Whenever it is deemed necessary because of construction or maintenance work or because of emergency, the county commissioners may, subject to the recommendation of the commissioner in charge of the county road department, restrict the use of, or close, any highway or portion thereof. Whenever such highway or portion thereof is restricted or closed to travel, the road department shall erect or cause to be erected suitable barriers and notices to be posted at the point where the detour road takes off from the closed or restricted highway, and the detour road shall be clearly indicated by signs and adequately maintained. (1988 Code § 9.04.070)