No person shall stop, stand, or park any vehicle upon a street or alley, in such manner or under such conditions as to leave available less than ten feet of the width of the roadway for free movement of vehicular traffic, except that a driver may stop temporarily during actual loading or unloading or when necessary in obedience to traffic regulations or traffic signs or signals or a police officer. 
(‘65 Code, § 74.04)  Penalty, see § 70.99