Modelo acoplado de demanda, oferta dinámica y coste generalizado orientado a la evaluación ex-ante, bajo condiciones de incertidumbre, de proyectos alternativos de sistemas de transporte metropolitano de capacidad intermediatranvía o metro ligero (LRT) frente a autobuses semirrápidos (BHLS o BRT)

Abstract

The major purpose of this PhD Thesis is the design, development, computational implementation and execution of a transport model specifically devised for the forecasting of the effects that would be generated by the hypothetical introduction ― into a corridor, axis or route with given characteristics ― of each one of the two main types of urban and metropolitan middle-capacity transit systems. Such effects are quantitatively reflected in the model by a set of variables indicative, among others, of trip volumes and travel conditions. For this analysis, the two main classes of middle-capacity transit systems are the light rail modes (LRT and/or modern tramway) and the bus semirapid transit systems with exclusive right-of-way, commonly termed as BHLS (Bus with High Level of Service) or BRT (Bus Rapid Transit). The proposed analytical model systematizes the interdependencies between several processes such as the travel demand prognosis (for the public transit mode and also for other possible modal options), the dynamic characterization of the modal supply’s attributes, the valuation of each one of the modal options by the travelers (by means of the generalized cost concept), and the estimation of the aggregated choices of such travelers (modal split and effects on the total trips volume). In these analyses, a detailed treatment is given to the modeling of the different public transit systems’ opera-tions, as well as to the prediction and valuation of their attribute-variables, combined into their generalized travel cost. Furthermore, the model is designed in order to forecast the future evolution of the relevant transport-related variables over the years of a certain appraisal period. Consequently, the model results serve as a fundamental input for a right ex-ante (i.e. prospective) socioeconomic assessment of the possible implementation and selection of one of these two types of urban and metropolitan middle-capacity transit systems. In addition, the model development has incorporated the methodological treatment of the related uncertainty, linked to the data or input variables as well as to the modeling process. Such uncertainty is methodologically treated by means of the implementation of multiple random simulations with values drawn from the probability distributions of the appropriate variables, applying thus the Monte Carlo method. Finally, the model functioning is tested and put into practice by applying it to a calculation example that is based on a set of artificial data. Such data have been specially designed to be illustrative of fairly usual conditions in corridors, axes or routes with intermediate volumes of public transit demand. However, the results obtained for this example, as well as the conclusions derived from it, are of specific application to the data set of this particular case (or to others as much as they be relatively similar), so such results and conclusions should not be immediately overgeneralized or extrapolated to any other conditions. To conclude, the results of this example are thoroughly analyzed, and a balance of the increase in the travelers’ surplus or benefit against the start-up investment costs is finally obtained as a proxy-value to pre-estimate, in a case like this, the possible socioeconomic performance of the middle-capacity transit systems and the comparative appraisal of their two main types.