EXPERT-SYSTEM FOR ACTUATED CONTROL OF TRAFFIC AT ISOLATED INTERSECTIONS (EXACT) .2. THE KNOWLEDGE-BASE DEVELOPMENT

This paper describes the development of the knowledge base of the expe rt system EXACT (EXpert system of ACtuated control for Traffic at isol ated intersections). EXACT was developed to assist traffic engineers i n selecting the appropriate type of traffic-actuated controller and it s associated features, the type of detector and its configuration, and time settings at a particular intersection. The knowledge-base of EXA CT consists of three primary elements: frames, parameters, and rules. These elements are activated by a back-word chaining mechanism during a consultation. The ability to explain its reasoning process to the us er is one important feature of EXACT. Moreover, EXACT's knowledge-base has the capability of interfacing with graphics program in order to e nhance the understandability of the system. A full description of the knowledge-base development of EXACT as well as its graphics interface are presented below.