If it is objected on the part of any property assessed for such an improvement, that it will not be benefited thereby to the amount assessed thereon, and that it is assessed more than its proportionate share of the cost of the improvement, and a jury is not waived by agreement of parties, the court shall impanel a jury to try that issue. In that case, unless otherwise ordered by the court, all such objections shall be tried and disposed of before a single jury. The assessment roll, as returned by the officer who made it, or as revised and corrected by the court on the hearing of the legal objections, shall be prima facie evidence of the correctness of the amount assessed against each objecting owner but shall not be counted as the testimony of any witness or witnesses in the cause. That assessment roll may be submitted to the jury and may be taken into the jury room by the jury when it retires to deliberate on its verdict. Either party may introduce such other evidence as may bear upon that issue or issues. The hearing shall be conducted as in other civil cases. If it appears that the property of any objector is assessed more than it will be benefited by the specified improvement, or more than its proportionate share of the cost of the improvement, the jury shall so find, and it shall also find the amount for which that property ought to be assessed, and judgment shall be rendered accordingly.