Study On The Dynamic Impedance Functions And Routing Optimizes Methods Of The City Traffic Flow Guidance System

Intelligent Transportation System(ITS)is based on the modern advanced science and technology, and it is the application of computer technology, communication technology, database technology and artificial intelligence to transportation. It aims to settle traffic congestion, guarantee traffic safety, and raise efficiency of utilization of traffic network. ITS covers a wide range of transportation systems, in which Routing Guidance System is an important application and one of hotspots of domestic ITS development and application at present.This paper is based on the above-mentioned situations and aims at the routing optimization method's research, which is the hard core of the routing guidance system. It is composed of two parts: The research on the dynamic link impedance functions and routing optimizes techniques of Routing Guidance System.First part: The Routing Selection is based on the dynamic link impedance functions, which is the overall system's work foundation. After analysis and comparison is made to some dynamic link impedance functions used in abroad as well as in our country, we point out their advantages and disadvantages, and bring forward a new model which is based on the principle of distributing wave in the traffic flow. This model is used to calculate the cost of the road. At the end, according to the realistic situation of city traffic some amends are made to the function.Second part: The routing optimizes techniques is the key of the routing optimization system, and its choice is related to the whole system's timeliness and validity. After the comparison of the traditional algorithms in the routing optimizes techniques, we choose the Genetic Algorithm. And this genetic algorithm is changed in the encoding and crossover manners. It uses Priority-based Encoding and Weight Mapping Crossover to improve the common genetic algorithm, namely WMC GA.In the end of the paper, a dynamic routing guidance plan is put forward according to the real-time traffic flow guidance system. And the WMC GA is used to solve the optimizes problem in this plan, which has proved the methods'superiority and feasibility.