A speed limit sign is categorized as which type of device?

• A. Traffic control device
• B. Warning sign
• C. Guide sign
• D. Regulatory sign

Answer: (A)

Understanding how signs are categorized by function helps you know why a speed limit sign fits where it does. A speed limit sign communicates a legal requirement that drivers must not exceed a specified speed. That purpose—regulating driver behavior—places it in the regulatory family of signs, which are designed to impose rules and enforce obedience. In traffic engineering, regulatory signs are a type of traffic control device, the broad category that includes signs, signals, and markings used to regulate, warn, or guide road users. Because the speed limit sign’s primary role is to control the rate of travel, it’s best described as a traffic control device. It’s not a warning sign, which alerts you to hazards, nor a guide sign, which provides directions or services.