Rethinking bus ridership dynamics: Examining nonlinear effects of determinants on bus ridership changes using city-level panel data from 2010 to 2019

The decline of bus ridership is increasingly prevalent in cities in both developed and emerging economies around the world. While researchers have made many efforts to explain why choice riders switch to other transportation modes in single-city cases, why cities vary in the performance of maintaining bus ridership is still largely unknown. This study examines the changes in bus ridership among 175 medium and small-sized cities without urban rail transit from 2010 to 2019 in China and links a few determining factors to such changes by deploying fixed effects panel models and piecewise regression models. Both heterogeneity and nonlinear relationships in the dynamics of bus ridership changes are confirmed. The results demonstrate that cities at different development stages perform diversely in maintaining bus ridership, due to the variations in travel demand and travel choice preferences in those contexts. Increased private car ownership and widening income inequity both contribute to bus ridership decline while an expansion of bus fleet sizes is associated with more bus patronage. These relationships are all displayed as nonlinear formats; the effects can diminish when influencing factors reach a certain level during the growth of cities. The research outcomes may inform policymakers that cities at different development stages need to adopt context-based strategies instead of simply copying from elsewhere. Policies such as controlling private car ownership might not work equally well in cities with diversified characteristics.