single n.— «Bike trails are commonly known as “singles,” because they constitute narrow trails just wide enough for a single bicycle bearing one rider. Bikers ride in a single file and blend in with nature and the topography...
viewshed n. the landscape or topography visible from a geographic point, especially that having aesthetic value. Etymological Note: This term is directly related to watershed ‘an area or ridge of land that separates waters flowing to different...