Multikriterie beslutningsanalyse i broprosjektering med forskjellige fremgangsmåter

Abstract

In this thesis, the topic of multi-criteria decision-analysis in bridge design processes was explored. It had been discovered that this could be done using two different approaches to modelling a decision problem. Using the software DecideIT, the same decision problem with the same inputs for both approaches was modelled, and the outcomes of these models were evaluated. It was concluded that even though the models were not faultless in terms of decision-making accuracy, some significant findings related to the nature of how the two approaches reaches their outcomes were found, and that these would not be influenced significantly by the inaccuracy of the performance scores themselves. It was found that even though both approaches reached the same conclusion in terms of which combination of structural system and material would be recommended for the case in question, they gave different impressions of the degree of dominance within these two individual selections. The second approach, modelling the selections separately before combining the outcomes in a feasibility study, gave clearer preferences for the selection of structural system and the selection of material. While the first approach, modelling both selections in one model, had the advantage of handling the combination of the separate selections in a simple and accurate way, something that can be difficult with possibility for inaccuracies when using the second approach. No attempt was made to reach a conclusion as to which of these approaches would be objectively better as they were found to have their individual strengths and weaknesses, but the findings of this thesis can be helpful for future decision makers in keeping mindful of how the outcomes could change based on the choice of approach. Recommendations about the need for future research was also made, arguing that there is a need for more research on the topic in general, as well as further research within the themes of this thesis.