It used to be that traffic signals were just controlled by pressure switches and timers, and the only way to change the timing of green, yellow and red lights was a technician with a screwdriver. The modern traffic signal system, however, is a true wonder of technology. Sensors throughout the city measure traffic speed and congestion and feed that information to the Traffic Management Center (TMC), which adjusts the timing on intersections to maximize the flow of traffic through the city. The TMC operators (aided by computer alerts) monitor the traffic on large screens and make adjustments on the fly to assist traffic flow.
The TMC has different programs for time of day, days of the week and special events, each of which was created by analyzing traffic flow and creating algorithms (a set of functions and computations) to control the system based on flow. Each of these algorithms is constantly being updated and refined as Denver grows and the traffic flow in and around Denver changes.