Freeway traffic surveillance and control

In the past decade, automatic freeway surveillance and control systems have been introduced in several cities in the United States. Effective use of the hardware that has been implemented requires a sound mathematical basis for evaluation and optimization studies. In this paper, the nature of freeway congestion and the structure of systems which have been implemented to relieve this congestion are discussed. Mathematical models of freeway traffic which allow consideration of on-ramp metering control are developed. Finally, several freeway traffic-control problems are discussed, current approaches are described, and formulations of improved (optimal) approaches are developed.