Amusement devices shall be operated only by competent operators at least 16 years of age for devices designed primarily for the use of small children and/or an accompanying adult and 18 years of age for all other devices. Every operator shall have knowledge of the use and function of all normal and emergency operating controls and of the proper use of the device. An operator shall be in the immediate vicinity of the operating controls during operation and no other person shall be suffered or permitted to handle such controls during normal operation. No operator shall be responsible for the operation of more than one amusement device at a time. This provision does not apply to amusement devices designed to be operated or controlled safely by a passenger.