RfC: New Key foot_scale=* ("now for something a bit recreational")

This lifted from long discussion in this topic: Here rendition from top of my head, hope I am not too far off:

Key foot_scale values:

  • casual_walking : No obstacles on the ground, no need to lift legs; default on paved or alike even surfaces; a.k.a. strolling.
  • attentive_walking : Obstacles on the ground either conveniently avoided or easily stepped over, yet have to be looked out for to prevent tripping.
  • surefooted_walking : Rough ground all over, need to lift legs high, placing feet on uneven or overgrown surface wants skill and care.
  • impeded_walking : Roughness and unevenness of the terrain additionally invite casual placing of hands on rock, on vegetation, etc. to aid balance or clear passage.
  • not_walkable : Not traversable in a manner usually called walking; called crawling, scrambling, climbing, wading/swimming (through deep mud), struggling (through vegetation), &c. you name it!

Pictures (New!)

A gallery on the wiki to place photos selected from commons or comment on existing pictures

Personal observations:

The wording makes ascending or descending stairs calling for attentive_walking. I’d be fine with that. At lest the first and likely last step should be watched out for! Same goes for kerbs when crossing a street?

Further risks like spraining an ankle can be lessened with appropriate footwear. For the sake of this scale, casual footwear is considered the base.

Progession of the scale seems to make a jump between attentive and surefooted, an in-between value might help. Or maybe not, see below.

What about busy sidewalks, the number of people certainly makes a difference, does it?


This is intended to get mostly tagged on paths. The use of path is so broad and depends so much on evaluation of attributes of which there are many - so lets create another one :slight_smile:

Perhaps a smart consumer can condense a mix of existing keys like surface, smoothness, hazard, obstacle, sac_scale, mtb_difficulty, etc. into the values suggested here. For most purposes this attribute can do more in less: obstacle=rocks e.g. cannot set apart attentive_walking from surefooted_walking. All the while, other keys are not precluded by this one.

Relation to key sac_scale:

There is overlap. foot_scale and sac_scale can be applied together, they do not compete. Main selling point though: foot_scale does not need mountains or Alps. So chances are, it might prove useful and find application after all.

Relation to key obstacle:

Obstacle is a very good candidate for tags used in conjunction with, as it may hint at what prompted grading.

Please share thoughts and ideas!


Rather than an extra in-between, how about a new bottom level “strolling”, but still with the current “no obstacles etc” definition?

Then lift each of the others by one level i.e. casual = avoided or stepped over; attentive = lift legs, uneven surface; sure-footed = rough & uneven; replace impassable with impeded = not walkable.

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Thank You, I changed the intro a bit. Do I understand correctly, you suggest to drop impeded? I was kind of happy when I found the term, because it contains pedes – latin for feet – and the prefix im- which negates the term - so it highly on topic :slight_smile:

I think the 5 levels listed here are a good summary of where the discussion in the other thread ended up and are a clean rewording of the most stickiest points.

I don’t think that an additional level between attentive_walking and surefooted_walking is needed.

While I was a proponent of highway=scramble idea to get difficult ways out of highway=path completely, I see not_walkable as a nice option that could cover scrambles and other non-walking segments without having to identify precisely the mode of not-walking. Climbing through dense trees/shrubs or swimming through mud come to mind as additional ways to move along a path that aren’t steep rocky sections. Using this foot_scale=* tag can also be orthogonal to the highway=* tag and so be applied outside of highway=path. For example, highway=track (some 4WD trails might not be walkable for various reasons) or damaged highway=steps that require extra scrambling.


No, exactly the opposite! - use “impeded” instead of “impassable”, but with the current impassable definition.

For context, the most recent version proposed in the other thread can be found in this post. It is very similar but has more detailed descriptions, and a mapping to the values of others scales (e.g. SAC, YDS) that should probably be considered tentative (as a 1:1 translation won’t be possible or desirable).

My own attempt at summarising the rationale can be found here.

I think your post is a good summary of the previous discussion, with some minor changes.

It would be good to hear from as many people as possible what they think about it. Especially mappers from around the world, where the terrain might look rather different from the Swiss Alps. We could also make some posts in regional communities. I am also thinking that a gallery of examples from around the world could be helpful, a bit like this one for smoothness. Between us we can probably cover a lot of different terrain types.


If you plan to document this on the Wiki, it would be helpful to add example pictures to each scale.


The forum has no “perplexed” icon, I am a bit at at loss. While etymology of impeded literally might say not-walkable, the colloquial sense I read it more like delayed, hindered, but not impossible - another im- term.

The wording was chosen to be as short, so to show in editor presets.

Anybody fluent with wikimedia commons categories?

Found a few possible photos.

Post them here?

Something like this Key:smoothness/Gallery - OpenStreetMap Wiki (been shared already above.) In a temporary location, maybe even in a user page namespace, @osmuser63783 ?

Note that there’s been a lot of discussion around the naming of values 4 and 5 on the previously discussed forum. Impeded works for a value 4 label, certainly as good as anything with that amount of conciseness even it’s perhaps not as clear as some of the longer ones.

The major change would be dropping the scramble value from the wording below, and replacing it with not_walkable.

If we do only port over SAC T1-T3, then we need to come up with some way to have those values represented in OSM, as they’d be above this scale and below climbing=*. Here’s some thoughts on options:

  1. Some kind of scramble_grade:yds/bmc/sac=* would be my suggestion, to crib off of the existing climbing:grade:*=*.

  2. Another option would be to just have top level yds_scale and bmc_scale keys etc to live alongside sac_scale and be used regionally as appropriate.

  3. We could come up with a OSM based system scramble=* with values like casual, semi-technical, etc but given there are many existing localized systems that tackle this area that people are familiar with, it doesn’t seem productive. foot_scale is useful because it focuses on casual terrain that technical folks don’t really think about, but 99%+ of the world’s paths fall into.

  4. sac_scale is still the global default for terrain between foot_scale=* and climbing=*, concerning itself with T4 to T6 globally and the full range in countries where it’s commonly used and known. This doesn’t feel good to me.

IMO this needs to be addressed vs skipped over.

As @osmuser63783 mentioned above, there’s a more detailed draft above. (RFC: hiking_technique key (or a better name!) to describe movement on paths by hikers - #68 by erutan).

Bringing in the wording for impeded_walking (which isn’t perfect, but is the best two word solution we’ve come across), I’ve updated the proposal in the previous thread with some of the discussions since.

Note that this includes a top grade of scrambling vs not_walkable - I’m not sold that it’s a necessary thing, but at some point those grades need a place to live. Just keeping T4 to T6 in sac_scale isn’t a great global solution IMO.

Shoving them all in a “here there be dragons but not quite technical climbing” made sense to me at the time. It could be used to describe the general scope of a scramble tag that then let’s people choose localized systems or some other solution.

Value 0: unverified walking


This value would exist for data ported over from the existing sac_scale T1, as the trail could be either casual walking or attentive walking and that would need to be done manually later.

Value 1: casual walking


Falls under: Class 1 YDS, ~NFS Class 4-5, SAC T1 / Yellow, Austria Blue, CAI T, AWTGS Grades 1, PWS W1 & W2

Obstacles: The ground may not be entirely smooth and have some irregularities, but it has few obstacles and they tend to be smaller or have a large amount of space around them. It isn’t uncommon for these trails to use imported materials for their surfaces, but can also be on compacted or naturally even ground.

Typical Experience:

  • Casual walking paths that are wheelchair accessible should be tagged with wheelchair=yes. In general people anyone that can walk but have minor mobility issues, need to use a walking aid, the very young and elderly, etc can safely traverse this terrain.
  • Almost all casual footwear will be adequate.
  • Little to no focus needed, people can walk and talk and not pay much attention to the path surface.

Value 2: attentive walking

Falls under: Class 1 YDS, ~NFS Class 2-3, SAC T1 / Yellow, Austria Blue, CAI T, AWTGS Grades 2, PWS W1 & W2


The trail has some ankle to knee high obstacles like roots or rocks, but these can almost always be walked around and it’s possible to walk on an even or nearly even surface. Anyone that can walk in a coordinated manner and avoid obstacles should be able to handle this terrain.

Typical Experience:

  • People that need to use aids when walking, or have some kind of issue that impacts their mobility can have problems in sections.
  • Sneakers or other casual footwear should be fine.
  • Focus occasionally needed, people can walk and talk at times but will need to look at their feet.

Value 3: surefooted walking


Falls under: Class 1 YDS, NFS Class 1-3, SAC T2 / White-Red-White, Austria Red, CAI E, AWTGS Grade 3?, PWS T1-T2

Obstacles: The path has around ankle to knee high obstacles (roots, rocks, etc) that need to be stepped on / passed through to proceed forward. It’s common to have long stretches of trail that are on uneven surfaces, where people need to be surefooted and be able to walk with balance, coordination, and sure-footedness.

Typical Experience:

  • Footwear is more consequential. Lightweight but outdoorsy shoes like trail runners or approach shoes would be helpful, but sneakers should still work though more care might need to be taken at times. People with bad ankles or that lack experience may want traditional mid or high top boots.
  • Attention will need to paid to footing for long stretches in places to avoid loss of traction or falling.
  • This can be very challenging to inexperienced hikers, but will be straightforward for mountaineers.

Value 4: impeded walking


Falls under: Class 2 YDS, NFS Class 1-2, SAC T3 / White-Red-White, UAII 1, Austria Black, SWW White-red-white, CAI EE, AWTGS 3-4?, PWS T3-T4?, BMC Grade 0.5?

Obstacles: This ground that is uneven or steep enough that it’d be reasonable to expect people to occasionally use their hands or trekking poles for balance while hiking. If talus isn’t so large you need to climb over it, but it’s larger than in surefooted_walking and you need to put a hand on a piece here or there to support yourself it falls into this category. You might be occasionally be pushing off or lightly pulling on obstacles, but you aren’t actually using them to scramble or climb.

Slope note: Even flat terrain can have obstacles on it that require use of hands to surmount. Additionally once terrain gets close to or over 30° hands (or trekking poles) are generally used for support and balance as the slope itself becomes an obstacle. Nearly all highly developed trails are explicitly designed to avoid such steep angles, but there are exceptions.

Typical Experience:

  • You need a stronger sense of balance and coordination than on surefooted_walking terrain. Being able to control your body’s momentum and be aware of your weight and how it is moving over obstacles is important.
  • Footwear with grippy soles meant for hiking is highly recommended (boots, approach shoes, etc). These can still be very lightweight for experiened individuals.
  • The ability to think a few steps ahead and a little bit of confidence when focusing on the path are very helpful. :slight_smile:

Value 5: scrambling


Falls under: Class 3-4 YDS, Bouldering VB, NFS Class 1, SAC T4-6, UAII 2, Austria “Alpine Route”, CAI EE, AWTGS 4-6?, PWS T3-R?, BMC Grade 1-3

Obstacles: High angle obstacles that need to be “climbed” for significant lengths of time finding handholds and footholds and pulling oneself up, but are simpler than technical climbing which use of a rope and harness are expected (see grading systems above). Feet are off the ground for more than a few moves, or there are repeated sections of short climbing. This is going to be a slim minority of paths in many regions.

Typical Experience:

  • You need to be able to pull up a decent portion your body weight with upper body strength.
  • Approach shoes, “high route shoes”, cross trainers, or boots are recommended. You’ll generally want either more traditional boots with “structure” or a lightweight shoe that conforms to the foot for better feel and independent use of foot muscles for control.
  • While not considered “technical climbing” significant risk can be involved. Previous climbing or mountaineering experience is highly recommended.

I created User:Hungerburg/FootScaleGallery - OpenStreetMap Wiki – please share them in the rsp column. Looking forward to learn what others grasp from the few words :slight_smile:

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Added images but they didn’t appear, so not sure what I’ve done wrong? :thinking:

It was the syntax, I’ve fixed it


I added a new row of examples related with obstacles caused by vegetation. We haven’t discussed much about those, but I guess they should be covered by the same scale. For convenience, I’ll repeat my attempted definitions:

  • casual_walking: Generally clear of vegetation, or covered by low, manicured grass
  • attentive_walking: Overgrown by low grass; occasional vine or side shrub invading the path
  • surefooted_walking: Overgrown by tall grass; needs careful walking to avoid vines or shrubs
  • impeded_walking: Overgrown in scrub, or impeded by tree branches; requires use of hands to unfold or cross the obstacles
  • not_walkable: Overgrown by dense, impenetrable vegetation or blocked by fallen trees

By the way, I’m in favor of the proposal, and I feel it covers a lot of ground which has not been covered so far. I would favor less wordy tag names though – they need explanation anyway, so why not use something better memorable? I’d prefer something like {easy; attentive; surefooted; difficult; unwalkable} for the five grades (perhaps we could add the zeroth value such as unspecified, but I don’t see how it would differ from sheer absence of a tag).

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They didn’t use to all end with walking back when, though I suppose that is redundant at this point.

Easy and difficult are problematic as values IMO as they tend to lead themselves to very subjective takes - most mountaineers would describe all terrain in this scale under unwalkable as easy. An elderly person or someone with mobility issues would likely find surefooted or even attentive walking difficult.

Impeded could be replaced with obstructed I suppose.

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Hmm, the walk is impeded, but the path is obstructed, am I right? So impeded is better IMO.

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Thank you very much for the fotos and descriptions. Thank you @Fizzie41 too. Myself living in a rambler/scrambler bubble might have posted quite different ones. So I am happy that you made the start.

foot_scale is purely pedestrian. The suffix _walking reminds of this. I rather not drop it. Redundancy can be of help to ascertain quality.

How about a post to the help topic: Call for Papers Pictures! How to reach out for more people?

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I posted a Call for Pictures to the tagging mailing list, [Tagging] Call for Pictures - no response 30 hours later. Is there any community interest apart from us three?