The Department is hereby authorized to determine those structures or freeways or portions thereof, upon which travel by pedestrians constitutes a hazard. When such determination has been made, in any case, the Department is directed to post signs giving notice that such places are closed to pedestrian travel. When such signs are in place, it shall be unlawful for any pedestrian to go or travel upon, along, or across such structure, freeway, street or public way, except to perform public work or official duty or when unavoidable as a result of an emergency. (Amended by Ord. No. 134,523, Eff. 7/17/67.)