The Influence of Traffic Environmental Variation to City Function Localization Based on the System Dynamics

System dynamics model is established to explore the relations of mutual restriction and mutual promoting between the transportation and the city function localization; Then, by analyzing and comparing the existing methods for the division of urban economic region, the paper sets up the city radiation scope method model. In the model, put forward for the first time to use "the space-time distance" to replace "the transportation distance", and "the city comprehensiveness mass" to replace "the urban population", thus supplemented and developed the breaking point theory. Then taking Yichang city as an example, the paper shows its rationality of city function localization in times of new traffic environments.