Sidewalks may be of Portland cement concrete or bituminous plant mix at least four inches in thickness except at driveways where they shall be a minimum of six inches. Sidewalks shall be a minimum of four feet in width, and shall be at a uniform distance of 24 inches from the inner line of curb, and should be constructed one inch higher than the top of curb and shall rise one- fourth inch per foot for full width of walk. Sidewalk widths fronting uses other than residential shall be as specified by the Commission. (Ord. 9-3-68.)