It shall be the duty of the county engineer or road supervisor to make a written report to the board of county commissioners of the work accomplished and funds expended upon all the roads and bridges for the current year, which shall close on the thirty-first day of December of each year. This report shall show which roads of the county and township systems have been completed or partially completed, and credit to such roads shall be shown upon the county road plan not later than April 15, and a copy of the report shall be immediately forwarded to the state transportation engineer upon standard printed forms.