Public Transportation and Social Sustainability: Investigating the Use of Indicators to Evaluate Social Sustainability in Public Transportation Systems

59 pagesFor the last 30 years, countries across the world have grappled with how to advance people’s quality of life given increasing risks to daily life posed by a changing climate. Among our understanding of the drivers of climate change, the transportation sector in particular exists as a primary source of greenhouse gas emissions and must be reformed to achieve a sustainable society. In recent years, a renewed interest in promoting sustainable transportation has driven sizeable government expenditures, notably as part of the Infrastructure Investment and Jobs Act (IIJA) in the United States. Recognizing the urgency with which large sums of public funds are allocated toward transforming the U.S. transportation system, it is important to possess a means of evaluating if such investments produce the desired outcomes. This project examines one component of sustainability evaluation in the context of public transportation systems. Public transportation is an essential service for millions of individuals on a daily basis to access employment, education, healthcare, basic amenities, and social interactions. However, in striving to make transportation systems sustainable, policymakers and researchers alike often focus their attention on the environmental and economic aspects of sustainability. The social aspect of sustainability and how to evaluate it is much less researched. I examine the literature published about social sustainability and the proposed approaches to assessing it in public transportation systems. Using a mixed-methods approach, I employ a science mapping analysis to build a visualization of different indicators meant to measure characteristics of social sustainability within public transportation. From this map, I perform a content analysis to distinguish indicators that are clear in their prescribed measurement and analyze the structure of how indicators relate to themes. This analysis assesses how useful current evaluation methods for identifying social sustainability in systems are for today’s transit providers and researchers. Based on the analysis, I find that social sustainability is especially complex, compromised of over a dozen themes that each possess a number of associated indicators. Although some indicators prescribe a clear measurement, many others lack specificity in what the indicator measures or how to carry out that measurement and can vary in meaning based on the geographic scale selected for assessment. Furthermore, existing models evaluating social sustainability in transportation often fail to assess aspects of the transportation system that most affect vulnerable populations, including people living with disabilities. From these findings, I argue that a comprehensive review of existing indicators to provide clear measurements and develop new indicators to account for gaps in assessment of social sustainability is needed to give policymakers and researchers a functional tool for ensuring that sustainability plans address each of the major pillars: environmental, economic, and social. Ensuring balance between these priorities will ensure large investments to reform public transportation systems do not achieve sustainability through environmental and economic objectives at the expense of social outcomes