Assessing the Sustainability of Transport Systems through Indexes: A State-of-the-Art Review

The transportation sector significantly impacts economic development; however, its sustainability is challenged, particularly due to the increase in urban vehicle numbers and the associated negative consequences. In response, diverse evaluation methods have been introduced to assist decision-makers in assessing sustainability, accompanied by the development of numerous indicators to monitor the progress of sustainable transport systems. Consequently, the evaluation of the transport system has become crucial. This study conducts a comprehensive literature review on existing approaches used to assess transport sustainability through composite indicators. The analysis began by selecting articles using keywords like "sustainable transport", "sustainability indicators", "composite index", and "assessment". Subsequently, 61 relevant articles were identified, and only 47 studies from the period 2002-2022 were selected. The analysis was completed by synthesizing the literature and presenting the findings. The examination of literature trends revealed a limited focus on freight transport, with most studies concentrating solely on traditional sustainability dimensions. Additionally, the analysis highlighted the significant impact of various normalization, weighting, and aggregation methods on composite indicator results. Finally, recommendations for precise sustainability assessments are provided to guide future research endeavors.