How traffic signal synchronization works

The way traffic signal synchronization works is by calculating the arrival time for a group of vehicles at each intersection traveling at a specified speed, and then  the traffic signals are strategically timed to turn green just as the group of vehicles arrive at each intersection. In order for the traffic signals to be synchronized, a group of signals must all be set to run on the same cycle length (the amount of time it takes for the signal to go from green to yellow to red; and back to green again - after the cross street has been serviced.