Evaluation of public transportation network equity in low-density areas: a case of Lanzhou

With the increasing urban-rural differences in China, rural public transportation systems in low-density areas face distinctive challenges, including dispersed population, complex topography, and uneven public-service allocation. Taking the rural areas surrounding Lanzhou as a case study, this research applies network-topology analysis to examine the connectivity and structural characteristics of the public transportation network. By integrating station accessibility, per-capita accessibility, and Gini coefficient decomposition, we evaluate the efficiency and distributive equity of rural public transportation in the region. In this study, equity is operationalized from an egalitarian perspective, namely the extent to which per-capita accessibility is equally distributed across administrative units. The results show: (1) the rural bus station network in Lanzhou has low connectivity, few key hub nodes, and weak urban-rural transport integration; (2) transportation accessibility exhibits a ‘central-high, east-west-low’ spatial pattern, with accessibility values ranging from 78.04 to 0.02; (3) substantial service gaps remain, with 34.7% of the study area uncovered; and (4) the overall Gini coefficient is 0.735, indicating severe inequality in per-capita public transportation accessibility, especially along the county-village dimension. This study provides empirical evidence for optimizing public transportation systems in low-density areas and offers a methodological reference for urban-rural integrated transport planning.