Mo. Rev. Stat. § 88.824: Costs of improvement to be estimated — contracts not to exceed estimate.

Before the governing body of the municipality shall make any contract for building bridges, sidewalks, culverts or sewers, or for paving, macadamizing, curbing, guttering or grading any street, avenue, alley or other highway, or building any other improvements authorized herein, an estimate of the cost thereof shall be made by the engineer or other proper officer or person designated by ordinance and submitted to the governing body of the municipality, and no contract shall be entered into for any work or improvement for a price exceeding the estimate; provided, that no estimate shall be required for the making of any local or special repairs.