Design, operation, and utilization of changeable-message signs with emphasis on the retating-drum type.

Although tables are presented on the functions and types of changeable-message signs available, the rotary drum type is singled out for special attention. Basically, it is described as a triangular-shaped drum pivoted on each end, mounted within an enclosure with rotors attached to each face bearing the message sign. Two types of remote control systems are described.