FRAMEWORK FOR THE INTEGRATION OF DYNAMIC TRAFFIC ASSIGNMENT WITH REAL-TIME CONTROL

Advanced Traffic Management Systems (ATMS) and Advanced Traffic Information Systems (ATIS) are being designed to provide real-time control and route guidance to motorists to optimize traffic network performance. An essential requirement is to have a dynamic traffic assignment (DTA) capability which predicts motorist behavior and enables the development of suitable control strategies in real time. In this paper the authors present a framework for the integration of DTA with real-time control. They discuss first the static case, involving the interaction between travelers (demand) and transportation facilities (supply) under recurrent conditions, and provide a mathematical model for their interaction. This model is applicable in the design and planning of transportation systems management (TSM) actions. Then they extend the framework to the dynamic case, which involves the incorporation of advanced intelligent transportation systems (ITS) technologies in the form of ATMS and ATIS. This framework is particularly applicable to the integration of DTA with advanced traffic adaptive signal control. Current technology consists of disparate computational procedures for flow prediction (traffic assignment) and for traffic control (signal system optimization). This may lead to an inconsistency between the predicted volumes and the calculated controls and, therefore, to non-optimal operating conditions. To obtain optimal performance it is necessary to combine the two components into an integrated system which can produce on-line optimal control strategies and dynamic route guidance information.