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

[erutan]

@rhhs

Maybe the Value 5 description needs a bit clearer wording: reading “Feet are off the ground” and “You need to be able to pull up your body weight with upper body strength” makes me imagine one is required to pull oneself up by the arms only, like when using a pull up bar. I think what is meant is that the strength of both arms and legs (but mainly legs) is needed for this scale?

Yeah I’ll take a look at that. It was meant to distinguish from just needing to mantle over a ~waist high obstacle etc. Moving from handhold to handhold is probably another useful way to phrase it.

@rhhs

I suppose it has also been discussed how to implement this new key. Can you summarise it? Will this key replace the old sac_scale key? By automated replacement of sac_scale=hiking with foot_scale=casual_or_attentive_FIXME, etc.? Maybe Switzerland needs a special treatment: there will be many cases where paths there are tagged with sac_scale=* because that’s what they have been judged to be by the SAC itself. So paths in Switzerland could have both a foot_scale=* tag added by an OSM mapper and a (verifiable!) sac_scale=* tag, now redefined as “hiking difficulty according to the SAC”.

Take a look at this comment here by @osmuser63783 and my response: RfC: New Key foot_scale=* ("now for something a bit recreational") - #115 by osmuser63783

It’s not a 1:1 clean mapping, but in general SAC T1 should be casual or attentive, T2 surefooted, T3 hands for assistance (some overlap into light T4), T4-T5 scrambling, T6 no longer a foot path (potentially). There’d need to be a verify tag, but I feel this would be a good starting point and foot_scale is more intuitive globally. No more easy single track trails in commonwealth countries tagged as being alpine_hiking because they’re above treeline. sac_scale gets misused a lot on OSM, so I imagine even with mapping mismatches you’d have a lot of bad data just from the input side.

foot_scale can exist alongside other local scales - renderers can choose to implement what they want. Especially in scrambling this becomes important, I can see YDS, BMC, SAC, etc being used to differentiate sub grades of a scramble which aren’t appropriate for 99.9% of recreational users and would be best kept to local norms anyways. Having some sort of tag that an agency has rated something seems like a very useful idea.

I’m more of a hiker than a hardcore OSM editor, so other people are better suited to discuss the details of porting data over. There’s a decent argument to be made that (globally) sac_scale is an inconsistent mess and it might not be worth porting as there’d be a lot of misinformation.