Signals + Meters

The basic timing cycle for traffic lights, called the background cycle, is generally determined by the width of the road multiplied by a pedestrian walking time of 3.2 feet per second. If no pedestrians are present, the cycle may be accelerated or reduced. Before the integration of signalized intersections to a central control point, all intersections functioned autonomously, with loop counting circuitry and timers located in a pole box at the base of a traffic signal pole, or in a metal cabinet on the sidewalk. Though most intersections still possess the ability to operate in this manner, they are increasingly becoming connected by phone lines and dedicated copper wire to the computers at traffic management centers. In the City of Los Angeles, 3,000 of the 4,200 signalized intersections in the city are connected to the Automated Traffic Surveillance and Control Center.