Difficulty scales and surface
Every trail stores SAC, YDS, and a plain label together. Surface is a separate field. A missing surface is not guessed from the grade.
SAC
- T1. Hiking. Trail well cleared, flat or slightly sloped, no fall hazard.
- T2. Mountain hiking. Continuous trail, some steep ground, sure-footedness helpful.
- T3. Demanding mountain hiking. Exposed sections possible; hands may be needed for balance.
- T4. Alpine hiking. Sometimes pathless; exposure and simple climbing terrain.
- T5. Demanding alpine hiking. Often pathless, exposed, climbing to II; glacier possible.
- T6. Difficult alpine hiking. Mostly pathless, climbing to III, high exposure and glaciers.
YDS
YDS class is the site cross-walk from SAC. It is not a climbing-guidebook grade unless an official grade is also stored.
Surface
Allowed values, mapped from OSM surface tags only:
- Paved
- Compacted
- Gravel
- Dirt / earth
- Rock