It shall be the duty of the county engineer to:
(1) Employ, supervise, and direct all assistants to properly maintain and construct the public roads, highways, bridges, and ferries of the county, and prescribe the duties of these employees and discharge employees for cause or when employees are not needed.
(2) Perform engineering and surveying service as may be required, and to prepare and maintain the necessary maps and records.
(3) Maintain the necessary accounting records to reflect the cost of the county highway system.
(4) Build or construct new roads, or change old roads, but only when ordered to do so by proper order of the county commission.
(5) Construct and maintain all county roads on the basis of the county as a unit to the extent it is feasible, without regard to any district or beat lines.
(Act 98-75, p. 90, §3.)