Nonlinear effects of built environment on intermodal transit trips considering spatial heterogeneity

Understanding intermodal transit trip generation is essential to increase the share of long-distance transit trips among urban transportation systems. Although many studies have investigated trip generation, the existing literature still has limited evidence about intermodal transit trips and their nonlinear associations with the built environment over space. This study proposes a decision framework to identify the mean relative importance of socioeconomic attributes and built environment elements as well as their effective ranges and threshold effects at the spatial scale. An empirical study was conducted using large-scale smart card data in Nanjing, China. The modeling results indicate the proposed hybrid model can significantly enhance the predictive power, as compared to traditional models. The mean relative importance of the distance to the nearest metro station ranks the highest among all attributes studied, followed by bus route and land use mix. The effective ranges and thresholds of most built environment elements vary spatially with the upper quartile zones being the largest.