Grades shall not exceed fifteen percent on major residential streets, or twenty-five percent on any street, unless it is determined by the City Engineer that the topography shall necessitate steeper grades, and twenty-five percent maximum on any driveway. Centerline radii on any street shall not be less than one hundred feet where normal topographical conditions prevail. Lesser radii may be used in cases in which sufficient evidence is presented to show that the above requirements are not practicable. (Ord. 5793-NS § 2 (part), 1987)