1. In addition to the comprehensive road plan required by section 230.235, all counties of the third class adopting sections 230.200 to 230.260 shall employ a qualified graduate civil engineer as county highway engineer; except that, any person serving as county highway engineer on the date the county for which he serves adopts the provisions of sections 230.200 to 230.260 may be retained as county highway engineer and shall be considered qualified for that position within the meaning of sections 230.200 to 230.260. The county highway commission shall appoint the county highway engineer and shall set his salary to be paid out of the road and bridge fund of the county. The services of the engineer shall be available in an advisory capacity to any incorporated municipality within the county at no charge to the municipality.

2. The county highway engineer shall have general supervision over the construction, maintenance, repair and reconstruction of all public highways, roads, bridges and culverts, subject to the approval of the county highway commission.