If the subdivider elects to construct streets totally out of portland cement concrete or if such pavement is required by the City Engineer, thicknesses of six (6) inches for local and collector streets and seven (7) inches for arterial, commercial, and industrial streets shall be required, and shall meet the current Plain Portland Cement Concrete pavement specifications of the Ohio Department of Transportation. The Planning Commission may require pavements of greater thickness, upon the recommendation of the City Engineer, based upon his or her evaluation of the subgrade, traffic, and wheel load conditions.