Collective and individual spatial equity measure in public transit accessibility based on generalized travel cost

This study devises a novel two-dimensional analysis framework for spatial equity in public transit accessibility. We incorporated door-to-door travel time and ticket price by public transit into a generalized travel cost function to measure utility-based accessibility following a log-sum formulation. Then, this study designed a Palma ratio of accessibility and a neighboring accessibility gap index to respectively examine the collective spatial equity and individual spatial equity of public transit. Finally, we took an empirical case of Kunming city, China to analyze the unity-based accessibility distribution and checked collective and individual spatial equity levels reaching business centers, transport hubs, and 3-A hospitals. The results show that the utility-based accessibility reaching transport hubs by public transit is less than 50% to business centers and 32% to 3-A hospitals. Collectively, the expected minimum generalized travel cost by public transit in the poorest 40% of traffic analysis zones is almost 2.5 times as much as in the richest 10% of traffic analysis zones, and the collective spatial equity in old blocks is superior to new blocks. Individually, the number of traffic analysis zones with no spatial inequity, slight inequity, and medium inequity in public transit accessibility respectively occupied almost 57%, 38%, and 5%. We also found individual spatial equity may be associated with the walking distance during taking public transit and the number of neighboring traffic analysis zones.