Helping decision-makers select the most adequate road infrastructure design from the point of view of sustainability: a practical approach

Abstract

In recent years, a number of tools have been developed aimed at assessing the socio-economic and environmental feasibility of roadway projects. However, there is still no standardised or commonly accepted methodology to assure the most sustainable design in the appraisal and evaluation of roads over their life-cycle. The introduction of the multidimensional perspectives of sustainability in the appraisal of road projects is still an unresolved aspect. This research identifies strengths and weaknesses of sustainability assessment tools ?including ratings systems, traditional decision-making techniques (e.g. cost benefit analysis, multicriteria decision analysis, among others), checklists and different evaluation frameworks and models for roadways; describes to what extent they integrate sustainability as a whole; and summarizes valuable lessons to learn from them. On the basis of this analysis, it points out a number of methodological issues that need to be addressed before valid road sustainability assessments can be conducted. To response to these issues, this research develops a composite decision support model based on combining cost-benefit analysis (CBA) with multi- criteria decision analysis (MCDA) to accurately appraise sustainability of road projects. This methodology is applied to a case study dealing with the construction of a new roadway in the northwest of Spain. The outcome demonstrates that the approach is a valuable sustainability assessment tool