Comparative Study on Continuous and Descrete Spatial Assignment Model for Metropolitan Area

点击翻译按钮获取中文摘要

The current discrete transportation network models, which determine traffic flow on every link of a transportation network, are rather inapplicable to dense and large urban road network because of the huge amount of computational work involved. In this study we adopt a continuous approach to approximate a highly dense network and consider the traffic assignment model based on the assumption of continuous traffic flow distribution over the urban area. Two types of models are presented containing both theoretical and applied analysis of the continuous approach.First, a theoretical model, complete with an efficient computational algorithm, is constructed by using constrained variational theory and FEM technology. Distinguished from the previous approaches, this model deals with the user-equilibrium assignment with a single trip origin and continuously distributed trip destinations.With the intention of complementing the theoretical approach, a continuum approximation model is also proposed for computing the generalized traffic flow distribution over the urban area. This model is demonstrated to be efficient for the large-scale traffic assignment.The continuum models presented in this study are numerically tested with hypothetical data. The computational results coincide with the expected behavior of the proposed models.