Metodología para el análisis y selección sostenible de alternativas en infraestructuras mediante la aplicación de métodos de decisión multicriterio con criterios en conflicto y en condiciones de incertidumbre

Resum

Modern infrastructure projects require the analysis and selection of the best solution from several alternatives which are a valid solution to the problem posed. To carry out this process from a sustainable point of view, it is first of all essential to consider all the sustainability requirements that may be relevant in the project, in order to develop all the feasible alternatives that comply with these requirements. At the same time, it is crucial to determine the relative importance of the selection criteria and to assess this relative importance considering the weighting of criteria. On the other hand, the selection of alternatives usually takes place in an environment of uncertainty, which increases the complexity of the decisions to be taken. Multicriteria decision methods are tools that help in the process of selecting alternatives by providing a systematic decision-making process. The use of these methods reduces the subjectivity of the decision-maker and allows each alternative to be evaluated quantitatively, according to the set of selection criteria. However, multicriteria decision methods have certain limitations and drawbacks, among which it should be noted that most of them do not consider specifically the correlation between the variables considered in the process. For this reason, all multi-criteria decision methods are studied in a specific chapter, stating their advantages, disadvantages and main applications. This research starts by identifying the sustainability criteria involved in the process of selecting alternatives, and then continues with the study, application and development of a decision methodology based on the determination of proximity (shortest distance) to the socalled "ideal solution", understood as a fictitious solution which performs best for each decision criterion. The aim is to determine the alternative whose mathematical distance to the ideal solution is the smallest possible, and to obtain a ranking of alternatives according to this distance, ordered from the shortest to the longest distance to the ideal solution. To consider the correlation between variables- in the process, a decision methodology is proposed based on the concept of distance to the "ideal solution", measured through the Mahalanobis distance, which has the particularity that, in addition to considering the correlation between variables, it is invariant to scale. Thus, the proposed methodology consists of a modification of the VIKOR multi-criteria decision method by applying the Mahalanobis distance to calculate the values of S or R variables of the traditional VIKOR method. Any methodology based on a multicriteria decision method must be verified using both a robustness and a sensitivity analysis, in which the former will determine the validity of the model so that the optimal solution is indeed optimal among a given set of solutions. The latter sensitivity analysis aims to study and discover the degree of sensitivity of the optimal solution to changes in the essential factors or criteria. To analyze the stability of the solutions provided by the methodology developed, a sensitivity analysis is carried out, consisting of modifying the initial weighting of the selection criteria and determining the number of changes that occur in the ranking of alternatives and, in this way, determining the criterion with the highest relative sensitivity coefficient. Finally, the original proposed methodology is applied to the selection of alternatives for two different infrastructure types. First, to the selection of best alternative for retaining wall typologies in linear infrastructures, due to the considerable environmental impact they have on the surroundings, both visually and as a barrier. Second, to the selection of the optimal location of park and ride infrastructures, as they are a key infrastructure in urban mobility plans and in the establishment of traffic restriction measures in city centers of large metropolitan areas, when seeking to reduce pollutant gas emissions.