I was intrigued by the photo on the wiki illustrating the hardest level of the Swiss Alpine Club scale for mountain hiking (known as SAC Scale on OSM and tagged with sac_scale). I couldn’t identify the location and wondered by looking for ways with the tag I could do better.
A few of the more egregious examples:
- Geant-Rochfort Arete. A classic high-level snow ridge encompassing a couple of 4000ers. Tagged with highway=path and sac_scale:
Description of route on Hikr.
- Biancograt of Piz Bernina: apparently trail visibility is horrible, which is a bit of a surprise, because the ridge is rather narrow.
- Normal route for Piz Palu. At least this is what it looks like to me, although it is labelled “Piz Spinas - Cresta SW” and when I’ve been at Diavolezza the route through the ice falls has been somewhat different. Although this route is immensely popular most of it is over a very steep glacier with two major ice falls. The existence of significant objective dangers was used in the 1929 movie Die weiße Hölle vom Piz Palü starring Leni Riefenstahl.
The normal route from Diavolezza contours above the crevasse field in the foreground and then passes through the lower ice fall quite close to the rock wall on the left before ascending to the minor col to left of the E summit.
There are numerous other normal ascent routes for significant peaks in the Pennine Alps. It is obvious that the tag has been used as follows:
- normal ascent routes which will be heavily used in the alpine climbing season. In good weather the route taken by climbing parties will be clear, but once fresh snow falls earlier traces are often effaced. On rock it is still possible to lose the line of a frequently climbed route.
- as a proxy for accurate Alpine Climbing grades (F/PD/AD/D/TD/ED or L/WS/ZS/S/SS/AS etc)
- often with a highway=path tag (although this was deleted in the case of the Matterhorn)
- sometimes with surface or trail_visibility tags to perhaps indicate these are not actually paths.
As normal hikers are extremely unlikely to undertake a difficult_alpine_hiking tour (T6 grade), the immediate impact on OSM users is probably not anything to worry about. In the past I followed a few T5 routes, and they were slightly above my comfort level, so I would never have undertaken a correctly graded T6 on my own. However the difference between T6 and all these routes is much greater than that between T5 and T6. They require much more equipment and very different techniques: safe glacier travel, crevasse rescue, climbing at UIAA III, etc).
Elsewhere in the world there have been problems with people assuming a path on OSM represents something within their capabilities. We have a responsibility to ensure the data within OSM does not exacerbate such issues.