Estimation of a Time Dependent OD Matrix from Traffic Counts

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We propose the model for estimating time-dependent OD matrices from traffic counts in a general network with route choice activities.Many dynamic traffic simulation models have been developed in order to reproduce traffic conditions and evaluate policies of traffic control, signal control, one-way traffic control and so on. Such a dynamic model needs a time-dependent OD,especially one composed of small OD zones. However, it is hard to estimate OD flows directly from OD survey. In this study, we thus propose a dynamic estimator using time-dependent traffic counts to obtain time-dependent OD volumes.The model consists of two parts : (1) construction of the relationship between the time-dependent OD volumes and traffic counts at links and (2) estimation of a unique time-dependent OD matrices. In the first part, we define a three-dimensional network to relate OD matrices to traffic flow on links. We then propose a method of estimating route choice probabilities. In the second part, we employ the Entropy Maximizing method for the staic OD matrices estimation and extend it to time-dependent model. As an extension, we propose a simplified method of estimating route choice probability and a method to utilize aggregated prior OD information.At the last, we apply the model to a test network and examine its validity.