A critical overview of scientific publications on life cycle assessment in transport-related topics.

The transport sector contributes globally around 14% of the greenhouse gas emissions, and one-third to the European Union's. As an important economic sector, it requires an in-depth discussion, especially regarding environmental impacts. This paper focuses on transport-related life cycle assessment studies, as they are vital for the decision-making processes at various levels. We have framed our research on the requirements of the International organization for Standardization. We have given particular attention to the quality of life cycle assessment phases (goal and scope, inventory, life cycle impact assessment, and interpretation). We have explored 34 research and review papers, acquired from the Web of Science database. Furthermore, we have carried out a content scope analysis using Leximancer to determine and assess existing research areas and future trends. Results are represented via concept maps, giving a comprehensive overview of the life cycle assessment research in the transport. Our study indicates several incompatibilities with the standardised methodology. The findings suggest improvements in the methodological perspective. For example, system boundary represents a weakness in several studies as well as a comprehensive definition of goals or functional unit. Reliable and standardised studies are better-supporting decision-making process, leaving out any ambiguous understandings or manipulation of the results. A content analysis revealed most frequently discussed concepts, which were 'impact', 'transport', 'emissions', and 'carbon', suggesting existing research trends, and identifying research gaps, such as consumption-related topics. [ABSTRACT FROM AUTHOR]