Revealing Structural Imbalances in Pavement Sustainability: A Scientometric and Content Analysis of Triple Bottom Line Integration (2015–2025)

Infrastructure systems play a critical role in shaping environmental performance, economic investment, and social well-being. Infrastructure systems are responsible for nearly 60% of global greenhouse gas (GHG) emissions. Pavement construction and maintenance alone consume over 350 million tons of asphalt annually and account for 30% of public infrastructure expenditure. While sustainability frameworks increasingly emphasize the integration of environmental, economic, and social dimensions commonly conceptualized as the Triple Bottom Line (TBL), their application in pavement engineering remains uneven. This study investigates the extent and nature of TBL integration in pavement sustainability research through a combined scientometric and qualitative content analysis of 529 peer-reviewed publications indexed in Scopus between 2015 and 2025. Using a PRISMA-guided review protocol, the study maps publication trends, geographic distribution, and thematic evolution, and systematically classifies each study according to its level of sustainability integration. The results reveal a pronounced imbalance across sustainability dimensions. Only 7.4% of studies achieve full TBL integration, while 45.2% address a single dimension and 29.1% remain primarily technical with limited sustainability framing. Environmental and economic dimensions are consistently operationalized through standardized methodologies such as Life Cycle Assessment (LCA) and Life Cycle Costing (LCC), whereas social sustainability appears in less than 10% of studies and is typically represented through simplified or proxy-based indicators. The findings suggest that this imbalance is not solely a result of data or awareness limitations but is associated with prevailing methodological preferences that favour quantifiable and optimization compatible indicators. These tendencies create systematic challenges for integrating context-dependent and participatory social considerations into engineering decision-making frameworks. By highlighting these structural patterns, the study contributes to ongoing discussions on sustainability governance and calls for more inclusive, methodological plural approaches to infrastructure assessment. The paper concludes by outlining pathways for advancing TBL integration through standardized social indicators, participatory assessment methods, and alignment with emerging ESG reporting requirements.