Tri-level programming model for combined urban traffic signal control and traffic flow guidance

In order to balance the temporal-spatial distribution of urban traffic flow, a model is established for combined urban traffic signal control and traffic flow guidance. With consideration of the wide use of fixed signal control at intersections, traffic assignment under traffic flow guidance, and dynamic characteristics of urban traffic management, a tri-level programming model is presented. To reflect the impact of intersection delay on traffic assignment, the lower level model is set as a modified user equilibrium model. The middle level model, which contains several definitional constraints for different phase modes, is built for the traffic signal control optimization. To solve the problem of tide lane management, the upper level model is built up based on nonlinear 0-1 integer programming. A heuristic iterative optimization algorithm(HIOA) is set up to solve the tri-level programming model. The lower level model is solved by method of successive averages(MSA), the middle level model is solved by non-dominated sorting genetic algorithm II(NSGA II), and the upper level model is solved by genetic algorithm(GA). A case study is raised to show the efficiency and applicability of the proposed modelling and computing method.

Dynamic route guidance algorithm based onartificial immune system

To improve the performance of the K-shortest paths search in intelligent traffic guidance systems, this paper proposes an optimal search algorithm based on the intelligent optimization search theory and the metaphor mechanism of vertebrate immune systems. This algorithm, applied to the urban traffic network model established by the node-expanding method, can expediently realize K-shortest paths search in the urban traffic guidance systems. Because of the immune memory and global parallel search ability from artificial immune systems, K shortest paths can be found without any repeat, which indicates evidently the superiority of the algorithm to the conventional ones. Not only does it perform a better parallelism, the algorithm also prevents premature phenomenon that often occurs in genetic algorithms. Thus, it is especially suitable for real-time requirement of the traffic guidance system and other engineering optimal applications. A case study verifies the efficiency and the practicability of the algorithm aforementioned.

Research on an Urban Traffic Control System Based on DGPS

The basic principles of GPS (Global Positioning System) and DGPS (Differential GPS) are described. The principle and structure of vehicle navigation systems, and its application to the urban traffic flow guidance are analyzed. Then, an area coordinated adaptive control system based on DGPS and a traffic flow guidance information system based on DGPS are put forward, and their working principles and functions are researched. This is to provides a new way for the development of urban road traffic control systems.

Theory and Architecture of Urban Traffic Flow Guidance System

This paper is based on major project supported by National Natural Science Foundation of China (NSFC). The Theory and Architecture of Urban Traffic Flow Guidance System (UTFGS) will be offered by this paper. The research of UTFGS has a significant value of theory and reality. It is not only key part of Intelligent Transportation System (ITS) but also important research field of ITS in China.

Method of Generating Strategic Guidance Information for Driving Evacuation Flows to Approach Safety-Based System Optimal Dynamic Flows: Case Study of a Large Stadium

In previous evacuation flow planning, a system optimal dynamic traffic assignment(SODTA) did not consider the exogenous costs caused by potential traffic accidents. A traffic accident,which might occur as a result of traffic congestion, will impact an evacuation process because of accidentrelated delays experienced by the downstream vehicles. This paper establishes a safety-based SO-DTA linear programming model in which the generalized system cost incorporates both the travel time and the accident-related delay. The goal is to minimize the generalized system cost under the cell transmission setup. Furthermore, the authors provide strategic guidance information that considers both the objective of the decision maker and the route choice behavior of the evacuees. Mathematically,the authors propose an unconstrained non-linear programming model aimed at minimizing the gap between the safety-based flows and the stochastic real-world evacuation flows, to provide strategic travel time information to be published on variable message signs(VMS). In the case study, the authors found that the safety-based SO-DTA model can reduce congestion and improve the evacuation efficiency; the stochastic real-world evacuation flows, guided by strategic information, can approach the safety-based flows.