Except when authorized or directed under state law to immediately take a person arrested for a violation of any of the traffic laws before a magistrate, any police officer, upon making an arrest for a violation of the state traffic laws or the traffic code, shall take the name, address and operator's license number of the alleged violator and the registered number of the motor vehicle involved and shall issue to him in writing on a form provided by the city, a notice to answer to the charge against him at a place and at a time after the arrest to be specified in the notice. The officer, upon receiving the written promise of the alleged violator to answer as specified in the notice, shall release that person from custody.
('71 Code, § 70.28)