An intertwined triple-bottom-line rating system for highway sustainability in developing countries

Highway sustainability evaluation is a crucial step towards ensuring that transportation infrastructure meets the environmental, social, and economic needs of societies. While previous studies have developed frameworks for the sustainability performance of highway projects, they did not comprehensively address all sustainability aspects, nor stages of these projects. Furthermore, the Sustainable Development Goals (SDGs) related to highways were almost overlooked in most previous studies and infrastructure rating systems. Thus, this study introduces a rating system (RS) that encompasses the most significant factors influencing highway sustainability in Egypt across the three sustainability dimensions. These factors were identified through a comprehensive analysis of previous studies, SDGS, and existing infrastructure rating systems. A questionnaire survey was designed to assess the impact of various factors on highway sustainability. Statistical analyses were carried out to summarize data into a smaller set of factors, identifying 18 factors that were weighted using the analytic hierarchy process method. This model was then applied to real-life case studies in Egypt, and the results were compared with the Envision RS. The results' convergence confirmed the validity of the developed RS, which features fewer factors and a more user-friendly interface. Finally, the developed RS was reviewed by highway experts and environmental consultants to assess its performance and gather their recommendations. The developed RS presents a summary report that identifies shortcomings in achieving the target score and offers guidelines to enhance the sustainability score. Also, it addresses the shortcomings found in other RSs, providing a more balanced approach across the investigated sustainability dimensions.