Browsing by Author "Fernandez, J. Enrique"
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- ItemCombined models with hierarchical demand choices: A multi-objective entropy optimization approach(TAYLOR & FRANCIS LTD, 2008) De Cea, Joaquin; Fernandez, J. Enrique; De Grange, LouisThis article proposes a multi-objective optimization approach to the formulation of a number of equilibrium problems that typically arise in the transportation planning process. These fall into two classes: combined demand and network equilibrium problems, the latter here called performance-demand equilibrium problems. The demand formulations are based on entropy maximization while the network equilibrium designs are modelled on Wardrop's first principle. Both are fully compatible with models based on random utility maximization (multinomial and hierarchical logit). Given the entropy-maximization aspect of the demand models and the use of symmetric cost functions in the networks, the multi-objective formulations yield classical single-objective convex optimization programs. In the past, many such problems have not been obtained deductively, their derivation being based rather on previous knowledge and the modeller's intuition. Of particular interest, therefore, is the simple deductive method presented here for formulating new problems, one that can accommodate new choices such as departure time and transfer point for combined modes. This novel approach also facilitates a better interpretation of the model parameters. In addition, we suggest a calibration procedure that permits consistent estimation of the proposed model's parameters.
- ItemPrivatisation and deregulation of urban bus services: An analysis of fare evolution mechanisms(UNIV BATH, 2007) Fernandez, J. Enrique; Munoz, Juan CarlosUrban bus systems have been privatised and deregulated in Britain, Santiago (Chile) and Colombo (Sri Lanka). Although similar regulations were applied in these cases, the outcomes observed were significantly different. We create an analytical model to explain such outcomes considering differing compositions of the bus fleet (number of operators competing and their frequencies of service) and passengers' valuation of time. We conclude that perfect competition is not likely to emerge in the urban bus market. However, while in some cases this economic distortion scarcely affects the results, in others it does so significantly. Our model accurately predicts the outcomes observed.