S.D. Codified Laws § 31-12-9

Before any permanent improvement is undertaken upon the county highway system, the county highway superintendent shall, under the general direction of the board of county commissioners where deemed necessary, make or have made a survey and prepare or have prepared plans, specifications, and estimates for the improvement. Unless the county has adopted its own standards, the survey, plans, specifications, and estimates shall be prepared according to standards to be prescribed by the Transportation Commission, and shall be on the basis and with the object in view of permanent improvement, each as to bridge, culvert, tile, and road work.