Realizable accessibility: Evaluating the reliability of public transit accessibility using high-resolution real-time data

New paper: Liu, L., Porr, A. and Miller, H.J. (2023) “Realizable accessibility: Evaluating the reliability of public transit accessibility using high-resolution real-time data,” Journal of Geographical Systems, 25, 429-451.

Abstract. The widespread availability of high spatial and temporal resolution public transit data is improving the measurement and analysis of public transit-based accessibility to crucial community resources such as jobs and health care. A common approach is leveraging transit route and schedule data published by transit agencies. However, this often results in accessibility overestimations due to endemic delays due to traffic and incidents in bus systems. Retrospective real-time accessibility measures calculated using real-time bus location data attempt to reduce overestimation by capturing the actual performance of the transit system. These measures also overestimate accessibility since they assume that riders had perfect information on systems operations as they occurred. In this paper, we introduce realizable real-time accessibility based on space–time prisms as a more conservative and realistic measure. We, moreover, define accessibility unreliability to measure overestimation of schedule-based and retrospective accessibility measures. Using high-resolution General Transit Feed Specification real-time data, we conduct a case study in the Central Ohio Transit Authority bus system in Columbus, Ohio, USA. Our results prove that realizable accessibility is the most conservative of the three accessibility measures. We also explore the spatial and temporal patterns in the unreliability of both traditional measures. These patterns are consistent with prior findings of the spatial and temporal patterns of bus delays and risk of missing transfers. Realizable accessibility is a more practical, conservative, and robust measure to guide transit planning.

Why buses can’t get wheelchair users to most areas of cities

New publication: Liu, L., Kar, A., Tokey, A. Le, H.T.K. and Miller, H.J. (2023) “Disparities in public transit accessibility and usage by people with mobility disabilities: An evaluation using high-resolution transit data,” Journal of Transport Geography, 109, 103589.

Abstract: Many people with mobility disabilities (PwMD) rely on public transit to access crucial resources and maintain social interactions. However, they face higher barriers to accessing and using public transit, leading to disparities between people with and without mobility disabilities. In this paper, we use high-resolution public transit real-time vehicle data, passenger count data, and paratransit usage data from 2018 to 2021 to estimate and compare transit accessibility and usage of people with and without mobility disabilities. We find large disparities in powered and manual wheelchair users’ accessibility relative to people without disabilities. The city center has the highest accessibility and ridership, as well as the highest disparities in accessibility. Our scenario analysis illustrates the impacts of sidewalks on accessibility disparities among the different groups. We also find that PwMD using fixed-route service are more sensitive to weather conditions and tend to ride transit in the middle of the day rather than during peak hours. Further, the spatial pattern of bus stop usage by PwMD is different than people without disabilities, suggesting their destination choices can be driven by access concerns. During the COVID-19 pandemic, accessibility disparities increased in 2020, and PwMD disproportionately avoided public transit during 2020 but used it disproportionately more during 2021 compared to riders without disabilities. This paper is the first to examine PwMD’s transit experience with large high-resolution datasets and holistic analysis incorporating both accessibility and usage. The results fill in these imperative scientific gaps and provide valuable insights for future transit planning.


Electric, Autonomous, & Green: The Future of Personal Transportation – Columbus Metropolitan Club – May 3 2023

On Wednesday, May 3 2023, I had the opportunity to participate in a panel discussion on the Future of Personal Transportation at the Columbus Metropolitan Club. Joining me on the panel were Preeti Choudhary, Executive Director, DriveOhio, Ted Angel, Director, Aerospace Affairs, Dayton Development Coalition, and  host Walker Evans, Co-Founder & CEO, Columbus Underground.

My main message – the future of personal transportation should be similar to the history of personal transportation – walking, biking and public transit. Electric vehicles, autonomous vehicles and advanced air mobility are simply continuations of the same thing we have been trying for a century – cars and car dependence.  As should be clear, cars are not working well, and we can’t solve our car problem with more car-ing.

Event Page

Video of the panel discussion