Computers: Microcomputers promise less stop, more go: Designers off urban traffic-control systems propose hierarchical schemes to enhance local control, reliability, and maintainability

Spurred by the dramatic increase in the number of vehicles using — and clogging — the streets of today's cities, urban traffic control has undergone various technological changes in recent years in the drive toward greater functionality and efficiency, and more cost-effective equipment. Thus, traffic-control equipment has evolved from electromechanical intersection controllers, through electronic units, to systems employing minicomputers. The recent stage in this evolutionary process is the introduction of microcomputer-based systems.