No person shall open the door of a motor vehicle on the side available to moving traffic unless and until it is reasonably safe to do so, nor shall any person leave a door open on the side of a motor vehicle available to moving traffic for a period of time longer than necessary to load or unload passengers. (Ord. 5212 § 1 (Exh. E), 1999; 1957 code § 9.04.362.)