A sunken lane is a road or track that is significantly lower than the land on either side, not formed by the engineering of a road cutting but possibly of much greater age.
Various mechanisms have been proposed for how holloways may have been formed, including erosion by water or traffic; the digging of embankments to assist with the herding of livestock; and the digging of double banks to mark the boundaries of estates. These mechanisms are all possible and could apply in different cases.
Wikipedia https://en.wikipedia.org/wiki/Sunken_lane
Address (Unnamed Road), 79346, Germany
Coordinates 48°7'56.853" N 7°42'44.895" E