65 ILCS 5/9-2-101

Except as otherwise provided in Section 9-2-113, if the ordinance provides for alternate specifications for the kind, nature, character, and description of a proposed improvement, or the materials to be used in its construction, and more than one estimate has been prepared, then the assessing officer or commissioners appointed to make the assessment shall make his or their report and assessment roll, based upon the highest estimate of the cost of the proposed improvement.