Grades shall not exceed ten percent on major residential streets, or fifteen percent on any street, unless the topography shall necessitate steeper grades. Centerline radii shall not be less than five hundred feet. Lesser radii may be approved by the Planning Commission on recommendation of the City Engineer in cases in which sufficient evidence is presented to show that the above requirements are not practicable. (Ord. 89-2 § 2, 1989; Ord. 66 NS § 2.1(d), 1950; prior code § 20-9.)