Winter driving in cold regions is hard. Knowing where the middle of the road is and the car's position relative to it is only the very start of the problem. In

Winter driving in cold regions is hard. Knowing where the middle of the road is and the car's position relative to it is only the very start of the problem. In regions that have roads not cleared of snow for multiple days the lane positions change. The evolution of the position of the lanes is not strongly defined by where the previous lines were. The obvious spot to drive for a human would contradict the magnetic, ground penetrating radar database, or whatever marker is used. Markers of any type would be useful for awareness of car self position but not sufficient for what the lane has become. Even as a human you have to guess sometimes because it's not possible to sense it. You just have to know what humans would do. Machines aren't great at heuteristics and guessing what humans might do.