Comparing idle times of public bicycles in Beijing's free-floating and Seoul's dock-based systems

Abstract

The idle times of shared bicycles are primarily influenced by supply and demand dynamics. Prolonged idle periods indicate oversupply or low demand, leading to inefficient resource use, aesthetic issues, pedestrian obstructions, and increased risks of vandalism. Shorter idle periods may cause bicycle shortages, diminish service quality, and reduce overall demand. This study analyzed the unused shared mobility characteristics of 1,740,947 trips from Beijing's free-floating public bicycles and 71,778 trips from Seoul's dock-based public bicycles. Mixed-effects Cox proportional hazard models were employed to identify key factors influencing the hazard ratio of unused bicycles, modeling the time-to-event duration while accounting for the clustered structure of bicycle return locations as random effects. The modeling results indicated that, compared to the free-floating system, the hazard ratio of unused dock-based bicycles is more influenced by the characteristics of bike return locations, as suggested by the greater variance of the random parameter for the Seoul data. Residential areas were found to increase the hazard ratio of unused bicycles in both systems, suggesting oversupply or low demand. Cycling-friendly roads negatively impacted the likelihood of unused bicycles. Specifically, raised-buffered bike lanes, separated from car traffic by safety bollards, significantly reduced the probability of idle dock-based bicycles. Increased distances to district centers and subway stations had a more pronounced effect on idle dock-based bicycles compared to the more flexible free-floating bicycles. These findings offer key insights into mobility patterns and built environmental influences, aiding policymakers and urban bike-sharing operators. © 2025 Elsevier B.V., All rights reserved.