The highway administrator shall directly supervise the construction, maintenance, repair and reconstruction of all public highways, roads, bridges and culverts in the county. The expenditure of all county road and bridge funds, special or otherwise, shall be approved by the county commission. The county commission shall not order a road established, changed or vacated until its proposed establishment, change or vacation has been examined and approved by the highway administrator in a written report filed with the county commission; except that if the highway administrator does not file a written report on such proposal within thirty days after being notified thereof by the county commission, the commission may proceed to make any orders respecting such proposal without such report.