Estimation of Social Return on Investment in Regional Public Transportation of a Japanese Suburban Area

抄録

In many developed countries, the sustainability of public transportation has become a pressing issue particularly in suburban areas due to declining demand caused by population decrease and a shortage of drivers. This study applies Social Return on Investment (SROI) - a framework to promote stakeholder participation and mobilize resources—to public transportation and proposes an evaluation method for transportation in an era of decline. We focused on a community bus service introduced in a suburban area of Japan. A Theory of Change (ToC) was developed, and a questionnaire survey was conducted with support from a resident-led preparation committee. A total of 402 responses were collected, capturing perceived social, environmental, and economic impacts. We proposed an extended methodology for SROI that links the ToC conceptual framework with the SEM analytical framework. Using financial proxies from previous studies, the SROI was estimated at 26.2, indicating justification for investment in the community bus service.