ABSTRACT
Traffic operations are activities that maintain or increase a road’s carrying capacity for both vehicles and people by means other than adding additional through lanes. A traffic signal, or traffic light, is a device used to direct vehicle and pedestrian movements at an intersection, ensuring both flow efficiency and safety. After a roadway opens to traffic, traffic signal operations are very closely monitored in the near term, adjusted, and retimed as the flow pattern reaches a stable condition. From there, signals are retimed periodically as flow patterns may change significantly. A pre-timed traffic signal controller cycles through a pre-established green-yellow-red sequence with predetermined time durations for the green, yellow, and red indicator lights, regardless of up and downstream traffic conditions or any other traffic controllers. A pre-timed coordinated traffic signal controller cycles through a pre-established green-yellow-red sequence with predetermined time duration for each of the green, yellow, and red indicator light regardless of actual field traffic conditions.
