Equity and accessibility assessment of fixed route transit systems integrated with on-demand feeder services

In contemporary societies, public transportation holds paramount significance for fostering sustainable and equitable urban development. Concurrently, innovative mobility solutions, such as the integration of on-demand mobility services like Demand Response Transit (DRT) and Transportation Network Companies (TNC) with Fixed Route Transit (FRT) systems, are gaining prominence. On-demand mobility, with its adaptive dynamic routing, can improve public transit access by best utilizing the existing infrastructure. However, to ensure the adequacy of the service of an integrated system, it is essential to evaluate equity and accessibility of the system. While research has explored the adaptability of integrated multi-modal transport systems, a critical gap remains in understanding the impact on transportation accessibility, particularly for transit-reliant communities. This study utilizes spatial indicators to depict accessibility changes at FRT bus stops post-integration with on-demand services. To assess the enhancement in accessibility resulting from integration, the study employed an agentbased model, testing two scenarios: i) Walking with FRT and ii) On-demand Feeder with FRT (DRT and TNC integrated as feeders). The evaluation employs key metrics, including Transit Coverage Gap, the Lorenz curve, and the Gini index, to analyze the accessibility and equity of the integrated services. Additionally, a novel measure, termed the "Accessibility-Radius," is proposed to quantify spatial accessibility to FRT services. AccessibilityRadius (AR) is defined as the radial service range of a public transit stop, which captures the dependence of the users of the FRT stop to access the public transit facilities. In this study, we quantified the AR as the 90th and 95th percentile distances between various origins and the nearest FRT stops of completed trips. The results of a case study of the city of Morristown, Tennessee, US, indicate that after integration, the Gini index improved from 0.88 to 0.71, and 29.6 % more people had access to public transportation. The study also utilizes the AR performance metric to evaluate a recently developed transit integration project in Memphis, Tennessee, US. The results demonstrate a remarkable 224 % improvement in transit coverage Gap at an FRT stop. Therefore the contribution of this study is a framework to evaluate the accessibility and equity enhancement for a public transit system after integrating with on-demand feeder services.