Amends GS 20-114.1 to require that appointed traffic-control officers be at least 21 years old rather than 18 years old. Conditions appointment as a traffic-control officer upon completion of a training course in traffic laws and traffic control (previously not required) and completion of at least four hours of roadside training in directing, controlling, or regulating traffic under the supervision of a law-enforcement officer (was, at least three hours and did not specify roadside training). Specifies that the training course and roadside training are to be conducted by the law enforcement agency issuing the authorization card for appointment. Adds that any costs of the training are the responsibility of the traffic control officer trainee. Effective October 1, 2019.