The City Traffic Engineer is authorized to establish and maintain and to designate upon the surface of the roadway by appropriate devices, marks or painted lines, crosswalks approximately equal in width to the adjacent sidewalk at all intersections where in his opinion it is a particular danger to a pedestrian crossing the roadway. In addition, he may establish crosswalks fifteen feet in width as near the middle as it is practicable of any block. (Ord. 2730 § 1, 1990: 3210.34 -- Ord. 996 § 2 (part), 1959).