highway type for SAC T5+

This idea seems reasonable to me. If the terms “equipment” or “tools” are too broad and could be interpreted to include more common things like hiking boots, trekking poles, or a compass the value could be further qualified with something like *specialist_tools* or *special_equipment*. The idea being that ways with this foot scale value require some specialist equipment beyond the typical gear for an average day hike. People will probably quibble about what counts as special equipment, but this seems solvable with good documentation on the wiki. It might also vary a bit by region if some peice of equipment is considered totally normal and carried by everyone in one place, but is niche and only for specialists in another. That hypothetical can probably be set aside until/unless something concrete comes up.

More detailed optional keys specifying the type of equipment required are a good idea. The point of the sixth value though is just to indicate “this terrain is more difficult to traverse than the average path and requires special equipment and/or skills”. Some data consumers that aren’t interested in the nuances of backcountry terrain can just treat all ways tagged with this in the same manner indicating “beware, difficult/hazardous terrain” to their users. Other data consumers can take this sixth value as an indication to look for other tags that specify more detail.

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I know that you’re discussing specialised equipment required for rock climbing, ice etc, but I’ve seen Australian hiking tracks that are marked that you must carry a PLB, & that you must also carry 1l of water per person per day.

PLB could also come under “requires_equipment” but how about water?

Sorry for the long absence, I’ll aiming to link to a proper draft page of this with photos soon. :slight_smile:

I think having a sixth value is useful because it caps off the scale and provides utility at a glance - this is above what a normal untrained (able bodied etc) person can reasonably do. Agreed on some way of specifying what kind of equipment it requires.

This could also work with a hazards tag that isn’t just for vehicles - ice, exposed rock, deep pools, etc.

Yeah it seems like a reasonable way to cap things off, and doesn’t hit some of the issues of the previous “unwalkable” (hopping over a rock, ducking under a tree branch, trail running, etc). While obviously people can climb well above T6 without rope, your average person off the street shouldn’t be attempting it without protection (which is one reason via ferrata exists).

Yeah, ice axes will be very common in the Alps etc above a certain elevation. That’s still within a somewhat specialist mountaineering community though. I suppose in some tropical environments a machete or similar might be standard as well, but I agree that feels niche.

Yeah, I kept the word specialist in there for that reason.

A PLB doesn’t impact your ability to actually traverse the path. Carrying water is a pretty common thing to do, and most people have water bottles. 1L per person per day seems incredibly low. The Grand Canyon recommends 4L iirc, but obviously people can dayhike portions of those trails with far less or nothing.

There could be a hazard tag for something like “no water sources, excessive heat” etc.

This an a known route, the National Park Service issues overnight permits for it etc. There is effectively no path, but at least on this beach at this time it’d be casual. I suppose at a higher tide and up on softer sand with some rocks around it’d be attentive.

This isn’t really covered in foot_scale - generally speaking such invisible routes are getting into more technical terrain, but routes below high tide line are an interesting outlier.

I see, casual is breathing outdoor and perhaps a tiny bit of adventure too; And that is how I perceive of it just as well :slight_smile:

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I might need to reword casual - path width here doesn’t exist (though there’s obviously room to walk past someone or walk side by side etc).

I suppose pathless paths could be attentive just because you have to look where you’re going and do some routefinding, but then we’re getting into a weird overlap with visibility (which we both have issues with).

Depends on the tide…

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Yeah. I copied and pasted some conversation from elsewhere else related to this.

Also was able to troll both trail_visibility and sac_scale at the end so :partying_face:

Back to work now…