Study On Transportation Network Design Problem Based On Structure And Link Capacity

ABSTRACT:Transportation network design plays an important role on improving the network functions, optimizing resources, improving travel conditions for the user and so on. The research in recent decades has been made significantly progress. Based on analysis and review of the literatures, this thesis studies the topology optimization problem based on the reliability and stability, hazmat-based urban road transportation network design, and the continuous network design problem considering travel time reliability respectively. Optimization models for these problems are established by mathematical modeling and demonstrated with numerical experiments. The main works of this thesis are as following:Firstly, regarding of reliability and topology stability, the thesis draws the concepts of connectivity reliability and structure entropy respectively to express transportation system, improves them as optimal objectives of system, builds the multi-objective model of connectivity reliability and structure entropy-based discrete transportation network design, and adopts the cross-entropy algorithm to solve the programming problem. The results indicate it is feasible to make both connectivity reliability and structure entropy as optimal objective of system.Secondly, in order to balance risk brought about by hazmat transportation, social justice have been incorporated into the idea of planners. Taking link risk and social equity into account, this thesis establishes a hazmat transport-based network design bi-level model, in which transportation management section at the upper level allocates the link capacities to balance risk, while at the lower level is mixed user equilibrium model and design Particle Swarm Optimization(PSO) to solve the bi-level programming problem. Analysis mainly concentrates on the influence on network risk by network topology, the proportion of hazmat and so on.Finally, the method to accurately simulate users travel behavior in the network design problem is one of the most crucial problems. Considering the link capacities change randomly, travelers are searching for a route such that the travel time reliability is ensured most of the time and the expected unreliability impact is minimized. This tradeoff between the reliable and unreliable aspects of travel time variability in travelers' route choice decision process can be represented by the mean-excess travel time (METT). So the network design problem must take this behavior into account. This thesis designs a continuous transportation network design bi-level programming model based on mean-excess traffic equilibrium model (METE), and uses the PSO solution. Results show the effectiveness of the algorithm for the model, and METT can better reflect the users'route choice behavior.