Signal heads require at least how many signal faces?

• A. 2
• B. 4
• C. 1
• D. 3

Answer: (D)

The main idea here is that a signal head is designed to serve a separate approach with its own display. Each signal face is a complete set of signals (red, yellow, green) oriented toward a specific direction of travel. To properly control traffic at a typical intersection, you need a signal face for each approach—left, straight, and right—so you can show the appropriate signal to vehicles coming from any of those directions. That’s why you need at least three signal faces on a signal head. Some intersections use more faces for additional approaches or lanes, but three is the minimum to cover the main directions.