The Los-Angeles Automated Traffic Surveillance and Control (ATSAC) System

The Los Angeles Automated Traffic Surveillance and Control (ATSAC) System is described, emphasizing those features that provide a powerful and flexible capability to manage traffic. Many traffic detectors are used to collect data used for critical intersection control, traffic responsive control in networks, real-time surveillance of traffic conditions using color-graphic monitors, real-time evaluation of system performance, and automated generation of traffic signal timing plans. Closed-circuit television is used to provide additional information regarding the cause of congestion. Manual control of intersections from the control center is used to correct nonrecurring congestion. The hierarchical system architecture consists of a very fast supervisor computer networked with the control console, color-graphic monitors, and area computers that communicate with up to 400 intersections and 1600 detectors each. An evaluation of system performance concluded that stops were reduced by 35%, intersection delay by 20%, travel time by 13%, fuel consumption by 12.5%, and air emissions by 10%. The benefit/cost was 9.8:1, and the system paid for itself in less than one year.<>