According to the Denzel Alpine Road Scale, all the pass and mountain roads listed, including old, gravel and poorly preserved military roads, are classified in the Great Alpine Road Guide from Denzel-Verlag into levels of driving difficulty. Various factors such as route, surface, width, edge protection, inclines and slopes, absolute and relative height, etc. were used for the overall assessment. The basically vehicle-independent scale comprises five basic grades SG 1 to SG 5 and four intermediate grades (for example SG 3-4).
This scale is also often used outside the Alps to summarize the technical requirements of a route as a guide for travel planning.
Mountain route that is very easy to drive, even for beginners. Slight incline of up to 9%, hardly any or few hairpin bends, normal wide road with good pavement.
Route without significant demands, also to be traveled by predominantly unaccustomed to the mountain. Well-developed hairpin bends, incline up to 15%, no obstruction from oncoming traffic, edge protection. Solid surface, but sometimes uneven.
The route requires practice and safe driving technique on mountain roads. Carriageway almost two lanes, not always free of dust, many curves, often without edge protection, incline also in curves sometimes over 15%
These routes are challenging for even those that are used to the mountains, above-average driving skills are required. Mostly single-lane, little alternative, heavily washed out and sometimes slippery, even in hairpin bends, narrow passages, no edge protection, steep and continuous gradients
Difficult and dangerous route, use at your own risk! Continuously single lane, no evasive options, severe lane narrowing, mudslides, slopes, bends require traversing, narrow passages, no edge protection, very steep and continuous gradients in multi-lane vehicles