Can an identified environmental correlate of car ownership serve as a practical planning tool?

Previous studies suggest that improving built environment attributes (such as dense development and transit access) has the potential to reduce car ownership. However, most of them overlook the possible plateau association, in which car ownership shows little change as a built environment variable increases within a certain range . Applying gradient boosting decision trees to data from the Minneapolis-St. Paul metropolitan area, this study reveals the complex nonlinear relationships between built environment attributes and car ownership. The results show that although population density and intersection density are strongly and negatively related to car ownership, car ownership exhibits little variation within the middle ranges of these two variables. These plateau associations suggest that reducing car ownership through population and intersection densification is challenging in planning practice. In contrast, directing population growth towards central cities and inner-inning suburbs and densifying transit stops are more promising interventions.