Coming here late, but perhaps some thoughts that can be used moving forward.
Scramble can be used to describe anything from Class 2-4 in YDS so that’s a wide net. Having a highway=scramble lets me know that it’s not Class 1 or SAC 1-2, but I’m more concerned about whether there is fatal exposure and/or semi-technical sections than I am whether I have to use my hands every once in a while for balance. There is too large difference in technique from the low to high end IMO
A strict interpretation scramble as just “use of hands” opens up a lot of normal trails that overlap into YDS Class 2 terrain - the trail in Granite Park outside Pine Creek in the eastern Sierra has a few Class 2 sections and a mantle or two, most of the trails in The Needles in Canyonlands have mantles or drops in them that would push them into this label. I wouldn’t consider them scrambles in the fun semi-technical sense.
demanding_path is a bit odd to me (as many people consider a long or steep hike on a very nice trail demanding)
I could see this being broken down into a few stages that mimick major changes in ratings, though at this point the only real value would be not having this be a subvalue that people may ignore, but something that has to be entered. I’m not familiar with other regional systems, but they should be tested to see how they map onto this (countries that only have 3 are an interesting case, etc).
highway=path Class 1 YDS, SAC 1-2
highway=demanding-path Class 2 YDS, SAC 3
highway=scramble Class 3 YDS, SAC 4-5
highway=mountaineering Class 4 YDS, SAC 6
Breaking down trails in Needles that have some mantles, steps carved into sandstone, via ferrata, etc from those that are just simple single track into categories seems useful for your everyday tourist even if they aren’t “scrambling”.
As an aside:
How you move over terrain in reality is independent of exposure - one can walk on fatally exposed Class 1/2 (a foot wide but mostly flat ridge), or do a short Class 4 SAC 5/6 section which is short and unexposed but requires more technical or athletic skill than the average hiker has. In YDS I will personally shorthand things like “2 X” and “4 PG”, breaking apart technique and exposure into their own axii, but creating new technique and exposure keys is probably too much for this use case.
The following photo shows terrain where we didn’t have to use our hands, but is exposed. It’s still steep enough (and with enough variation that we had to “read” when to stay high or go low etc) that I wouldn’t put it as Class 1, but even at Class 2 it’ll unnerve some people that are comfortable in general on that terrain type. Is it SAC 2 due to the terrain, or SAC 4 due to being exposed?
