Promoting the integrated use of bikeshare and metro: A focus on the nonlinearity of built environment effects

Bikeshare offers a flexible feeder mode to metro and improves the overall connectivity of urban public transport systems. Although bikeshare has received much research attention, the relationship between the built environment and bikeshare-metro integrated use (i.e. the use of bikeshare for the first/last mile) remains underexplored. Using a one-month dataset of bikeshare trip records in Nanjing, China, this research scrutinizes the built environment correlates of the integrated use. A generalized additive mixed model is employed to capture the temporal autocorrelation attributable to repeated observations over time and the spatial autocorrelation resulting from geographical proximity between individual metro stations. The results show that built environment variables do impose salient nonlinear effects on the bikeshare-metro integrated use. For example, population density only increases the integrated use at certain intervals, and interestingly, extremely high density leads to a decline in bikeshare-metro integrated use. The proportion of commercial and greenspace land uses within metro station catchment areas should not be too high or too low. There exists an optimal land use setting that maximizes the utility of land-use interventions. These findings provide useful policy implications for developing an environment that facilitates the integration of bikeshare and urban metro systems.