This study analyzed the operation-related historical data of the call taxi service for disabled people in Seoul, South Korea. The study investigated how unevenly distributed the accessibility of disabled people to transportation is in terms of time and space. In addition, the reasons that cause imbalanced accessibility were investigated in areas with good and poor accessibility. Accessibility was defined as how quickly call taxi services for the disabled are available at specific times and locations. For the analysis, the log data for tracking the status of taxis in time and space were processed to calculate their availability, an index that reflects the dwelling time and the number of taxis available at a specific time and in a specific area. This index was divided into time and space and used as a surrogate measure to assess accessibility. The results showed that there were spatial and temporal accessibility imbalances in demand responsive transit (DRT) service. The insufficient supply during the night resulting from the current DRT operating schedule has reduced the accessibility of call taxis for the disabled, and the concentration of drivers’ breaks also affected the accessibility of service during the daytime. This suggests the need for (1) an increase in supply and (2) evenly distributed breaks for the drivers. In terms of space, the outer areas of Seoul generally were found to be more accessible than the central areas. In addition, areas near depots that serve as hubs and resting places for taxi drivers, areas with excellent medical infrastructures for people with disabilities, and areas with good traffic environments tended to have good accessibility; this suggests the need to reallocate garages and improve the traffic environments to improve accessibility.

The importance of Demand Responsive Transport (DRT) has increased as it guarantees the right to travel and improves mobility for special population groups such as disabled people and low income households. In order for DRT to become a sustainable means of transportation, it is necessary to keep the quality of DRT service above a certain level that might be expected by users, and thus DRT service needs to be provided evenly over time and space. This study aims to investigate the spatiotemporal characteristics of DRT service based on waiting time in terms of service equity. For the analysis, operating data of DRT for people with disabilities provided from the Seoul Metropolitan Government were used and a survival analysis was employed to derive median waiting time. The results showed that there exists a difference in median waiting time over time and space, indicating that DRT service for disabled is not evenly provided over time and space. The results of using a heat map and Kernel density plot with median waiting time also confirmed that the spatiotemporal imbalances of DRT service exist throughout Seoul. One of the major reasons for this phenomenon might be the uneven spatiotemporal distribution of supply as expected.

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