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A Gradient Approach for the O-D Matrix Adjustment Problem

出版	Université de Montréal, Centre de recherche sur les transports, 1990
URL	http://books.google.com.hk/books?id=omyswgEACAAJ&hl=&source=gbs_api

註釋In the past, many different models using observed link volumes to estimate or adjust O-D matrices were proposed, but using them for real size networks is difficult because of the complexity of the computations involved and the need for very specialized software to carry them out. This paper presents a new gradient model which can and has been applied to large scale networks. Mathematically, the model is formulated as a convex minimization problem where, by following the direction of the steepest descent, it is ensured that the original O-D matrix is not changed more than necessary. The paper shows how this demand adjustment model can be implemented without the need to develop any new software, by using existing features of a standard transportation planning package (EMME/2). The model has been used successfully in urban and national scale projects in Switzerland, Sweden and Finland, using networks with up to 522 traffic zones and 12,460 links, results of which are given.