Mode-specific impacts of social distancing measures on the intra- and inter-urban mobility of public transit in Seoul during the COVID-19 pandemic

Social distancing measures (SDMs) mitigated the spread of coronavirus disease 2019 (COVID-19) by reducing human activity and mobility. However, few studies have explored SDMs’ effects on intra- and inter-urban mobility concerning public transit. This study employed the autoregressive integrated moving average with exogenous variables models to examine distinct-level impacts of SDMs on intra- and inter-urban daily ridership by transit in Seoul, South Korea, during the COVID-19 pandemic. This study found: (1) The effect of SDMs on transit mobility was more pronounced for subways than buses, despite both modes experiencing reduced mobility without completely ceasing operations. (2) No substantial disparity was observed between intra- and inter-urban transit mobility. (3) Although other measures effectively curtailed transit mobility, mask-wearing had no statistically significant impact on intra- and inter-urban transit usage. (4) Heightened SDMs (e.g., workplace closures, cancelation of public events, stay-at-home orders) have reduced transit mobility more for railways/subways than buses. These findings underscore the importance of considering the distinct impacts of diverse SDMs on transit mobility, thereby ensuring the sustainable functioning of public transit while mitigating the spread of infectious disease during pandemics