The feature "surface" should have only the values paved and unpaved. This is easyer for a first crude characterization of a way for everyone . After this, the ways may be characterized with more details. Two additional properties should be used. One for the crude quality and one for the material quality. Other pictures with special requirements are desired and everyone is asked to find a good description for this.
surface_macro - plane (eben) - wavy (wellig) - holey (löchrich) - softly (weich)
surface_micro - smooth (Beton, Asphalt) - sandy (sandig) - stony (steinig) - plant (pflanzlich) - ice