Simultaneous estimation of an origin-destination matrix and link choice proportions using traffic counts

A procedure for the simultaneous estimation of an origin-destination (OD) matrix and link choice proportions from OD survey data and traffic counts for congested network is proposed in this paper. Recognizing that link choice proportions in a network change with traffic conditions, and that the dispersion parameter of the route choice model should be updated for a current data set, this procedure performs statistical estimation and traffic assignment alternately until convergence in order to obtain the best estimators for both the OD matrix and link choice proportions, which are consistent with the survey data and traffic counts. Results from a numerical study using a hypothetical network have shown that a model allowing [theta] to be estimated simultaneously with an OD matrix from the observed data performs better than the model with a fixed predetermined [theta]. The application of the proposed model to the Tuen Mun Corridor network in Hong Kong is also presented in this paper. A reasonable estimate of the dispersion parameter [theta] for this network is obtained.