There are are usually snow markers* – tall poles marking the road, but nowadays I guess GPS does most of the locating.
*In cold countries, roads often have poles by the side to help guide drivers during heavy snowfall or blizzards. These poles, known as snow poles or snow markers, are usually taller than the average snow depth and help drivers see the road’s edges and curves when snow covers the ground. They also assist road maintenance crews in identifying the road’s location for plowing and maintenance purposes.
These are from Hemsedalsfjellet via Google Street View.
