Study on spatial distribution and inequity of rail transit travel accessibility under multi modal traveling: A case study of Beijing

In order to promote the development of the basic public service system, it also needs to enhance the affordability and fairness of surrounding communities of rail transit stations. Based on this, the example for this research has been selected as the area within the 6 th Ring Road of Beijing. This paper is aimed at finding out the difference between the openness of the environment around the rail transit station and the population density. This simulation and examination on rail transit station regions' accessibility employed the Gaussian-based two-step floating catchment area approach and the Gaode Map service Application Programming Interface (API) four transport modes: walking, cycling, driving a car, and taking public transport. By combining the calculation results with population distribution data, the current state of accessibility equity is assessed. The IPA analysis method is employed to determine the priority order for different area modifications and to propose corresponding suggestions for optimization. The findings are as follows: (1) Within the urban core and urban sub-center area, accessibility is higher compared to other regions across different travel modes; (2) Within the study area, there is a significant positive correlation between the accessibility of rail transit station areas and the travel mode; (3) Within the maturely developed areas, there are notable differences in the equity and accessibility of rail transit station areas across different travel modes. According to the Gini coefficient, accessibility is most equitable when traveling by car or bicycle, and least equitable when traveling on foot or by public transit; (4) Local bivariate spatial correlation analysis indicates that cycling and driving can improve the accessibility equity within the urban core compared to walking and public transit; (5) Importance-Performance Analysis (IPA) results show that the area from western fringe area of the urban core has the highest priority for redevelopment, and the accessibility equity northern fringe of the city can be improved by promoting cycling to enhance accessibility of walking and public transit. The findings of this study can be applied to urban rail transit accessibility improvement projects.