Causal Impacts of the Coronavirus-19 Pandemic on Daily Ridership of Public Bicycle Sharing in Seoul

During the COVID-19 pandemic, the private bicycle can be a disease-resilient travel mode. However, the public bicycle may not be one, especially in densely populated cities, due to the more risk of its infection, and few studies have focused on which factors affected change in its daily ridership during the pandemic. Therefore, this study used Bayesian structural time series models and causal impact inference for the data on the daily ridership of public bikes in Seoul, South Korea, for1826 days from January 1, 2017, to December 31, 2021. The results of the study demonstrated that the usage of public bikes was robust against the Coronavirus-19 pandemic even in densely populated Seoul. Compared with the pre-pandemic period, public bicycles’ usage was unaffected on days when weather conditions, such as snow, rain, and wind speed were not as severe, as well as on days with non-seasonal event factors, such as weekdays, public holidays, and traditional Korean holidays. In addition, its robustness against the pandemic became more pronounced as the number of bicycle racks increased and the intensity of social distancing increased. However, public bikes were in demand primarily for leisure and exercise, not for travel, during the pandemic. Therefore, continuous investment in infrastructure, such as bicycle paths, is required to become a more resilient travel mode against infectious diseases.