A.   Authority Of Mayor: The mayor, subject to any directions which the city council may give by motion or resolution, is empowered to adopt regulations necessary to make effective the provisions of the traffic ordinances of this city and to make temporary or experimental regulations to cover emergencies or special conditions. No such temporary or experimental regulation shall remain in effect for more than ninety (90) days.
   B.   Traffic Control Devices: The mayor may have traffic control devices tested under actual conditions of traffic. (1988 Code § 15-205)