Study On The Methods For Routing Traffic Flows Based On The Data Of Expressway Network Tolling System

Route flows solution of the traffic assignment problem is not only the importantparameter of the traffic planning analysis, but also the key point to the multipath problems,such as the ambiguous path problem. Therefore, the methods to get the route flows havealways been the hotpot and focus of the traffic assignment research.Traffic assignment methods are divided into two broad categories according to theWardrop principle. One is not consistent with the principle and the other one is opposite.Logit method belongs to the former one and had received a wide publicity in the past decadesbecause it can analyse the dynamic travel choice behavior of travelers. Method of successiveaverages (MSA) is also a common method belongs to the former category. It considerates theeffect of link flows on link impedance based on the Logit method. The later category gets thelink flows and route flows through solving a traffic assignment model. The algorithms to thismodel can be devided into three kinds-link-based algorithms, route-based algorithms andorigin-based algorithms. F-W algorithm is the most typical and widely used link-basedalgorithm. Route-based algorithms are uncommon used because they need large memory tostore the routes and apply only to the small-scale networks. Origin-based algorithms areessentially route-based, but they improve the disvantages of the route-based algorithmsthrough removing the cycle structures. The Origin-based algorithm has attracted a lot ofattention in recent years, and on the basis of it Bar-Gera proposed the TAPAS algorithm. Itintroduced the notion of PAS and flows on the active PASs are redistributed between originsaccording to the proportionality condition to ensure the uniqueness of route flows sloution,that is to say the stable route flows can be got under the porpotionality condition.This paper studies the effciency of several typical methods for route traffic flows basedon the data of expressway network tolling system, and proposes the link impedance functionwhich suitable to the expressway. Besides, the paper also examines he stability of theporportionality condition according to the real route flows.