Who needs public transit to evacuate? A national household survey insight

Abstract: Disasters, whether natural or human-made, have long posed significant threats to people's lives. In such emergencies, transportation plays a crucial role in evacuating individuals from at-risk areas. Public transportation systems are particularly effective in evacuating transit-dependent and vulnerable populations. This study aims to investigate public transit needs for evacuation during emergencies in the United States by analyzing three years of household survey data collected by the Federal Emergency Management Agency (FEMA). Random forest models were developed to model the public transportation needs among surveyed participants across three years. Feature importance, partial dependence plots (PDPs), and Shapley values were employed to understand the relationship between independent variables and public transportation needs. The analysis results indicate that about 20% of respondents require public transportation for evacuation each year. Key factors that shape or are associated with this need include the primary language spoken, homeownership status, confidence in taking preparatory steps, and the FEMA region. PDPs and Shapley values revealed that several features, such as lower confidence in emergency preparation, minority ethnicity, elderly age, low income, renting a home, non-English speaking households, low education levels, residence in FEMA Region 2, and being affected by floods, were positively associated with the need for public transit during evacuations. The findings are expected to provide valuable insights for developing local public transit evacuation plans that incorporate the socio-demographic features of people.