Browsing by Author "Fernandez, Enrique"

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    A consolidated model of trip distribution
    (PERGAMON-ELSEVIER SCIENCE LTD, 2010) de Grange, Louis; Fernandez, Enrique; de Cea, Joaquin
    This work analyzes and compares various trip distribution models with spatial aggregation within a common theoretical framework for formulating and solving multi-objective optimization problems. A new model is designed that incorporates the main characteristics of existing ones. These models are then calibrated with a single database at different spatial aggregation levels using maximum likelihood. The results show that with aggregated data the various models differ little, but with disaggregated data the differences are considerable. It is also demonstrated that changing the level of data aggregation can significantly alter the models' parameter values. (C) 2009 Elsevier Ltd. All rights reserved.
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    Combined Model Calibration and Spatial Aggregation
    (2010) de Grange, Louis; Fernandez, Enrique; de Cea, Joaquin; Irrazabal, Magdalena
    A methodology is proposed for estimating a combined transportation model that accommodates spatial aggregation. It employs maximum likelihood estimation using a joint probability function that includes destination and mode choice simultaneously. The main contribution of the paper is the incorporation of a spatial aggregation strategy to validate the method when the survey data are insufficient. By aggregating small zones into larger districts, estimation of the trip distribution parameters can be achieved with limited data, while mode choice continues to be estimated using disaggregated data. Our results demonstrate that including trip distribution in the travel decision induces variations in the utility function parameter estimators obtained for the different travel modes when only mode choice is estimated. The methodology thus corrects omission bias.