Hierarchical modeling and simulation environment for intelligent transportation systems

This article presents a hierarchical and modular traffic simulation environment for intelligent transportation systems (ITS). A conventional traffic simulation model is classified as microscopic or macroscopic; however, abstraction-level, vehicle-level, cell-level, road-level, and street-level traffic models can be coherently integrated and developed. Such an abstraction process is important for flexible traffic analysis since it reduces the complexity of a model, retaining its validity relative to the modeling objectives and experimental condition. To do this, the authors have proposed the four-layered approach: (1) system entity structure/model base, (2) model abstraction, (3) traffic modeling, and (4) ITS simulation systems layer. A proposed methodology has been successfully applied for building the advanced traveler information system and the advanced traffic management system. The abstraction method of a road network in traffic modeling and simulation will be widely used because it is possible to express and analyze various requirements of the traffic analyst hierarchically and structurally.