(Amended by Ordinance Nos. 182760 and 184957, effective November 25, 2011.) The Director of the Bureau of Transportation shall determine the distance between the improved sidewalk and the property line, which, in residential areas shall generally be 2 feet unless a different distance is specified. The width of the improved sidewalks, the grade thereof, materials for construction or reconstruction, and the location and size of curbs, shall be designated by the City Engineer. The class and kind of any fill materials and requirement thereof shall be designated by the City Engineer. Based on a finding of necessity, the Director of the Bureau of Transportation may permit installation of a temporary sidewalk for a specified period, and the City Engineer shall designate specifications for the temporary improvement.