Which element of signal timing describes the group of traffic movements allowed to proceed together during a cycle?

• A. Actuated Signal
• B. Greenshield's Model
• C. Arterial Highway
• D. Phase

Answer: (D)

In signal timing, a phase is the group of traffic movements allowed to proceed together during a cycle. The cycle is divided into phases, each giving a green signal to specific movements that can operate simultaneously without conflicting with other movements. The duration of a phase is set to accommodate the volume of those movements and to fit pedestrian crossing times and clearance intervals. For example, one phase might allow north–south through and protected left-turn movements together, while another phase handles east–west traffic. Other terms describe different concepts: an actuated signal refers to timing that changes based on detectors, Greenshield's Model relates speed to density in traffic flow, and an arterial highway is a road type, not the grouping of movements in a cycle.