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Public-images-osm logo.svg sac_scale
Mountain hiking.jpg
A difficulty rating scheme for hiking trails Edit or translate this description.
Group: Properties
Used on these elements
should not be used on nodesmay be used on waysshould not be used on areasshould not be used on relations
Useful combination
Status: approvedPage for proposal

This is part of a classification scheme for hiking trails, this key describes attributes regarding difficulty.

It is based on the Klassifikation des Swiss Alpine Club (SAC) (de) since there is no internationally standardized classification schema.

All properties that deal with trail visibility and orientation have been extracted to a separate key trail_visibility=*

Consider using this for any paths that are not easily walkable. If in doubt about exact difficulty err on the safe side and add a fixme with explanation. This is because highway=path is used from anything from urban paved footways to difficult mountain paths and in case of missing data about difficulty routers/maps could direct unprepared hikers to difficult terrain.

Applies to

Suggestions, not part of the original voted proposal

  • It is suggested not to use this tag on paths not used for hiking or climbing.
  • Be aware that many renders show all paths (even Via Ferrata/Klettersteige) as dashed line. Consider an appropriate name for the way.
  • Tracks can carry a sac_scale=* tag if they are hiking trails/paths that are wide enough to carry a vehicle, if commonly (dual-)used for hiking or marked with hiking signs (Alpenverein, tourist authority). Generally the sac_scale=* of a track should be hiking or rarely mountain_hiking (if hazardous/slippery, map navigation required, etc.)

General Notes

As this is a more or less direct translation from the Swiss Alpine Clubs hiking difficulty assessment, this is generally suited for mountainous areas. For non-mountainous regions, other difficulties and requirements are present and therefore other scales should be used. E.g A way in a forest that is difficult to walk because of muddy ground and trees or bushes making walking difficult does not classify for T2. Other keys need to be used to describe its condition.

Most hiking trails that are found in maps fall into the T1 and T2 category. In low mountain ranges ways are often T1.

Often mappers in OSM have mapped T1 or T2 trails as T4 therefore some more notes to help understand what the below words mean.

Alpine: Alpine areas are posing the hiker greater difficulties. Exposed sites, boulders and debris, remoteness, high altitude, the possibility of rapid weather changes and often pathless routes that may change depending on conditions and time of the year are all factors that make up alpine regions. Note that just because a way is at high altitude but well maintained (e.g. cablecar nearby that carries tourist up to the Gornergrat ) means that even though a way is in alpine surroundings, the way itself should not be classified T4-T6. In alpine areas dangers such as avalanches, crevasses, falling rocks or ice mean that the difficulty of a way is not the way alone, but also the requirement to know how to handle such situations.

Mountaineering Boot: Mountaineering boots are much heavier and stiffer than the popular and lighter trekking or hiking boots. The have a thicker rubber sole and are torsionally stiffer. They are not only compatible with crampons but are stiff enough to make it comfortable to walk for hours with crampons (Trekking boots on the other hand require strap-on crampons). They enable the hiker to kick steps into hard snow. They often consist of an outer and a liner which can be taken out for drying. 1


The illustration images have been provided by Marco Volken, member of the SAC trail classification working group.

Tag SAC Scale Trail Terrain Requirements Illustration
sac_scale=hiking T1 yellow Trail well cleared Area flat or slightly sloped, no fall hazard None
sac_scale=mountain_hiking T2 red Trail with continuous line and balanced ascent Terrain partially steep, fall hazard possible
  • Hiking shoes recommended
  • Some sure footedness
sac_scale=demanding_mountain_hiking T3 red exposed sites may be secured with ropes or chains, possible need to use hands for balance Partly exposed sites with fall hazard, scree, pathless jagged rocks
  • Well sure-footed
  • Good hiking shoes
  • Basic alpine experience
sac_scale=alpine_hiking T4 blue sometimes need for hand use to get ahead Terrain quite exposed, precarious grassy acclivities, jagged rocks, facile snow-free glaciers
  • Familiarity with exposed terrain
  • Solid trekking boots
  • Some ability for terrain assessment
  • Alpine experience
sac_scale=demanding_alpine_hiking T5 blue single plainly climbing up to second grade Exposed, demanding terrain, jagged rocks, few dangerous glacier and névé
  • Mountaineering boots
  • Reliable assessment of terrain
  • Profound alpine experience
  • Elementary knowledge of handling with ice axe and rope
sac_scale=difficult_alpine_hiking T6 blue climbing up to second grade Often very exposed, precarious jagged rocks, glacier with danger to slip and fall
  • Mature alpine experience
  • Familiarity with the handling of technical alpine equipment


Tag SAC Scale (as seen on ground signs) Alpine Paper Maps (Austria)
sac_scale=hiking T1 yellow solid red
sac_scale=mountain_hiking T2 red dashed red
sac_scale=demanding_mountain_hiking T3 red dashed red
sac_scale=alpine_hiking T4 blue dotted red
sac_scale=demanding_alpine_hiking T5 blue dotted red
sac_scale=difficult_alpine_hiking T6 blue dotted red


Based on the guidelines of Verifiability some people find this tag lacking of verifiablity. Please have a look at the discussion page at Talk:Proposed_features/Hiking and make up your own mind. As always on OSM you are free to use the keys you like in the way you like! You can use the talk page for suggesting improvement.

Many mappers think that the more difficult SAC levels violate common sense expectation of a "highway=path". This key should not serve as an example for the introduction of similar keys, see also troll tag.

Reasons to use it

  • Especially for mountain trails, it is crucial to know whether a trail can be done in sneakers or whether you need an ice axe and climbing irons.
  • Since Google Maps and the like are pretty unusable for hiking (because they denote only very few trails), this is a region where OSM can be of great value soon and for a long time.
  • Many mountaineers already utilize GPSs. It would be great to win as many of them as possible as contributors to OSM.

See Also