As the cycle length is increased, the amount of time given to the red lights increases, meaning longer delays and longer lines of cars. This balancing act becomes more difficult at intersections with left turn arrows, because this is a separate phase. These signals, which commonly are found in Town, have eight or more phases, increasing the cycle length. The quality of progression can be very sensitive to these cycle lengths. When signals are irregularly spaced, providing progression can be a very difficult task. On some streets, full two-way progression is only possible for very short stretches. Good coordination plans must be updated whenever traffic volumes increase or new signals are added. Despite the difficulties, good signal coordination benefits include reduced auto air pollutant emissions, reduced delay for drivers, improved roadway efficiency and decreased fuel consumption.
Reviewed Mar. 15, 2023