Traffic control devices must retain which important qualities?

Traffic control devices play a critical role in ensuring safety and efficient traffic management, making their qualities essential for effective operation. The characteristics of visibility and function are particularly crucial.

Visibility ensures that all drivers and pedestrians can easily see the traffic control devices from a distance, regardless of weather conditions or time of day. This is vital for compliance and safety, as clear visibility allows road users to react appropriately to the signals and warnings that the devices provide.

Function relates to how effectively these devices perform their intended purpose. A traffic control device must convey the correct information to manage traffic flow, alerting drivers to hazards, indicating directions, and guiding them safely through work zones or other areas. If a device is not functional, it can lead to confusion, accidents, or improper navigation.

While other options highlight important traits such as durability, design, and cost efficiency, the fundamental qualities of visibility and function are indispensable for the immediate and effective operation of traffic control devices. These are the characteristics that ensure traffic safety and proper guidance in any context, especially in work zones where the risk of accidents can increase significantly.