Integrated modeling of information and physical flows in transportation systems

Modeling transportation systems operations in large part involves an understanding of how physical entities (i.e., vehicles) move and interact with each other in the system. Transportation systems that are integrated with information technologies involve flow of information besides the flow of physical entities. In some cases, a unified modeling approach that considers both flows is needed to create an accurate model for system operations. This paper highlights the significance of such a modeling approach that involves an explicit representation of information flow attributes (e.g., response time and information delay). Several small-scale queuing models are developed to illustrate the importance of incorporating information flow related attributes into the models of transportation systems operations. In each example system, two scenarios are considered: modeling the given system with or without explicitly representing the information flow. Comparison of performance statistics is made between these two scenarios. It is found that ignoring information flows may lead to significant inaccuracies in the estimates of the system performance.