Design of Traffic Light Control Systems Using Statecharts

Abstract

Statechart has been utilized as a visual formalism for the modeling of complex systems. It illuminates the features on describing properties of causality, concurrency and synchronization. This paper focuses on the use of statecharts to model an urban traffic lights control system. The applications of statecharts to eight-phase, six-phase and two-phase traffic lights are illustrated. The advantage of the proposed approach is the clear presentation of traffic lights' behaviors in terms of conditions and events that cause the phase alternations. Moreover, the paper also proposes a new modeling methodology, called concurrent state graphs, that allows us to present all the concurrent states in complex statecharts. The analysis of the control models is performed to demonstrate how the models enforce the lights' transitions by reachability tree method. And then the reachability and reversibility properties of the control statecharts will be obtained. Finally, an urban traffic lights' control system with nine intersections will be realized. To our knowledge, this is the first work that employs statecharts to obtain the models of the urban traffic light control system.