The board of county commissioners of any such county is hereby authorized and empowered to issue no-fund warrants during the period of not to exceed three years for the purpose of providing revenue to be used for the construction, reconstruction and repair of bridges and the approaches thereto at a cost to be determined by the county engineer’s estimate not to exceed fifty thousand dollars per bridge, to replace bridges in the county road system which have been destroyed, damaged, or rendered impassable by flood, high water, fire or other casualty. No more than fifty thousand dollars of said no-fund warrants shall be issued in any one year; and not more than one hundred thousand dollars of such warrants shall be issued by said board of county commissioners during the three-year period.