The county board shall keep in the office of the county clerk of the county a sufficient supply of the prints of the plans and the printed copies of the specifications and estimates of the cost of construction mentioned in section 39-821, to be furnished by the Director-State Engineer for distribution to prospective bidders and taxpayers of the county. No contract shall be entered into under the provisions of sections 39-810 to 39-826 for the construction or erection of any bridge or bridges unless, for the period of thirty days immediately preceding the time of entering into such contract, there shall have been available for distribution by the county clerk such plans and specifications. The county boards of the several counties shall prepare and transmit to the Department of Transportation a statement accompanied by the plans and specifications, showing the cost of all bridges built in their counties under the provisions of such sections, and state therein whether they were built under a contract or by the county.