Mo. Rev. Stat. § 243.320: Public roads and railroads to pay benefits.

When any ditch constructed under the provisions of this chapter drains, either in whole or in part, or benefits any public or corporate road or railroad, there shall be apportioned to the county, if a county or state or free turnpike road, or if a corporate road or railroad, to the company owning, operating or controlling the same, the same proportion of the cost of location and construction of the improvement in proportion to the benefits received as to private individuals.