Implications of sac_scale=strolling

rhhs · 2024-12-01T09:24:49.666Z

What I mean to say is that so far, the other sac_scale values do not take steepness into account, only technical difficulty and exposure. Maybe we should keep it that way also for the new value, and accept that “strolling” should sometimes not be taken literally. sac_scale is then like “smoothness for pedestrians”: only the roughness of the surface should be taken into account.

Vinzenz_Mai · 2024-12-01T10:20:20.822Z

supsup:

In general I would say incline should be under 10 % or so.

I’ve got the same point of view. There should be a recommandation (not a hard value) for a maximum incline. I wouldn’t see a way with an incline of 15% as “strolling” anymore. 10% for small sections could be tolerable.

rhhs:

sac_scale is then like “smoothness for pedestrians”: only the roughness of the surface should be taken into account.

I don’t see it that way. It should be taken more literally than that. It should really be pathes that are really easy to use without much effort.

rhhs · 2024-12-01T11:27:44.937Z

Vinzenz_Mai:

without much effort

What matters here is the definition of “effort”. So far it has been the effort of feet (and sometimes hands, arms, etc.) to cross the terrain safely, without taking the effort to gain or loose altitude into account.

Hungerburg · 2024-12-01T23:45:46.259Z

Personally, I’d not fight against calling walking that section of St. James Way a stroll rather than a hike. Yet, I am neither a hiker nor a stroller; I myself can cope that modest incline decently. I just observe people walking, up or down.

BTW: I also observed sac_scale=demanding_mountain_hiking getting used above sac_scale=mountain_hiking to indicate steepness of paths in mappings, where I could not see any technical difficulties. But that is just what I observed in the past, way before openstreetmap decided to deviate from the source of what the tag originally wanted to convey and instead do its own thing. So yes, I think, steepness also played in back then.

rhhs · 2024-12-02T07:08:00.688Z

Hungerburg:

I also observed sac_scale=demanding_mountain_hiking getting used above sac_scale=mountain_hiking to indicate steepness of paths in mappings, where I could not see any technical difficulties.

I think that is a tagging mistake, and I would edit it to sac_scale=mountain_hiking if hands are not needed for balance.

It’s worse when someone maps a trail as sac_scale=hiking because there is no elevation change while it is actually hard-going. We hiked the Lycian Way in Turkey last weeks, and found long sections of coastal path that were quite hard (max. 2 km/h, constantly watching your footing) but were tagged as sac_scale=hiking. Some were as hard as this path A closer look at the rocky coastal path between Limanağzı and Boğazcık [503] [A4] – Trekopedia (which is correctly tagged with sac_scale=demanding_mountain_hiking).

supsup · 2024-12-02T12:25:17.912Z

Steepness of the terrain has always been a part of the specification. Sometimes these tags are used very unappropriately, using T5 for something that is T2-T3.

I do agree that steepness should not be a determining factor, I see it more as a circumstance. T4-T6 will rarely no be steep, unless you are traversing something very vertical horizontally.

Not sure how to go about it - I think the wiki is already well documented and that is how it should be done.

SomeoneElse · 2024-12-02T12:57:58.906Z

supsup:

Sometimes these tags are used very unappropriately, using T5 for something that is T2-T3.

Rather than saying something like that can you instead say “which OSM tags” and “which OSM values” are used inappropriately, and what they are used inappropriately for. If you say “T5” to most people, even in OSM, they’ll probably just think that it is a type of Volvo car.

supsup · 2024-12-02T13:01:09.638Z

demanding_alpine_hiking four mountain_hiking, wrongness probably (I do not know why people choose those values) due to steepnes. Never heard of such a Volvo car, I am happily almost oblivious about that abominable invention:-D.

Another source of confusion can be official designation. In Argentina, they use colours I think three or four, but the main distinction seems to be length and elevation difference, all the trails overed by it were mostly hikin or mountain_hiking. Somebody might have try to do 1 : 1 mapping to sac_scale, when at least two of their grades corresponded with one sac_scale grade.

Hungerburg · 2024-12-02T23:04:39.246Z

SomeoneElse:

Rather than saying something like that

I also think, the column “Equivalent SAC scale based on Swiss Alpine Club” should be removed from the fine article. Especially, if openstreetmap wants to emancipate. Any takers? I am tired of sentences like “But on hikr.org Großglockner is a T2”.

supsup · 2024-12-03T01:01:24.340Z

Well, there is still the mention that in Switzerland and that part of Austria where it is officially used, it should actualyl adhere to the official grades.

yvecai · 2024-12-03T10:42:24.988Z

Then let’s start to remove that: OSM is global, if a local community wants to have local definitions, they can specify it elsewhere. And in the present case, that’s almost stating the obvious and except for a handful of cases it will robably makes little harm.

rhhs · 2024-12-03T18:19:58.031Z

An example of a section I tagged as alpine hiking T4 because of “Use of hands needed in order to advance” that is without incline.

IMG_20241111_153134161_HDR1920×3412 864 KB

Did I tag that correctly?

supsup · 2024-12-03T18:35:10.629Z

I think this is ok. I would probably tend to put demanding_mountain_hiking because there is no exposure (and to anyone having sticks or even a branch, which I do not count as using hands, hands would not be necessary), but I can live with your classification too. Definitely not hiking or below!

Road_Runner · 2024-12-03T18:45:43.957Z

It’s clearly described in the wiki, that exposure is also a criteria for sac_scale. It is the combination of exposure and technical demands that make a trail “difficult”. And that is exactly what sac scale wants to describe.
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I would rate this route as T2 or T3 at most, it’s not a route in the sense of alpine hiking. Alpine hiking requires basic climbing skills and falls can be potentially fatal, that doesn’t seem to be the case here.
EDIT: But you could make a poll?

Road_Runner · 2024-12-03T18:53:57.613Z

Why should we remove it? It is just an abbreviation, also used by a lot of renderers like Tracestack. And also the relationship to the official sac_scale is already well described in the wiki.

Hungerburg · 2024-12-03T22:32:12.537Z

rhhs:

Did I tag that correctly?

This question is NP hard, in engineering speak. I have seen similar pictures on the SWW website for trails ranked T1 (SAC grading). No idea, who does the grading there, I guess not the people from the SAC working group tasked with grading their own trails. I certainly would not grade that “hiking”.

If you had asked me in advance, I would have told you: The photo does not show hands for advance but hands for balance. So demanding_mountain_hiking perhaps in order. But the only hazard is wet feet, so simply mountain_hiking in order too. Remember, several facets come to play when grading to sac_scale.

Allow for a question: Did you split the way for these 5 metres of ford=stepping_stones to apply sac_scale on it?

Hungerburg · 2024-12-03T22:49:36.793Z

Road_Runner:

And also the relationship to the official sac_scale is already well described in the wiki.

Yes, the relationship is that sac_scale is an off-spring of the Mountain Hiking Scale developped by the SAC (to grade the ways leading to their huts.)

The OSM version in the beginning was written in unintelligible Denglish and since then polished by nice English natives with knowledge of what mountain hiking is about. The SAC version meanwhile also was translated to Denglish. They refer to demanding_alpine_hiking as difficult alpine hiking.

Even though you made some changes to the openstreetmap documentation of Key sac_scale that push it closer to recent editions of the SAC scale, I do not see much value in keeping that cruft. There is no 1:1 mapping any more.

PS: I am still wondering what the strolling value will bring: Will it make hiking harder?

Road_Runner · 2024-12-04T00:30:29.607Z

It makes sense to continue to orientate to the original scale and ratings outside of OSM, even if some people on hikr.org don’t understand the scale, it is sometimes a very valuable resource.

Though the scale has been tweaked slightly, I don’t think any further emancipation makes sense. It’s a mature and established method of rating hiking paths, I don’t think we need to reinvent the wheel.

osmuser63783 · 2024-12-04T08:52:52.815Z

As a compromise between removing it and leaving it as it is:

I imagine it would be helpful for people not familiar with the real SAC scale to have a table that shows the rough equivalents of sac_scale= values in other rating systems e.g. Yosemite Decimal System. That table could also include the Swiss Alpine Club scale with values T1-T6?

In defence of T1-T6, it has some advantages as a shorthand. I imagine this is why it is used in the Tracestrack Topo layer. Calling a path T2 on a scale from T1 to T6 also means you don’t have to explain that something can be =mountain_hiking even if it’s nowhere near a mountain.

rhhs · 2024-12-04T14:28:43.763Z

Road_Runner:

It is the combination of exposure and technical demands that make a trail “difficult”.

But what about trails that are technically demanding but without exposure?

Hungerburg:

The photo does not show hands for advance but hands for balance.

I differentiate between the two by assuming “hands for balance” means just touching something for balance, and “hands for advance” means you have to firmly hold something to advance. Here you have to firmly hold the safety rope to proceed without falling (the next stepping stone my wife is going to step on is wobbly, and the one after that is under water).

The original SAC scale as used by SAC combines technical difficulty, trail visibility, exposure and steepness. However, though often correlated, there are quite a few trails where not all combine to make a difficult trail. We already separated out trail_visibility, while we can also easily separate out steepness (we already have the incline tag for it, and it can be seen on maps with contour lines) so only technical difficulty and exposure remain in sac_scale.
We need to discuss how to tag trails that are technically demanding without much exposure, and easy trails that do have dangerous exposure. I would tag the first group with the sac_scale value that expresses that difficulty, and would tag the second one as an easy sac_scale value + a description of the danger (in the form of a hazard tag if there is one that is appropriate). I.e. sac_scale should primarily describe technical difficulty.