Which of the following equipment is commonly used for traffic control in work zones?

The use of portable traffic signals in work zones is fundamental to managing vehicle and pedestrian traffic safely and efficiently. These signals provide directional guidance and help regulate the flow of traffic in areas where road work is taking place, reducing the risk of accidents and congestion. They can be set up to control traffic patterns, especially in locations where traditional traffic signals may not be operational due to construction.

Other options listed do not serve the primary function of traffic control. Public address systems, while useful for communication, do not control traffic flow. Vending machines and water coolers are entirely unrelated to traffic management and do not contribute to what is necessary for ensuring safety in work zones. Hence, the focus on portable traffic signals highlights their critical role in creating a safer environment for both workers and motorists.