Traffic Signal Vocabulary

Green Interval Yellow Interval Yellow Interval

Two or more phases make up a cycle. An interval is the part of a signal cycle during which signal indications do not change. Signal timing is the amount of time assigned to each signal interval. A signal phase is a portion of a signal cycle and consists of the right-of-way (green interval), yellow change, and red clearance intervals in a cycle that are assigned to an independent traffic movement or combination of movements.

The cycle length is the time required for a traffic signal to complete one sequence of all signal indications - - from beginning of green of one phase to the beginning of green of that same phase. The video above shows a signized intersection completing an entire cycle with multiple phases.

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