Towards Sustainable Roads: A Systematic Review of Triple-Bottom-Line-Based Assessment Methods

This review summarizes the methods and approaches for quantifying the sustainability performance of roads based on the Triple Bottom Line (TBL) concept. Furthermore, research gaps and challenges in the sustainability assessment of roads are identified. While prior studies explored the environmental and economic dimensions, no comprehensive overview of holistic sustainability assessment of roads exists. A systematic literature review (SLR) was conducted to identify relevant studies. Two assessment approaches were identified: (1) life-cycle-based approaches and (2) sustainability rating systems (SRS). Most of the reviewed studies applied life-cycle-based methods, such as Life Cycle Sustainability Assessment or a combination of Life Cycle Assessment, Life Cycle Costing, and selected social indicators. Heterogeneity in functional units was observed, with most studies opting for a dimension-based instead of a function-based reference. There was high variability regarding the life cycle stages, indicators, and impact assessment methods. Concerning the interpretation methods, most studies calculated a sustainability index or applied Multi-Criteria Decision-Making methods. The SRS presented a similar structure with different levels of aggregation. Furthermore, aspects such as planning, leadership, innovation, and construction activities were addressed. The results of this SLR contribute to expanding the knowledge regarding road sustainability and provide insight into common frameworks, guidelines, and best practices for the sustainability assessment of roads and pavements.