The fundamental issues of an expert system for urban traffic control

The variety of methods available to the engineer to control traffic movements in a town or city, includes traffic signal control, which can be implemented as isolated junctions, or in coordinated groups, or over the entire network, using either vehicle actuated, fixed-time or demand responsive control. It is the `experts´ who, knowing the capabilities and the limitations of the different systems available, establish the correct balance in the application of the various control strategies to a particular town or city. To cater for congestion in an urban network a fourth generation expert system of control is believed necessary. Such a system will be based on automatic incident detection, continuous monitoring of traffic data online, and definition of remedial strategies offline for the implementation of route guidance. The hardware and computer technology exist to make a start on developing an expert system but the data management framework and algorithms to translate the raw occupancy data into effective control strategies using route guidance are not fully researched. The paper presents the results of research which provides some of the foundations for the building of an expert system, and proposes a way forward in achieving a fourth generation of control