As used in Chapter 39, articles 14 to 20, except sections 39-1520.01 and 39-1908, unless the context otherwise requires:
(1) County board shall mean the board of county commissioners in commissioner-type counties and the board of county supervisors in township counties;
(2) Public roads shall mean all roads within this state which have been laid out in pursuance of any law of this state, and which have not been vacated in pursuance of law, and all roads located and opened by the county board of any county and traveled for more than ten years; and
(3) County road unit system shall mean the administration of county and township roads as provided in sections 39-1513 to 39-1518.