A multiple mediation analysis to untangle the impacts of COVID-19 on nationwide bus ridership in the United States

The COVID-19 pandemic has resulted in major consequences for many aspects of human life and the broader economy. Many transportation modes were severely impacted, including public transportation. During the early months of the pandemic in 2020, transit ridership dropped to unprecedented levels. Even by the end of 2022, bus ridership in the United States had not recovered to pre-pandemic levels. Despite the longstanding effects on public transportation, the direct and indirect impacts of the COVID-19 pandemic on bus ridership are largely unknown. In the context of this study, the direct impact refers to a change in travel behavior (i.e., due to the increased spread of COVID-19), while the indirect impact refers to reduced ridership due to factors such as lower employment or increased teleworking. This study proposes a framework to explore the drivers of transit ridership declines during COVID-19. The method is a multiple mediation analysis to estimate the monthly direct and indirect impacts of COVID-19 on bus ridership from March 2020 to December 2021. The results of this study revealed that three mediators (employment, telework, and people relocating) mediated about 13% to 38% of the total decline in bus ridership during the analysis period. The multiple mediation approach used in this study could be applied in many other transportation applications.